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    Wyświetlanie 1-44 z 44
    Tytuł:
    Use of bubble load to interpret particle transport across the pulp-froth interface in a flotation cell
    Autorzy:
    Bhondayi, Clayton
    Powiązania:
    https://bibliotekanauki.pl/articles/1450066.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    bubble loading
    entrainment
    true flotation
    froth flow number
    dropback
    Opis:
    This work demonstrates the use of bubble loads to understand the transport of particles across the pulp-froth interface in a flotation cell processing an Upper Group 2 chromitite seam (UG2) ore. Bubble loads were measured on the first primary cleaner cell of an operating flotation plant using a bubble load meter with a 20mm riser diameter. A bubble load value of 10.58grams/liter was obtained. The bubble load data was used to understand, entrainment and dropback of chromite as a function of particle size. By defining terms such as froth flow number and net dropback, it was found that chromite (known to be non-floatable) was also recovered through true flotation. The entrainment of chromite was found to be predominantly in -25 μm size while +25 μm size particles were found to be floatable and highly susceptible to dropping back. Net-dropback of chromite particles was found to increase with a decrease in chromite particle size contrary to expectation. An overall froth flow number of 69% was obtained.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2020, 56, 1; 54-64
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Odporność na deformacje trwałe betonu asfaltowego przeznaczonego do warstwy ścieralnej z różnymi asfaltami na podstawie badania Flow Number
    The resistance of asphalt concrete for wearing course with various bitumens to permanent deformation based on Flow Number Test
    Autorzy:
    Mejłun, Łukasz
    Jaskuła, Piotr
    Powiązania:
    https://bibliotekanauki.pl/articles/144703.pdf
    Data publikacji:
    2019
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Komunikacji Rzeczpospolitej Polskiej
    Tematy:
    Flow Number
    odporność na deformacje trwałe
    beton asfaltowy
    warstwa ścieralna
    resistance to permanent deformation
    asphalt concrete
    wearing course
    Opis:
    W artykule przedstawiono ocenę odporności na deformacje trwałe betonu asfaltowego AC 11S z asfaltami: drogowym 50/70, modyfikowanym 45/80-55 i wysokomodyfikowanym 45/80-80 na podstawie oceny wyników, mniej znanego w Polsce, badania Flow Number według procedury amerykańskiej. Ocenie poddano następujące parametry: wartość Flow Number (FN), skumulowane odkształcenie trwałe przy liczbie cykli wynoszącej FN i indeks FN. Dodatkowo otrzymane wyniki zostały odniesione do wymagań amerykańskich oraz porównane z wynikami badania odporności mieszanek na koleinowanie wg PN-EN 12697-22.
    In the paper was presented the assessment of resistance to permanent deformation of asphalt concrete for wearing course: AC 11S with bitumens: neat bitumen 50/70, polimer-modified bitumen 45/80-55 and highly-modified bitumen 45/80-80 based on the results assessment of less-known in Poland Flow Number Test according to the American procedure. In the article following parameters were evaluated: the Flow Number (FN) value, the cumulative permanent deformation at the number of cycles of FN and the FN index. Additionally, the obtained results were referred to the American requirements and compared with wheel tracking test results according to PN-EN 12697-22.
    Źródło:
    Drogownictwo; 2019, 7-8; 196-202
    0012-6357
    Pojawia się w:
    Drogownictwo
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    SUPERPAVE design mixture performance evaluation using Epolene modifier for cold semi-arid climatic region of Saudi Arabia
    Autorzy:
    Dahim, M.A.
    Mosaby, M.
    El Morabet, R.
    Khan, R.A.
    Alqadhi, S.
    Khan, N.A.
    Ben Kahla, N.
    Neklonskyi, I.
    Borysova, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/2175741.pdf
    Data publikacji:
    2021
    Wydawca:
    Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
    Tematy:
    SUPERPAVE
    Epolene
    dynamic modulus test
    flow number test
    indirect tensile test
    badanie modułu dynamicznego
    badanie liczby przepływu
    pośrednia próba rozciągania
    Opis:
    Purpose: To evaluate the superpave design performance using Epolene (EE-2) as modifier, since SUPERPAVE design is a modified and sophisticated aspect as compared to previous mix design for asphalt mixtures. This is primarily due to the fact that superpave design mix also takes into consideration properties of materials beside asphalt. Design/methodology/approach: This study was conducted using Epolene (EE-2) as modifier in order to evaluate the performance of SUPERPAVE suitability for construction of roads in Alfaraa campus (King Khalid University) Abha, in Asir Province of Saudi Arabia. Glow number test, dynamic modulus test and indirect tensile strength test were conducted to evaluate the performance of EE-2 modifier against the control mixture. Findings: The mixture modified with EE-2 gave better performance in terms of temperature-based performance and resistance to moisture damage. Also, larger values of E*/sinφ were obtained for EE-2 modified mixture at various loading frequencies and temperature in comparison to control mixture. Research limitations/implications: The Epolene modifier successfully enhances and improves the SUPERPAVE mixture performance. Further studies are required to evaluate the performance of EE-2 modifier at much lower temperature ranges. Practical implications: The results of the study allow us to recommend the investigated asphalt mixture for applied for the construction of roads in the Alfaraa (new campus of King Khalid University), Abha, Asir province, Saudi Arabia. Originality/value: A modified asphalt mixture has been proposed that has better performance at higher and lower temperatures. The developed asphalt mixture is more resistant to moisture damage than the compared to control mixture.
    Źródło:
    Archives of Materials Science and Engineering; 2021, 112, 2; 49--54
    1897-2764
    Pojawia się w:
    Archives of Materials Science and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of Variable Electroconductivity and Radiation on MHD Couette Flow
    Autorzy:
    Ngiangia, Alalibo T.
    Okechukwu, Amadi
    Powiązania:
    https://bibliotekanauki.pl/articles/1192671.pdf
    Data publikacji:
    2016
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    MHD
    Electrconductivity
    Prandtl number
    Grashof number
    Reynolds Number
    Radiation
    Couette flow
    Opis:
    A study of Couette flow in cylindrical coordinate under the influence electroconductivity and magnetic field was carried out. Approximate solution of the governing equations and its analysis show decrease in temperature as a result of increase in radiation and Prandtl number. The study also reveals that increase in grashof number, Reynolds number, Prandtl number and electroconductivity result in an increase in velocity distribution while magnetic field increase, lead to a decrease in velocity. The shear stresses of the outer and inner cylinders at the wall of the plates and the heat flux is also determined.
    Źródło:
    World Scientific News; 2016, 47, 2; 241-253
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Inverse aspects of the three-way catalytic converter operation in the spark ignition engine
    Autorzy:
    Żmudka, Z.
    Postrzednik, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/242021.pdf
    Data publikacji:
    2011
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    catalytic converter
    conversion rate
    flow resistance
    local resistance number
    friction number
    Opis:
    There are two sides of the catalyst operation: favourable and adverse. The positive side can be expressed by a conversion rate of harmful substances which is the principal parameter of catalyst work in respect of ecology. However, resistance of exhaust gas flow through the catalytic converter is also an essential problem. This is just the negative, adverse side of the converter operation. The catalytic converter can be treated as a local or linear resistance element of exhaust system. The first model, in which flow resistance generated by a catalyst is treated as local resistance, is more simplified. It is especially useful in case, when detailed constructional data of converter are unknown and the analysis of flow resistances in exhaust system is necessary. The basic measured quantity of flow resistance is pressure drop of exhaust gas within the catalyst. Next, on the basis of taken measurements also resistance number for the tested catalyst is calculated and analysed. Resistance number of the converter is calculated using Darcy model. In the second case, exhaust gas flow resistance through catalyst is treated as linear resistance with energy dissipation (linear frictional resistance) distributed linearly along way of exhaust gas flow. Friction number for the tested converter is calculated and analysed. The problem has been illustrated by the results of experimental researches of the three-way catalytic converter installed in the exhaust system of the spark ignition engine.
    Źródło:
    Journal of KONES; 2011, 18, 2; 509-516
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical investigation and sensitivity analysis of turbulent heat transfer and pressure drop of Al2O3/H2O nanofluid in straight pipe using response surface methodology
    Autorzy:
    Fadodun, Olatomide G.
    Amosun, Adebimpe A.
    Salau, Ayodeji O.
    Olaloye, David O.
    Ogundeji, Johnson A.
    Ibitoye, Francis I.
    Balogun, Fatai A.
    Powiązania:
    https://bibliotekanauki.pl/articles/239962.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    nusselt number
    Reynolds number
    pressure drop
    response surface methodology
    nanofluid
    single phase flow
    Opis:
    In this paper, investigation of the effect of Reynolds number, nanoparticle volume ratio, nanoparticle diameter and entrance temperature on the convective heat transfer and pressure drop of Al2O3/H2O nanofluid in turbulent flow through a straight pipe was carried out. The study employed a computational fluid dynamic approach using single-phase model and response surface methodology for the design of experiment. The Reynolds average Navier-Stokes equations and energy equation were solved using k-ε turbulent model. The central composite design method was used for the response-surface-methodology. Based on the number of variables and levels, the condition of 30 runs was defined and 30 simulations were performed. New models to evaluate the mean Nusselt number and pressure drop were obtained. Also, the result showed that all the four input variables are statistically significant to the pressure drop while three out of them are significant to the Nusslet number. Furthermore, sensitivity analysis carried out showed that the Reynolds number and volume fraction have a positive sensitivity to both the mean Nusselt number, and pressure drop, while the entrance temperature has negative sensitivities to both.
    Źródło:
    Archives of Thermodynamics; 2020, 41, 1; 3-30
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Soret and Dufour effects on MHD micropolar fluid flow over a linearly stretching sheet, through a non-Darcy porous medium
    Autorzy:
    Reddy, G. V. R.
    Krishna, Y. H.
    Powiązania:
    https://bibliotekanauki.pl/articles/265236.pdf
    Data publikacji:
    2018
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    przepływ magnetohydrodynamiczny
    parametr magnetyczny
    warstwa graniczna
    MHD flow
    magnetic parameter
    Dufour number
    Soret number
    Opis:
    In this paper, we discuss the Soret and Dufour effects on an MHD micropolar fluid flow over a linearly stretching sheet, through a non-Darcy porous medium, where stretching velocity of the sheet varies linearly with distance from the origin, and, temperature and concentration vary non-linearly in the boundary layer region. By suitable similarity transformations, the governing boundary layer equations are transformed to ordinary differential equations. These equations are solved by numerical computations with bvp4c along with the shooting technique method. The effects of the magnetic parameter, Soret number and Dufour number on velocity profiles, microrotation profile, heat transfer, and concentration, skin-friction, Nusselt number and Sherwood number are computed, discussed and analysed numerically and presented through tables and graphs.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2018, 23, 2; 485-502
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The heat transfer and flow structure analyses of low concentration copper nanofluids in a strong magnetic field
    Autorzy:
    Roszko, A.
    Fornalik-Wajs, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/175547.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    nanofluids
    heat transfer
    flow structure
    fast Fourier transform
    Nusselt number ratio
    thermomagnetic Rayleigh number
    Opis:
    Main aim of this paper was to analyze the influence of strong magnetic field on the enhancement or suppression of nanofluids transport processes. The second objective was to determine how the flow structure changed under the influence of a magnetic field. Analyzed diamagnetic nanofluids composed of distilled water and the copper nanoparticles of 40–60 nm size in three different concentrations (50, 500, and 1000 ppm). The experimental enclosure position in the magnet test section caused the most intricate interaction of the acting forces: the gravitational and magnetic buoyancy ones, and made the interpretation of results very difficult. The Nusselt number ratio and the thermomagnetic Rayleigh number were determined for heat transfer analysis, while the fast Fourier transform was performed for the nanofluid flow structure analysis. Spectral analysis for all examined nanofluids was presented. Influence of nanoparticles concentration was clearly visible, while the direct impact of magnetic field on the heat transfer and flow structure should be still investigated.
    Źródło:
    Transactions of the Institute of Fluid-Flow Machinery; 2015, 128; 29-42
    0079-3205
    Pojawia się w:
    Transactions of the Institute of Fluid-Flow Machinery
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A preconditioned solution scheme for the computation of compressible flow in turbomachinery at arbitrary mach numbers
    Autorzy:
    Anker, J. E.
    Mayer, J. F.
    Stetter, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1986683.pdf
    Data publikacji:
    2002
    Wydawca:
    Politechnika Gdańska
    Tematy:
    preconditioning
    non-reflecting boundary condition
    Mach number independency
    turbomachinery flow
    Opis:
    A preconditioned solution scheme for the computation of compressible flow in turbomachinery at arbitrary Mach numbers is presented. The preconditioning technique used is applied to a state-of-the-art explicit, time-marching Navier-Stokes code which originally was developed for compressible, high-speed turbomachinery applications. It combines the ideas of low Mach number preconditioning and artificial compressibility method into a unified approach where principally fluids with arbitrary equations of state can be simulated. As shown by the test cases presented, it allows the code to simulate flows efficiently and accurately independent of the Mach number. A description of the Navier-Stokes equations for rotating coordinate systems, along with the solution scheme and the details of the preconditioning method is given. Since turbomachinery computations are often performed on truncated domains, the solution scheme should be used in conjunction with non-reflecting boundary conditions. A change in the time-dependency of the equations due to preconditioning necessitates a modification of the boundary conditions. Thus, a derivation of the appropriate boundary conditions for the presented preconditioned scheme was performed and the resultant equations are given in this paper. The effectiveness of the new boundary conditions is demonstrated by comparing them with both boundary conditions that use the standard one-dimensional characteristic approach and the original boundary conditions for the non-preconditioned case.
    Źródło:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2002, 6, 1; 143-176
    1428-6394
    Pojawia się w:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Visualization of flow past square cylinders with corner modification
    Autorzy:
    Virkam, C. K.
    Ravindra, H. V.
    Krishnegowda, Y. T.
    Powiązania:
    https://bibliotekanauki.pl/articles/1819175.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Koszalińska. Wydawnictwo Uczelniane
    Tematy:
    flow visualization
    spacing ratio
    Strouhal number
    wizualizacja przepływu
    liczba Strouhala
    Opis:
    This article presents the results for flow past a square cylinder and two square cylinders of same and different size with corner modifications by varying the spacing ratio. Here, experimental work is conducted in a recirculatory channel filled with water. A set of aluminum discs made to rotate to create the flow in the test section. Motor is used to vary the speed of water. Fine aluminum powder is used as a tracer medium. It is observed that vortex shedding frequency decreases by placing second cylinder in the downstream of the first cylinder. For a similar size cylinders, the width of the eddy in the middle of the cylinders increases with increase in spacing ratio. With the increase of spacing ratio to 6, the flow past each cylinder behaves like single square cylinder. If upstream square cylinder size is smaller than the downstream square cylinder, the eddy size is reduced in between the cylinder compared to the downstream of the second cylinder. If upstream square cylinder size is bigger than the downstream square cylinder, the eddy size is larger in between the cylinder compared to the downstream of the second cylinder.
    Źródło:
    Journal of Mechanical and Energy Engineering; 2020, 4, 3; 285--294
    2544-0780
    2544-1671
    Pojawia się w:
    Journal of Mechanical and Energy Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    3D simulation of incompressible flow around a rotating turbulator: Effect of rotational and direction speed
    Autorzy:
    Zoubai, Elhadi
    Laidoudi, Houssem
    Tlanbout, Ismail
    Makinde, Oluwole Daniel
    Powiązania:
    https://bibliotekanauki.pl/articles/27312235.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    rotating
    turbulator
    straight tube
    drag coefficient
    power number
    laminar
    flow
    Opis:
    This paper presents new results for the dynamic behaviour of fluid around a rotating turbulator in a channel. The turbulator has a propeller form which is placed inside a flat channel. The research was carried out using 3D numerical simulation. The rationale of the experiment was as follows: we put a propeller-turbulator inside a flat channel, and then we insert a water flow inside the channel. The turbulator rotates at a constant and uniform speed. The main points studied here are the effect of the presence of turbulator and its rotational direction on the flow behaviour behind the turbulator. The results showed that the behaviour of flow behind the turbulator is mainly related to the direction of turbulator rotating. Also, the studied parameters affect coefficients of drag force and power number. For example, when the turbulator rotates in the positive direction, the drag coefficient decreases in terms of rotational speed of the turbulator, while the drag coefficient increases in terms of rotational speed when the turbulator rotates in the negative direction.
    Źródło:
    Archives of Thermodynamics; 2023, 44, 2; 139--157
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical investigation for convective heat transfer of nanofluid laminar flow inside a circular pipe by applying various models
    Autorzy:
    Saeed, Farqad Rasheed
    Al-Dulaimi, Marwah Abdulkareem
    Powiązania:
    https://bibliotekanauki.pl/articles/1845502.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    convective heat transfer
    Reynolds number
    nanofluid
    single-phase flow
    thermophysical properties
    Opis:
    The work presents a numerical investigation for the convective heat transfer of nanofluids under a laminar flow inside a straight tube. Different models applied to investigate the improvement in convective heat transfer, and Nusselt number in comparison with the experimental data. The impact of temperature dependence, temperature independence, and Brownian motion, was studied through the used models. In addition, temperature distribution and velocity field discussed through the presented models. Various concentrations of nanoparticles are used to explore the results of each equation with more precision. It was shown that achieving the solution through specific models could provide better consistency between obtained results and experimental data than the others.
    Źródło:
    Archives of Thermodynamics; 2021, 42, 1; 71-95
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical investigation and sensitivity analysis of entropy generation of Al2O3/H2O nanofluid in turbulent regime using response surface methodology
    Autorzy:
    Fadodun, Olatomide G.
    Olokuntoye, Bolanle A.
    Salau, Ayodeji O.
    Amosun, Adebimpe A.
    Powiązania:
    https://bibliotekanauki.pl/articles/240104.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    entropy production
    Reynolds number
    response-surface-methodology
    nanofluid
    single-phase flow
    Opis:
    This work investigates the effect of Reynolds number, nanoparticle volume ratio, nanoparticle size and entrance temperature on the rate of entropy generation in Al2O3 /H2O nanofluid flowing through a pipe in the turbulent regime. The Reynolds average Navier-Stokes and energy equations were solved using the standard k-ε turbulent model and the central composite method was used for the design of experiment. Based on the number of variables and levels, the condition of 30 runs was defined and 30 simulations were run. The result of the regression model obtained showed that all the input variables and some interaction between the variables are statistically significant to the entropy production. Furthermore, the sensitivity analysis result shows that the Reynolds number, the nanoparticle volume ratio and the entrance temperature have negative sensitivity while the nanoparticle size has positive sensitivity.
    Źródło:
    Archives of Thermodynamics; 2020, 41, 2; 119-146
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Heat transfer study from square cylinder immersed in water-based nanofluid: Effect of orientation
    Autorzy:
    Kaur, Jaspinder
    Ratar, Jatinder Kumar
    Tiwari, Anurag Kumar
    Powiązania:
    https://bibliotekanauki.pl/articles/2173435.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    inclined square cylinder
    nanofluids
    Reynolds number
    Prandtl number
    steady flow
    regime
    nanopłyn
    liczba Reynoldsa
    liczba Prandtla
    przepływ stały
    Opis:
    Heat transfer study from the heated square cylinder at a different orientation angle to the stream of nanofluids has been investigated numerically. CuO-based nanofluids were used to elucidate the significant effect of parameters: Reynolds number (1–40), nanoparticle volume fraction (0.00–0.05), the diameter of the NPs (30–100 mn) and the orientation of square cylinder (0–90). The numerical results were expressed in terms of isotherm contours and average Nusselt number to explain the effect of relevant parameters. Over the range of conditions, the separation of the boundary layers of nanofluids increased with the size of the NPs as compared to pure water. NPs volume fraction and its size had a significant effect on heat transfer rate. The square cylinder of orientation angle (45) gained a more efficient heat transfer cylinder than other orientation angles. Finally, the correlations were developed for the average Nusselt number in terms of the relevant parameters for 45 orientation of the cylinder for new applications.
    Źródło:
    Chemical and Process Engineering; 2022, 43, 2; 243--250
    0208-6425
    2300-1925
    Pojawia się w:
    Chemical and Process Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical investigation on the transition of fluid flow characteristics through a rotating curved duct
    Autorzy:
    Hasan, Mohammad Sanjeed
    Islam, MD. Sirajul
    Badsha, MD. Faisal
    Mondal, Rabindra Nath
    Lorenzini, Giulio
    Powiązania:
    https://bibliotekanauki.pl/articles/1839803.pdf
    Data publikacji:
    2020
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    wymiana ciepła
    przepływ wtórny
    liczba Taylora
    rotating curved duct
    Taylor number
    flow transition
    secondary flow
    heat transfer
    Opis:
    Time-dependent flow investigation through rotating curved ducts is utilized immensely in rotating machinery and metal industry. In the ongoing exploration, time-dependent solutions with flow transition through a rotating curved square duct of curvature ratio 0.009 have been performed. Numerical calculations are carried out for constant pressure gradient force, the Dean number Dn = 1000 and the Grashof number Gr = 100 over a wide range of the Taylor number values […] for both positive and negative rotation of the duct. The software Code:Blocks has been employed as the second programming tool to obtain numerical solutions. First, time evolution calculations of the unsteady solutions have been performed for positive rotation. To clearly understand the characteristics of regular and irregular oscillations, phase spaces of the time evolution results have been enumerated. Then the calculations have been further attempted for negative rotation and it is found that the unsteady flow shows different flow instabilities if Tr is increased or decreased in the positive or in the negative direction. Two types of flow velocities such as axial flow and secondary flow and temperature profiles have been exposed, and it is found that there appear two- to four-vortex asymmetric solutions for the oscillating flows for both positive and negative rotation whereas only two-vortex for the steady-state solution for positive rotation but four-vortex for negative rotation. From the axial flow pattern, it is observed that two high-velocity regions have been created for the oscillating flows. As a consequence of the change of flow velocity with respect to time, the fluid flow is mixed up in a great deal which enhances heat transfer in the fluid.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2020, 25, 3; 45-63
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Pomiar kryzą segmentową strumienia medium dla małych liczb Reynoldsa
    Measurement with segmental orifice of flow medium for small Reynolds numbers
    Autorzy:
    Mrowiec, A.
    Kasprzak, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/267014.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Gdańska. Wydział Elektrotechniki i Automatyki
    Tematy:
    kryza segmentowa
    liczba Reynoldsa
    współczynnik przepływu
    segmental orifice
    Reynolds number
    flow factor
    Opis:
    Podstawowym surowcem energetycznym w Polsce jest węgiel. W ostatnich latach podejmowano próby spalania koloidalnych zawiesin pyłu węglowego w oleju napędowym lub opałowym. Przy pomiarach przepływu takich zawiesin, może dochodzić do wytrącania i zalegania w układach przesyłowych osadów, co w efekcie może prowadzić do zaburzeń strumienia przepływu. Wiarygodność pomiaru tego parametru, mogą zapewnić kryzy segmentowe. W artykule zaprezentowano wyniki badań przepływowych kryz segmentowych z przytarczowym punktowym odbiorem ciśnienia różnicowego, przy niewielkich liczbach Reynoldsa oraz symulacje numeryczne dla wybranej kryzy. W badaniach jako medium wykorzystano wodę.
    In Poland coal is the main energy resource. As part of the conducted research attempts were made at using suspensoids containing coal dust in gas oil and furnace oil. This leads to a reduction in NOx and SOx percentage without the need for an expensive desulphurization and dust extraction installation. However, there is a need for using cheap but reliable systems to measure the flow of the injected fuel. In real operating conditions various residues may often deposit in fuel transmission systems, which in turn can lead to flow fluctuations. Reliable flow factor measurement requirements can be met by segmental orifices. In the article, based on a research and measurement station, presented were the results of flow measurements with segmental orifices with point reception of differential pressure for small Reynolds numbers as well as numerical simulations. For the selected segmental orifice the flow factor characteristic in the function of the Reynolds number was calculated. In the research, water was used as the medium; the next stage of the research will involve the realization of the proposed solution with the use of hydraulic oil.
    Źródło:
    Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej; 2016, 49; 75-78
    1425-5766
    2353-1290
    Pojawia się w:
    Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Design and validation of a single-jack variable Mach number nozzle in a cryogenic transonic wind tunnel
    Autorzy:
    Yu, Chengguo
    Zhang, Zhili
    Wang, Ning
    Nie, Xutao
    Peng, Qiang
    Chen, Zhenhua
    Powiązania:
    https://bibliotekanauki.pl/articles/2200829.pdf
    Data publikacji:
    2022
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    cryogenic
    flow uniformity
    single-jack nozzle
    transonic wind tunnel
    variable
    Mach number
    Opis:
    The wind tunnel with variable Mach numbers controlled by a single jack is highly desired in the aerospace, automobile and building industry due to its superior controllability and working range. Decreasing the temperature of a test gas is an efficient and economical approach to achieving higher Reynolds numbers that accommodate all working statuses of test subjects, which however, brings new challenges to the wind tunnel design nowadays. This paper proposes a new design concept of a single-jack variable Mach number nozzle based on its particular cryogenic characteristics, as the nozzle is the core structure to achieve variable Mach numbers. The contours of the nozzle under different Reynolds numbers and Mach numbers are modeled and solved by an incomplete elliptic integral, followed by modification with cryogenic characteristics. A 0.3-m cryogenic wind tunnel is utilized as a validation platform for the nozzle design, resulting in designed contours being in line with the measured contours. Moreover, the root means square (RMS) deviations of Mach number 1.3 at the core position are controlled within 0.011 in low and high temperatures, which surpasses the other existing wind tunnels.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2022, 60, 4; 719--732
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis of selected aspects of a tank gassing-up process on board liquefied petroleum gas carrier. Part I
    Autorzy:
    Wieczorek, Agnieszka
    Powiązania:
    https://bibliotekanauki.pl/articles/1845464.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    convective heat transfer
    Reynolds number
    nanofluid
    single
    wall
    carbon
    nanotube
    SWCNT
    laminar flow
    Opis:
    The paper is a thermodynamics analysis of the removal of any inert gas from the tank using the vapors of any liquefied petroleum gas cargo (called cargo tank gassing-up operation). For this purpose, a thermodynamic model was created which considers two boundary cases of this process. The first is a ‘piston pushing’ of inert gas using liquefied petroleum gas vapour. The second case is complete mixing of both gases and removal the mixture from the tank to the atmosphere until desired concentration or amount of liquefied petroleum gas cargo in the tank is reached. Calculations make it possible to determine the amount of a gas used to complete the operation and its loss incurred as a result of total mixing of both gases.
    Źródło:
    Archives of Thermodynamics; 2021, 42, 2; 43-58
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical investigation of convective heat transfer of single wall carbon nanotube nanofluid laminar flow inside a circular tube
    Autorzy:
    Saeed, Farqad Rasheed
    Jasim, Marwah A.
    Mahmood, Natheer B.
    Jaffar, Zahraa M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1845470.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    convective heat transfer
    reynolds number
    nanofluid
    single
    wall
    carbon
    nanotube
    SWCNT
    laminar flow
    Opis:
    This study presents the behavior of a single wall carbon nanotube (SWCNT)/water nanofluid for convective laminar flow inside a straight circular pipe heated by a constant heat flux. Five volume fractions of SWCNT were used to investigate their effect on the heat transfer coefficient, Nusselt number, temperature distribution and velocity field in comparison with pure water flow. One model for each property was tested to calculate the effective thermal conductivity, effective dynamic viscosity, and effective specific heat of the SWCNT/water mixture. The models were extracted from experimental data of a previous work. The outcomes indicate that the rheological behavior of SWCNT introduces a special effect on the SWCNT/water properties, which vary with SWCNT volume fraction. The results show an improvement in the heat transfer coefficient with increasing volume fraction of nanoparticles. The velocity of SWCNT/water nanofluid increased by adding SWCNT nanoparticles, and the maximum increase was registered at 0.05% SWCNT volume fraction. The mixture temperature is increased with the axial distance of the pipe but a reduction in temperature distribution is observed with the increasing SWCNT volume fraction, which reflects the effect of thermophysical properties of the mixture.
    Źródło:
    Archives of Thermodynamics; 2021, 42, 2; 103-119
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A Numerical Study of Combined Natural and Marangoni Convection in a Square Cavity
    Autorzy:
    Cicek, K.
    Baytas, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/116928.pdf
    Data publikacji:
    2009
    Wydawca:
    Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
    Tematy:
    Numerical Study
    Square Cavity
    natural convection
    Marangoni Convection
    Buoyancy-Driven Flow
    Thermo Capillary Flow
    Navier-Stokes Equations
    Rayleigh Number
    Opis:
    Through the aim of this study, the effects of combined buoyancy-driven flows and thermo capillary flows, which are emerged from temperature differences, on fluid flow and heat transfer numerically investigated with differentially heated side walls in a free surface square cavity. The study has been accomplished with three milestones to achieve the right solutions. For every milestone Navier-Stokes, continuity and energy equations are discretized by using finite volume method and grids with 52 x 52 control volumes. Results are presented Pr=1, Pr=7 and Pr=100. The effect of positive and negative Marangoni number on fluid flow and heat transfer at different Rayleigh number are considered and discussed.
    Źródło:
    TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2009, 3, 2; 173-178
    2083-6473
    2083-6481
    Pojawia się w:
    TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Catalytic reactor as a resistance element of ICE exhaust system
    Autorzy:
    Postrzednik, S.
    Żmudka, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/242786.pdf
    Data publikacji:
    2007
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    internal combustion engine
    catalytic converter
    pressure drop
    local and linear flow resistance
    resistance number
    Opis:
    Selected problems connected with operation of catalytic reactors are presented. Conversion rate of harmful substances is the principal parameter of catalyst work in respect of ecology. However, resistance of exhaust gas flow through the catalytic converter is also essential problem, apart from its chemical efficiency because fitting the catalyst in exhaust system alters flow characteristic of this system significantly. Catalytic converter can be treated as local or linear resistance element of exhaust system. The first model, in which flow resistance generated by a catalyst is treated as local resistance, is more simplified. Resistance number of the converter was calculated using Darcy model. In the second case, exhaust gas flow resistance through catalyst is treated as linear resistance with energy dissipation (linear frictional resistance) distributed linearly along way of exhaust gas flow. Friction number for the tested converter was calculated and analysed. The problem has been illustrated by results of experimental researches of three-way catalytic converter installed in exhaust system of spark ignition engine and its basic analysis.
    Źródło:
    Journal of KONES; 2007, 14, 4; 351-356
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Heat transfer and friction characteristics in three-side solar air heaters with the combination of multi-v and transverse wire roughness
    Autorzy:
    Kumar, Dhananjay
    Powiązania:
    https://bibliotekanauki.pl/articles/2204071.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    absorber plate
    fluid flow
    heat transfer
    solar air heater
    reynolds number
    relative roughness height
    Opis:
    The present paper describes the experimental analysis of heat transfer and friction factor for glass protected three-side artificially roughened rectangular duct solar air heaters (SAHs) having an arrangement of multiple-v and transverse wires (top wall multi-v and two side walls transverse) under the absorber plate, and compares their performance with that of one-side roughened solar air heaters under similar operating conditions. The investigated three-side solar air heaters are characterized by a larger rate of heat transfer and friction factor as compared to one-side artificially roughened SAHs by 24–76% and 4–36%, respectively, for the identical operating parameters. The air temperature below the three-side rugged duct is by 34.6% higher than that of the one-side roughened duct. Three-side solar air heaters are superior as compared to one-side artificially roughened solar air heaters qualitatively and quantitatively both.
    Źródło:
    Archives of Thermodynamics; 2023, 44, 1; 63--87
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Transient velocity and steady state entropy generation in a microfluidic Couette flow containing charged nano particles
    Autorzy:
    Gorla, R. S. R.
    Gireesha, B. J.
    Powiązania:
    https://bibliotekanauki.pl/articles/264851.pdf
    Data publikacji:
    2015
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    transient velocity
    steady state entropy generation
    microfluidic Couette flow
    charged nanoparticles
    Bejan number and Brinkman number
    przepływ Couette'a
    liczba Brinkmana
    nanocząsteczki
    Opis:
    An analysis has been provided to determine the transient velocity and steady state entropy generation in a microfluidic Couette flow influenced by electro-kinetic effect of charged nanoparticles. The equation for calculating the Couette flow velocity profile is derived for transient flow. The solutions for momentum and energy equations are used to get the exact solution for the dimensionless velocity ratio and dimensionless entropy generation number. The effects of the dimensionless entropy generation number, Bejan number, irreversibility ratio, entropy generation due to fluid friction and due to heat transfer on dimensionless time, relative channel height, Brinkman number, dimensionless temperature ratio, nanoparticle volume fraction are analyzed.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2015, 20, 4; 787-804
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Review of Methods and Algorithms for Modelling Transportation Networks Based on Graph Theory
    Przegląd metod i algorytmów modelowania sieci transportowych opartych na teorii grafów
    Autorzy:
    Guze, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/341823.pdf
    Data publikacji:
    2018
    Wydawca:
    Uniwersytet Morski w Gdyni. Wydawnictwo Uniwersytetu Morskiego w Gdyni
    Tematy:
    knapsack problem
    domination number
    bondage-connected number
    MST
    maximal flow
    transportation network
    vulnerability
    problem plecakowy
    liczba dominowania
    liczba zniewolenia spójnego
    maksymalny przepływ
    sieć transportowa
    wrażliwość sieci
    Opis:
    One of the best ways of modelling a transport network is to use a graph with vertices and edges. They represent nodes and arcs of such network respectively. Graph theory gives dozens of parameters or characteristics, including a connectivity, spanning trees or the different types of domination number and problems related to it. The main aim of the paper is to show graph theory methods and algorithms helpful in modelling and optimization of a transportation network. Firstly, the descriptions of basic notations in graph theory are introduced. Next, the concepts of domination, bondage number, edge-subdivision and their implementations to the transportation network description and modeling are proposed. Moreover, the algorithms for finding spanning tree or maximal flow in networks are presented. Finally, the possible usage of distinguishing concepts to exemplary transportation network is shown. The conclusions and future directions of work are presented at the end of the paper.
    Jednym z najlepszych sposobów modelowania sieci transportowej jest użycie grafu z wierzchołkami i krawędziami. Reprezentują one odpowiednio węzły i łuki takiej sieci. Teoria grafów daje możliwość użycia dziesiątek parametrów lub charakterystyk, w tym spójności, drzew spinających lub różnych typów liczb dominowania i związanych z tym problemów. Głównym celem artykułu jest przedstawienie metod i algorytmów teorii grafów pomocnych w modelowaniu i optymalizacji sieci transportowej. Po pierwsze, wprowadzono opisy podstawowych pojęć w teorii grafów. Następnie zaprezentowano koncepcje dominowania, liczby zniewolenia czy podziału krawędzi grafu oraz ich implementacji do opisu i modelowania sieci transportowej. Ponadto przedstawiono algorytmy do wyszukiwania drzewa opinającego i maksymalnego przepływu w sieciach. Wreszcie pokazano możliwe sposoby wykorzystania wyróżnionych koncepcji do przykładu sieci transportowej. Na zakończenia przedstawiono wnioski i przyszłe kierunki prac.
    Źródło:
    Zeszyty Naukowe Akademii Morskiej w Gdyni; 2018, 107; 25-39
    1644-1818
    2451-2486
    Pojawia się w:
    Zeszyty Naukowe Akademii Morskiej w Gdyni
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Sprawdzenie możliwości pomiaru kryzą mimośrodową strumienia medium dla małych liczb Reynoldsa
    Analysis of the Possibilities of Measurement with Eccentric Orifice of Flow Medium for Small Reynolds Numbers
    Autorzy:
    Kasprzak, D.
    Mrowiec, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/275070.pdf
    Data publikacji:
    2016
    Wydawca:
    Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów
    Tematy:
    kryza mimośrodowa
    liczba Reynoldsa
    współczynnik przepływu
    przetwornik różnicy ciśnienia
    eccentric orifice
    Reynolds number
    flow factor
    differential pressure sensor
    Opis:
    Węgiel to podstawowy surowiec energetyczny w Polsce. Od połowy ubiegłego wieku podejmowano próby spalania koloidalnych zawiesin pyłu węglowego w oleju napędowym lub opałowym. Ze względów ekonomicznych podjęto badania nad wykorzystaniem koloidalnych zawiesin wodno-węglowych CWL (Coal-Water Liquid), jako paliwa w energetyce ciepłowniczej. Pozwala to na obniżenie zawartości NOx i SOx bez konieczności inwestowania w drogie układy odsiarczania i odpylania, co jest atutem ekologicznym i ekonomicznym. Wymagane, ze względów technologicznych, układy pomiaru strumienia dostarczanego paliwa, powinny być tanie w eksploatacji, niezawodne oraz odporne na zanieczyszczenia. Warunki te mogą spełnić kryzy mimośrodowe lub segmentowe. W artykule przedstawiono stanowisko doświadczalno-pomiarowe, pozwalające na przeprowadzenie przepływowych badań wstępnych, kryz mimośrodowych z punktowym odbiorem ciśnienia różnicowego, przy małych liczbach Reynoldsa. Wyniki wykonanych pomiarów charakterystyk przepływowych oraz symulacji numerycznych przedstawiono w tabelach i na wykresach. Dla wybranej kryzy mimośrodowej wyznaczono wartość współczynnika przepływu C w funkcji liczby Reynoldsa. Przedstawione w artykule analizy dotyczą przepływu wody. Planowane są dalsze badania dla oleju hydraulicznego.
    The energy industry in Poland is mostly based on coal as an energy resource. Until the half of the previous century studies and attempts were made at burning coal dust-based suspensoids in gas oil and furnace oil, with positive results. For economic reasons, studies and attempts were made at using coal and water-based CWL (Coal-Water Liquid) suspensoids as fuel in the heating industry. Using this fuel leads to a reduction in NOx and SOx percentage without the need for an expensive desulphurization and dust extraction installation, which is a huge economic and ecological advantage. For technological reasons required are systems for measuring the flow of the injected fuel that are cheap in use, reliable and residue-resistant. These requirements can be met by segmental and eccentric orifices. In the article, presented was a research and measurement station which enables its users to conduct introductory flow measurements for eccentric orifices with point reception of differential pressure for small Reynolds numbers. The results of the flow characteristic measurements as well as of numerical simulations were presented in the form of tables and charts. For the selected eccentric orifice the C flow parameter in the Reynolds number function was determined. The analysis of the study results presented in the article refers to the flow of water. The next planned stage of the research will involve flow studies and measurements with the use of hydraulic oil as the medium.
    Źródło:
    Pomiary Automatyka Robotyka; 2016, 20, 2; 25-28
    1427-9126
    Pojawia się w:
    Pomiary Automatyka Robotyka
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Development of a source code to analyze the effect of Reynolds number on a square lid driven cavity
    Autorzy:
    Rahi, K. H.
    Mortuza, G. M.
    Al-Faruk, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/95291.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Koszalińska. Wydawnictwo Uczelniane
    Tematy:
    lid driven cavity
    Reynolds number
    artificial compressibility method
    fluid flow characteristics
    liczba Reynoldsa
    metoda sztucznej ściśliwości
    charakterystyka przepływowa
    Opis:
    Numerical simulations of two-dimensional, steady, incompressible lid driven flow in a square cavity were investigated in this work. A commercial finite volume package of ANSYS-FLUENT was used to analyze and visualize the nature of the flow inside the cavity at different Reynolds Numbers. In addition, a MATLAB code was developed and validated by comparing the results with the reference values from literature. Staggered grid was employed in the discretization of the cavity to avoid checkerboard pressure while developing the code. The governing equations were discretized in terms of velocity and pressure fields. The artificial compressibility method was used to de-couple the pressure and velocity terms in the governing equations. A 129×129 grid system was used in both cases. The effects of Reynolds number (100≤ Re ≤ 1000) on the flow characteristics were illustrated through an analysis of stream function, velocity vector, pressure co-efficient and velocity contours. The thinning of the wall boundary layers with an increase in the Reynolds number is evident from the u and v velocity profiles along the vertical and horizontal lines at the geometric center, although the rate of this thinning is very slow for Re> 5000.
    Źródło:
    Journal of Mechanical and Energy Engineering; 2018, 2, 2; 147-154
    2544-0780
    2544-1671
    Pojawia się w:
    Journal of Mechanical and Energy Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Transport of MHD couple stress fluid through peristalsis in a porous medium under the influence of heat transfer and slip effects
    Autorzy:
    Sankad, G. C.
    Nagathan, P. S.
    Powiązania:
    https://bibliotekanauki.pl/articles/266102.pdf
    Data publikacji:
    2017
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    peristaltic flow
    couple stress fluid
    Darcy number
    slip parameter
    compliant walls
    przepływ perystaltyczny
    liczba Darcy'ego
    parametr poślizgu
    Opis:
    An attempt has been made to examine the effects of magnetohydrodynamic couple stress fluid in peristaltic flow with porous medium under the impact of slip, heat transfer and wall properties. The expressions are obtained for temperature, coefficient of heat transfer and velocity. Influences of different parameters, the Hartmann number, Brinkman number and adaptability parameters on the temperature and warmth trade coefficient are discussed through outlines.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2017, 22, 2; 403-414
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Enhancement of turbulent airflow and heat transfer through a rectangular microchannel with different types of baffles
    Autorzy:
    Saha, Sandip
    Raut, Santanu
    Das, Apurba Narayan
    Powiązania:
    https://bibliotekanauki.pl/articles/2141504.pdf
    Data publikacji:
    2021
    Wydawca:
    Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
    Tematy:
    turbulent air flow
    heat transfer
    local Nusselt number
    friction coefficient
    turbulentny przepływ powietrza
    wymiana ciepła
    liczba Nusselta
    współczynnik tarcia
    Opis:
    The objective of this work is to discuss the turbulent air hydro-thermal phenomena over a rectangular microchannel with different types of baffle (rectangular, triangular, and trapezoidal) mounted on both the walls of the microchannel. The finite volume method with the second order upwind scheme has been utilized to discretize the governing equations and to study the turbulent airflow characteristics; the SST k-ꞷ turbulence model has been adopted. For nine different cases, the different characteristics of fluid flow phenomena and thermal behaviour with the variations in the Reynolds number ranging from [5,000-25,000] and for three different values of inter baffle spacing have been studied in this manuscript. Due to the presence of baffle, it is revealed that the vortex arises on the upper wall and the thermal phenomena enhances with the decrease in inter baffle spacing.
    Źródło:
    Journal of Applied Mathematics and Computational Mechanics; 2021, 20, 3; 41-52
    2299-9965
    Pojawia się w:
    Journal of Applied Mathematics and Computational Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical computation of low Reynolds number viscous flow past bluff bodies
    Autorzy:
    Tarafder, Md. Shahjada
    Mursaline, Miad Al
    Powiązania:
    https://bibliotekanauki.pl/articles/1839825.pdf
    Data publikacji:
    2020
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    przepływ
    płyn lepki
    liczba Reynoldsa
    współczynnik oporu
    viscous flow
    low Reynolds number
    SIMPLE algorithm
    circular cylinder
    square cylinder
    drag coefficient
    Opis:
    This article presents a two-dimensional steady viscous flow simulation past circular and square cylinders at low Reynolds numbers (based on the diameter) by the finite volume method with a non-orthogonal body-fitted grid. Diffusive fluxes are discretized using central differencing scheme, and for convective fluxes upwind and central differencing schemes are blended using a ‘deferred correction’ approach. A simplified pressure correction equation is derived, and proper under-relaxation factors are used so that computational cost is reduced without adversely affecting the convergence rate. The governing equations are expressed in Cartesian velocity components and solution is carried out using the SIMPLE algorithm for collocated arrangement of variables. The mesh yielding grid-independent solution is then utilized to study, for the very first time, the effect of the Reynolds number on the separation bubble length, separation angle, and drag coefficients for both circular and square cylinders. Finally, functional relationships between the computed quantities and Reynolds number (Re) are proposed up to Re = 40. It is found that circular cylinder separation commences between Re= 6.5-6.6, and the bubble length, separation angle, total drag vary as Re, Re-0.5, Re-0.5 respectively. Extrapolated results obtained from the empirical relations for the circular cylinder show an excellent agreement with established data from the literature. For a square cylinder, the bubble length and total drag are found to vary as Re and Re-0.666, and are greater than these for a circular cylinder at a given Reynolds number. The numerical results substantiate that a square shaped cylinder is more bluff than a circular one.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2020, 25, 3; 133-157
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Convective heat transfer in a micropolar fluid over an unsteady stretching surface
    Autorzy:
    Prasad, K. V.
    Vaidya, H.
    Vajravelu, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/266164.pdf
    Data publikacji:
    2016
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    przepływ niestacjonarny
    wymiana ciepła
    tarcie
    metoda Keller-box
    unsteady flow
    microrotation
    heat transfer
    skin friction
    Nusselt number
    Keller-box method
    Opis:
    An unsteady boundary layer free convective flow and heat transfer of a viscous incompressible, microploar fluid over a vertical stretching sheet is investigated. The stretching velocity is assumed to vary linearly with the distance along the sheet. Two equal and opposite forces are impulsively applied along the x-axis so that the sheet is stretched, keeping the origin fixed in the micropolar fluid. The transformed highly non-linear boundary layer equations are solved numerically by an implicit finite difference scheme for the transient, state from the initial to the final steady-state. To validate the numerical method, comparisons are made with the available results in the literature for some special cases and the results are found to be in good agreement. The obtained numerical results are analyzed graphically for the velocity, the microrotation, and the temperature distribution; whereas the skin friction, the couple stress coefficient and the Nusselt number are tabulated for different values of the pertinent parameters. Results exhibit a drag reduction and an increase in the surface heat transfer rate in the micropolar fluid flow compared to the Newtonian fluid flow.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2016, 21, 2; 407-422
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Zależność współczynnika strat miejscowych od liczby Reynoldsa podczas przepływu wody przez nagłe zwężenie rury
    Dependence of the resistance coefficient on the Reynolds number during flow through pipe sudden constriction
    Autorzy:
    Wędrychowicz, W.
    Jeżowiecka-Kabsch, K.
    Grygoriev, A.
    Strzelecka, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/236396.pdf
    Data publikacji:
    2006
    Wydawca:
    Polskie Zrzeszenie Inżynierów i Techników Sanitarnych
    Tematy:
    współczynnik strat miejscowych
    przepływ
    ciecz lepka
    liczba Reynoldsa
    nagłe zwężenie rury
    resistance coefficient
    viscous flow
    pipe sudden constriction
    Reynolds number
    Opis:
    Projektowanie układów hydraulicznych w głównej mierze opiera się na znajomości współczynnika strat miejscowych (?) na elementach stanowiących układ przepływowy. Wartości tego współczynnika, wyznaczone najczęściej na drodze doświadczalnej, podawane są w postaci stabelaryzowanej. W tabelach tych, w odniesieniu do oporu miejscowego w postaci nagłego zwężenia rury, podawana jest jedna wartość współczynnika dotycząca zadanego stopnia zwężenia, zatem zakłada się jego niezależność od liczby Reynoldsa. W pracy przeanalizowano wpływ liczby Reynoldsa (Red (10000;120000)) i stopnia zwężenia (D/d (1,58;2,87)) na wartość doświadczalnie wyznaczonego współczynnika strat miejscowych. Określono strefy przepływów, w których wartości współczynnika ? zależą od Red, sporządzono krzywą graniczną oddzielającą strefy zależności ? od Red, porównano wyniki uzyskane doświadczalnie i obliczone ze wzoru podawanego literaturze. Stwierdzono, że wartość współczynnika strat miejscowych zależy od liczby Reynoldsa w zakresie Red
    Hydraulic system design requires the knowledge of the resistance coefficients for the elements being part of the flow system. In specialized literature, the values of the resistance coefficients (generally determined by experiments) are presented in tabular form. In those tables, only one resistance coefficient value is given for the diameter ratio chosen, and hence the assumption that the value is constant over the entire range of the Reynolds number. In the study reported on in this paper, consideration was given to the effect of the Reynolds number Red (10000;120000) and the diameter ratio D/d (1.58;2.87) on the experimental values of the resistance coefficient. Flow zones where the resistance coefficient values ? depended on the Reynolds number Re were determined and the relevant limiting curve was plotted. The comparison of experimental and theoretical results has shown that the resistance coefficient values depend on the Reynolds number in the range of Red
    Źródło:
    Ochrona Środowiska; 2006, R. 28, nr 3, 3; 51-54
    1230-6169
    Pojawia się w:
    Ochrona Środowiska
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Symulacja konwekcji wymuszonej w przewodach prostoosiowych przy przepływie laminarnym metodą elementów brzegowych
    Boundary elements method simulation of laminar flow forced convection in duct
    Autorzy:
    Teleszewski, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/371849.pdf
    Data publikacji:
    2014
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    konwekcja wymuszona
    przewody prostoosiowe
    liczba Nusselta
    metoda elementów brzegowych (MEB)
    forced convection
    flow in ducts
    Nusselt number
    boundary element method (BEM)
    Opis:
    W pracy przedstawiono algorytm symulacji konwekcji wymuszonej MEB przy przepływie laminarnym w przewodach prostoosiowych niezależnie od kształtu poprzecznego przewodu. Weryfikacja algorytmu została wykonana poprzez porównanie rezultatów MEB z rozwiązaniem analitycznym. W publikacji wyznaczono zależność liczby Nusselta od liczby boków w przewodach o przekroju wielokąta foremnego.
    The paper presents the numerical algorithm Boundary Element Method to simulation modelling forced convection in a duct. The efficiency and the credibility of proposed algorithm were verified by numerical tests in theoretical solution. A numerical examples are presented fully developed forced convection through pentagon duct. In this study is proposed for determining the Nusselt number in regular polygonal channels.
    Źródło:
    Zeszyty Naukowe. Inżynieria Środowiska / Uniwersytet Zielonogórski; 2014, 153 (33); 117-127
    1895-7323
    Pojawia się w:
    Zeszyty Naukowe. Inżynieria Środowiska / Uniwersytet Zielonogórski
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Unsteady hydromagnetic Couette flow due to ramped motion of one of the porous plates
    Autorzy:
    Jha, B. K.
    Jibril, H. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/955270.pdf
    Data publikacji:
    2013
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    przepływ Couette'a
    pole magnetyczne poprzeczne
    magnetohydrodynamika
    Couette flow
    transverse magnetic field
    suction/injection
    MHD
    ramp motion
    Hartmann number
    porous plates
    Opis:
    An unsteady flow formation in Couette motion of an electrically conducting fluid subject to transverse magnetic field has been analyzed in the presence of suction/injection through the porous plates when one of the porous plates is in ramped motion. It is assumed that the porous plates are uniformly permeable and the fluid is entering the flow region through one of the porous plates at same rate as it is leaving through the other porous plate. The resulting boundary value problem has been solved exactly under the assumption of a negligible induced magnetic field, external electric field and pressure gradient. Unified closed form expressions for the velocity field and skin-friction corresponding to the case of a magnetic field fixed relative to the fluid or to the moving porous plate have been presented. In order to highlight the impact of the ramp motion of the porous plate on the fluid flow, it has also been compared with Couette flow between porous plates when one of the porous plates has been set into an impulsive motion.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2013, 18, 4; 1039-1056
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical and analytical calculations of the free surface flow between two semi-infinite straights
    Autorzy:
    Chedala, Fatma Zohra
    Amara, Abdelkader
    Meflah, Mabrouk
    Powiązania:
    https://bibliotekanauki.pl/articles/1839736.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
    Tematy:
    free surface
    flow
    surface tension
    free streamline theory
    exact solution
    series truncation
    Weber number
    numer Webera
    napięcie powierzchniowe
    dokładne rozwiązanie
    przepływ swobodny
    Opis:
    The problem of two-dimensional flow with the free surface of the jet in a region between two semi-infinite straights intersections at point O is calculated analytically for each angle Beta and numerically for each of the various values of the Weber number and angle Beta. By assuming that the flow is potential, irrotational and that the fluid is incompressible and inviscid, and by taking account only the surface tension for a numerical method using the series truncation, and without the effect of gravity and surface tension for the analytic method utilize the hodograph transformation. The obtained results confirmed a good agreement between them when the Weber number tends to infinity, and the comparison of these surface shapes is illustrated.
    Źródło:
    Journal of Applied Mathematics and Computational Mechanics; 2020, 19, 4; 21-32
    2299-9965
    Pojawia się w:
    Journal of Applied Mathematics and Computational Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical and analytical calculations of the free surface flow between two semi-infinite straights
    Autorzy:
    Chedala, Fatma Zohra
    Amara, Abdelkader
    Meflah, Mabrouk
    Powiązania:
    https://bibliotekanauki.pl/articles/1839739.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
    Tematy:
    free surface
    flow
    surface tension
    free streamline theory
    exact solution
    series truncation
    Weber number
    numer Webera
    napięcie powierzchniowe
    dokładne rozwiązanie
    przepływ swobodny
    Opis:
    The problem of two-dimensional flow with the free surface of the jet in a region between two semi-infinite straights intersections at point O is calculated analytically for each angle Beta and numerically for each of the various values of the Weber number and angle Beta. By assuming that the flow is potential, irrotational and that the fluid is incompressible and inviscid, and by taking account only the surface tension for a numerical method using the series truncation, and without the effect of gravity and surface tension for the analytic method utilize the hodograph transformation. The obtained results confirmed a good agreement between them when the Weber number tends to infinity, and the comparison of these surface shapes is illustrated.
    Źródło:
    Journal of Applied Mathematics and Computational Mechanics; 2020, 19, 4; 21-32
    2299-9965
    Pojawia się w:
    Journal of Applied Mathematics and Computational Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Setting up of automatic train and wagon number recording (reading), control and tracking devices at sectional and sorting stations, Latvia
    Autorzy:
    Mezitis, M.
    Pinchuk, A.
    Dadoenkov, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/315014.pdf
    Data publikacji:
    2017
    Wydawca:
    Instytut Naukowo-Wydawniczy "SPATIUM"
    Tematy:
    RFID
    Radio Frequency Identification
    Latvia
    railroad transport
    cargo flow
    automatic train number recording
    automatic wagon number recording
    automatic registration
    identyfikacja radiowa
    Łotwa
    transport kolejowy
    przepływ ładunków
    automatyczna rejestracja numerów wagonów
    automatyczna rejestracja numerów pociągów
    Opis:
    In the article the RFID System (Radio Frequency Identification) is presented.
    Źródło:
    Autobusy : technika, eksploatacja, systemy transportowe; 2017, 18, 6; 1474-1476, CD
    1509-5878
    2450-7725
    Pojawia się w:
    Autobusy : technika, eksploatacja, systemy transportowe
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical predictions of laminar flow and free convection heat transfer from an isothermal vertical flat plate
    Autorzy:
    Belhocine, Ali
    Stojanovic, Nadica
    Abdullah, Oday Ibraheem
    Powiązania:
    https://bibliotekanauki.pl/articles/27309866.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    free convective flow
    vertical flat plate
    similarity solution
    boundary layer flow
    dimensionless temperature
    Prandtl number
    Runge-Kutta method
    swobodny przepływ konwekcyjny
    rozwiązanie podobieństwa
    przepływ warstwy granicznej
    bezwymiarowa temperatura
    numer Prandtla
    Metoda Runge-Kutty
    Opis:
    In this present work, the laminar free convection boundary layer flow of a two-dimensional fluid over the vertical flat plate with a uniform surface temperature has been numerically investigated in detail by the similarity solution method. The velocity and temperature profiles were considered similar to all values and their variations are as a function of distance from the leading edge measured along with the plate. By taking into account this thermal boundary condition, the system of governing partial differential equations is reduced to a system of non-linear ordinary differential equations. The latter was solved numerically using the Runge-Kutta method of the fourth-order, the solution of which was obtained by using the FORTRAN code on a computer. The numerical analysis resulting from this simulation allows us to derive some prescribed values of various material parameters involved in the problem to which several important results were discussed in depth such as velocity, temperature, and rate of heat transfer. The definitive comparison between the two numerical models showed us an excellent agreement concerning the order of precision of the simulation. Finally, we compared our numerical results with a certain model already treated, which is in the specialized literature.
    Źródło:
    Archive of Mechanical Engineering; 2022, LXIX, 4; 749--773
    0004-0738
    Pojawia się w:
    Archive of Mechanical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analogy between thermal and mass diffusion effects of a free convective flow in rectangular enclosure
    Autorzy:
    Ambethkar, Vusala
    Powiązania:
    https://bibliotekanauki.pl/articles/1839737.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
    Tematy:
    free convective flow
    thermal diffusion effects
    mass diffusion effects
    rectangular enclosure
    average Nusselt number
    average Sherwood number
    empirical correlations
    swobodny przepływ konwekcyjny
    efekty dyfuzji termicznej
    efekty dyfuzji masowej
    korelacje empiryczne
    średnia liczba Sherwooda
    średnia liczba Nusselta
    Opis:
    In this investigation, the analogy between thermal and mass diffusive effects of a free convective flow in a rectangular enclosure is emphasized. The upwind finite volume method is used to discretize the governing equations of the continuity, momentum, energy and mass transfer. The novelty in this exploration is to appropriately modify the well-known Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) algorithm so that it suits to the present problem and thereby, the new flow variables such as the temperature and the concentration are computed. An empirical correlation for the average Sherwood number (Sh) that does not exist in literature is suggested in this work. The average Sherwood numbers for distinct fluids (gases and liquids) are calculated, and mass diffusion effects within the horizontal rectangle are analyzed. The average Nusselt numbers (Nu) are calculated for distinct fluids such as liquids (Pr ≫1), liquid metals (Pr≪1) and gases (Pr < 1) for different Rayleigh numbers in the range of 3x105 ≤ RaL ≤ 7x10 9 from relevant empirical correlations existing in the literature. Accordingly, the thermal diffusion effects within the horizontal rectangle are analyzed.
    Źródło:
    Journal of Applied Mathematics and Computational Mechanics; 2020, 19, 4; 5-20
    2299-9965
    Pojawia się w:
    Journal of Applied Mathematics and Computational Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analogy between thermal and mass diffusion effects of a free convective flow in rectangular enclosure
    Autorzy:
    Ambethkar, Vusala
    Powiązania:
    https://bibliotekanauki.pl/articles/1839750.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
    Tematy:
    free convective flow
    thermal diffusion effects
    mass diffusion effects
    rectangular enclosure
    average Nusselt number
    average Sherwood number
    empirical correlations
    swobodny przepływ konwekcyjny
    efekty dyfuzji termicznej
    efekty dyfuzji masowej
    korelacje empiryczne
    średnia liczba Sherwooda
    średnia liczba Nusselta
    Opis:
    In this investigation, the analogy between thermal and mass diffusive effects of a free convective flow in a rectangular enclosure is emphasized. The upwind finite volume method is used to discretize the governing equations of the continuity, momentum, energy and mass transfer. The novelty in this exploration is to appropriately modify the well-known Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) algorithm so that it suits to the present problem and thereby, the new flow variables such as the temperature and the concentration are computed. An empirical correlation for the average Sherwood number (Sh) that does not exist in literature is suggested in this work. The average Sherwood numbers for distinct fluids (gases and liquids) are calculated, and mass diffusion effects within the horizontal rectangle are analyzed. The average Nusselt numbers (Nu) are calculated for distinct fluids such as liquids (Pr ≫1), liquid metals (Pr≪1) and gases (Pr < 1) for different Rayleigh numbers in the range of 3x105 ≤ RaL ≤ 7x10 9 from relevant empirical correlations existing in the literature. Accordingly, the thermal diffusion effects within the horizontal rectangle are analyzed.
    Źródło:
    Journal of Applied Mathematics and Computational Mechanics; 2020, 19, 4; 5-20
    2299-9965
    Pojawia się w:
    Journal of Applied Mathematics and Computational Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effects of radiation and Eckert number on MHD flow with heat transfer rate near a stagnation point over a non-linear vertical stretching sheet
    Autorzy:
    Fenuga, O. J.
    Hassan, A. R.
    Olanrewaju, P. O.
    Powiązania:
    https://bibliotekanauki.pl/articles/264652.pdf
    Data publikacji:
    2020
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    przepływ magnetohydrodynamiczny
    transfer ciepła
    transfer masy
    liczba Eckerta
    MHD flow
    heat and mass transfer
    radiation
    Eckert number stagnation–point
    non-linear vertical stretching sheet
    Opis:
    This work investigates the effects of radiation and Eckert number on an MHD flow with heat transfer rate near a stagnation-point region over a nonlinear vertical stretching sheet. Using a similarity transformation, the governing equations are transformed into a system of ordinary differential equations which are solved numerically using the sixth order Runge-Kutta method with shooting technique. Tabular and graphical results are provided to examine the physical nature of the problem. Heat transfer rate at the surface decreases with radiation, Eckert number and as radiation increases, the flow temperature also increases for velocity ratio parameters […].
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2020, 25, 1; 27-36
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Granica laminarnego przepływu wody w obsypce żwirowej studni eksploatacyjnej
    The boundary of the laminar water flow in the filter pack of a pumping well
    Autorzy:
    Matyka, M.
    Mądrala, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/2075640.pdf
    Data publikacji:
    2017
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    obsypka żwirowa
    pompy wodne
    przepływ w ośrodku porowatym
    matoda LBM
    numer uczestnictwa
    filter packs
    water wells
    pore-scale flow
    Lattice Boltzmann Method
    participation number
    Opis:
    Structural changes of aquifers, resulting from a higher velocity of water entering a screen, may occur in the zone around wells ’ screen. Well discharge rate equations assume a laminar flow and agreement with the Darcy s law. Thus, the admissible velocity of water entering the screen should not exceed a certain limit. In this research, the microstructure of water flow velocity in the well s filter pack was studied. We took a picture of the internal structure of the aquifer s pore media in an in situ undisturbed soil sample. Because of the lack of a clear definition of the characteristic length scale in the Reynolds number, we propose to use additionally n - a dimensionless value describing the distribution of kinetic energy in the system - as a criterion for changing the flow nature. We based the study on numerical simulations offluid flow in pore space. We used the Lattice-Boltzmann Method (LBM) to simulate water flow in the filtered zone. We find that in a real porous system of the filter pack with a porosity of n = 0.49, as opposed to highly porous material at n = 0.9, the values of n increase with the decreasing and increasing Reynolds number. The distribution of the velocity field in the analyzed sections also shows the formation ofprivileged waterflow paths and the formation ofvortex structures for high flow velocities.
    Źródło:
    Przegląd Geologiczny; 2017, 65, 11/2; 1334--1338
    0033-2151
    Pojawia się w:
    Przegląd Geologiczny
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Axisymmetric mixed convective MHD flow over a slender cylinder in the presence of chemically reaction
    Autorzy:
    Prasad, K. V.
    Vaidya, H.
    Vajravelu, K.
    Datti, P. S.
    Umesh, V.
    Powiązania:
    https://bibliotekanauki.pl/articles/264807.pdf
    Data publikacji:
    2016
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    pole magnetyczne
    reakcja chemiczna
    przepływ konwekcyjny
    metoda Keller-box
    Keller-box method
    Grashof number
    slender cylinder
    convective flow
    magnetic field
    chemical reaction
    heat and mass transfer
    Opis:
    The present analysis is focused on the study of the magnetic effect on coupled heat and mass transfer by mixed convection boundary layer flow over a slender cylinder in the presence of a chemical reaction. The buoyancy effect due to thermal diffusion and species diffusion is investigated. Employing suitable similarity transformations, the governing equations are transformed into a system of coupled non-linear ordinary differential equations and are solved numerically via the implicit, iterative, second order finite difference method. The numerical results obtained are compared with the available results in the literature for some special cases and the results are found to be in excellent agreement. The velocity, temperature, and the concentration profiles are presented graphically and analyzed for several sets of the pertinent parameters. The pooled effect of the thermal and mass Grashof number is to enhance the velocity and is quite the opposite for temperature and the concentration fields.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2016, 21, 1; 121-141
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical solution of MHD channel flow in a porous medium with uniform suction and injection in the presence of an inclined magnetic field
    Autorzy:
    Chutia, Muhim
    Powiązania:
    https://bibliotekanauki.pl/articles/2175529.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
    Tematy:
    MHD flow
    Brinkman equation
    permeability parameter
    Hartmann number
    uniform suction and injection
    finite difference method
    przepływ MHD
    równanie Brinkmana
    parametr przepuszczalności
    liczba Hartmanna
    równomierne ssanie i wtrysk
    metoda różnic skończonych
    Opis:
    In this paper, the steady fully developed MHD flow of a viscous incompressible electrically conducting fluid through a channel filled with a porous medium and bounded by two infinite walls is investigated numerically for the cases (i) Poiseuille flow and (ii) Couette-Poiseuille flow; with uniform suction and injection at the walls in the presence of an inclined magnetic field. The Brinkman equation is used for the flow in the porous channel and solved numerically using the finite difference method. Numerical results are obtained for velocity. The effects of various dimensionless parameters such as Hartmann number (M), suction/injection parameter (S), permeability parameter (α) and angle of inclination (θ) on the flow are discussed and presented graphically.
    Źródło:
    Journal of Applied Mathematics and Computational Mechanics; 2022, 21, 2; 5--13
    2299-9965
    Pojawia się w:
    Journal of Applied Mathematics and Computational Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Simulation study on strength and failure characteristics of coal-rock composite sample with coal persistent joint
    Badanie symulacyjne charakterystyk wytrzymałościowych próbki kompozytowej złożonej z materiału skalnego oraz węgla w którym występują płaszczyzny łupliwości
    Autorzy:
    Yin, Dawei
    Chen, Shaojie
    Chen, Bing
    Xia, Zhiguo
    Powiązania:
    https://bibliotekanauki.pl/articles/219275.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    symulacja PFC
    próbka kompozytowa złożona z węgla i materiału skalnego
    spoistość węgla
    charakterystyka wytrzymałościowa
    ewolucja mikro-pęknięć
    particle flow simulation
    coal-rock composite sample
    coal persistent joint
    strength and failure characteristics
    microcrack number evolution
    Opis:
    Dynamic Mine disasters can be induced by the instability and failure of a composite structure of rock and coal layers during coal mining. Coal seam contains many native defects, severely affecting the instability and failure of the compound structure. In this study, the effects of coal persistent joint on the strength and failure characteristics of coal-rock composite samples were evaluated using PFC2D software. The results show that with the increase of included angle α between the loading direction and joint plane direction, the uniaxial compressive stress (UCS) and peak strain of composite samples first decrease and then gradually increase. The elastic moduli of composite samples do not change obviously with α. The peak strain at α of 45° is the lowest, and the UCS at α of 30° is the smallest. This is inconsistent with theoretical analysis of lowest UCS at α of 45°. This is because that the local stress concentration caused by the motion inconformity of composite samples may increase the average axial stress of upper wall in PFC2D software. Moreover, the coal persistent joint promotes the transformation from the unstable crack expansion to the macro-instability of composite samples, especially at α of 30° and 45°. The majority of failures for composite samples occur within the coal, and no obvious damage is observed in rock. Their failure modes are shear failure crossing or along the coal persistent joint. The failure of composite sample at α of 30° is a mixed failure, including the shear failure along the persistent joint in coal and tensile failure of rock induced by the propagation of coal persistent joint.
    Niekorzystne zjawiska dynamiczne w kopalniach mogą być wywołane przez niestabilność i pękanie struktur kompozytowych złożonych z warstw węgla i materiałów skalnych w trakcie eksploatacji górniczej. W złożu węgla ujawnić się mogą liczne defekty wewnętrzne, które w poważnym stopniu rzutują na stabilność i wytrzymałość złożonej struktury. W pracy tej zbadano wpływ spoistości węglu (występowania powierzchni łupliwości) na charakterystykę wytrzymałościową próbki kompozytowej złożonej z węgla i skały z wykorzystaniem oprogramowania PCF 2D. Wyniki symulacji wskazują, że wraz ze wzrostem kąta α pomiędzy kierunkiem działania obciążenia a płaszczyzną łupliwości, jednoosiowe naprężenie ściskające oraz maksymalne odkształcenie próbki kompozytowej w pierwszym etapie zmniejszą się, a następnie zaczną stopniowo wzrastać. Moduł sprężystości próbek kompozytowych nie ulega zmianie wraz ze zmianą kąta α. Maksymalne odkształcenie będzie najmniejsze dla kąta α równego 45°, z kolei jednoosiowe naprężenie ściskające zarejestrowane dla 30° okaże się najniższe. Wyniki te nie wykazują zgodności z wynikami analiz teoretycznych, przewidujących iż najniższe wartości jednoosiowego naprężenia ściskającego powinny wystąpić dla kąta 45°. Dzieje się tak dlatego, że lokalne koncentracje naprężeń wskutek odmienności zachowania poszczególnych składników próbki w trakcie ruchu powodować mogą wzrost średniego naprężenia osiowego ściany górnej, co uwzględnia model z wykorzystaniem oprogramowania PFC 2D. Ponadto, istnienie ciosu i płaszczyzn łupliwości sprawia, że niestabilne i propagujące szczeliny ulegają przekształceniu w makro- niestabilności próbek kompozytowych, zwłaszcza przy kącie α równym 30° i 45°. Większość pęknięć powstających w próbkach kompozytowych występuje w części węglowej, w pozostałych skałach nie notuje się poważniejszych uszkodzeń. Pęknięcia zmęczeniowe w części złożonej z materiału skalnego odbywają się wskutek działania naprężeń ścinających wzdłuż lub w poprzez płaszczyzny łupliwości. Pękanie zmęczeniowe próbki kompozytowej przy kącie α równym 30° jest procesem złożonym, obejmującym pękanie wskutek naprężeń ścinających działających wzdłuż płaszczyzny łupliwości w węglu oraz naprężeń rozciągających działających na część próbki złożoną z materiału skalnego, wskutek propagacji pęknięcia.
    Źródło:
    Archives of Mining Sciences; 2019, 64, 3; 609-623
    0860-7001
    Pojawia się w:
    Archives of Mining Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-44 z 44

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