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Tytuł:
Skin friction estimation in a strong decelerating flow
Autorzy:
Dróżdż, A.
Elsner, W.
Sikorski, D.
Powiązania:
https://bibliotekanauki.pl/articles/279383.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
turbulent boundary layer
separation
oil-film interferometry
Clauser chart
Opis:
The paper presents the analysis of the turbulent boundary layer developed on a flat plate subjected to an Adverse Pressure Gradient (APG) and approaching separation. The aim of the study is to examine the effects of pressure gradient on a non-equilibrium boundary layer while indicating local areas of the equilibrium flow. The emphasis is on the analysis of mean flow velocity and the estimation of skin friction. It is known that accurate measurements of skin friction were considered as a difficult and demanding task despite of various measuring techniques available. A great challenge is especially the measurement of a strong decelerated turbulent boundary layer because of low shear stress and possible large measuring errors. To date, the oil film or oil drop interferometry technique, because of its high accuracy, has become a basis of turbulent-boundary-layer research. In our research, this technique has been used as a reference method for comparing with the traditional Clauser chart method, which generally is considered as not suitably for non-canonical flows. In the paper, however, a correction of the method is proposed, which allows one to increase its range of applicability. This corrected Clauser chart method (CCCM) involves only one iteration while other proposed in the literature methods employ a twofold iterative procedure. The comparison of the methods for the non-canonical turbulent boundary layer, i.e. adverse pressure gradient with a strong flow history effect has been presented. It has been shown that CCCM can be successfully used for small and medium pressure gradients, where the Clauser-Rotta pressure gradient parameter β does not exceed level close to 11.
Źródło:
Journal of Theoretical and Applied Mechanics; 2018, 56, 2; 365-376
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of the diagnostic plot in estimation of the skin friction in turbulent boundary layer under an adverse pressure gradient
Autorzy:
Niegodajew, P.
Dróżdż, A.
Elsner, W.
Powiązania:
https://bibliotekanauki.pl/articles/38622693.pdf
Data publikacji:
2021
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
turbulent boundary layer
friction velocity
Clauser-chart
adverse pressure gradient
diagnostic plot
Opis:
The paper concerns the problem of determining friction velocity in wallbounded flows affected by an adverse pressure gradient (APG). In the work of Niegodajew et al. [22] the corrected Clauser chart method (CCCM) for such flow conditions was proposed. This approach utilises the mean velocity profiles and turbulence intensity profiles to accurately estimate the friction velocity. In another work, Drózdz et al. [27] presented a modified version of the diagnostic-plot scaling (DPS) which allows for direct reconstruction of turbulence intensity profiles based on the local mean velocity profile, even when the flow is affected by a strong pressure gradient. This paper is aimed at verifying whether, when combining both of these methods (i.e. DPS and CCCM), the friction velocity can be accurately determined for APG flow conditions and one can possibly take advantage from both methods. The analysis revealed that the new approach is able to predict the friction velocity with uncertainty less than 5% for all the considered cases for the Clauser–Rotta parameter β < 17. Lastly, DPS-CCCM was also confronted with two empirical approaches (from available literature) allowing for estimation of the friction velocity under APG conditions. The performance of DPS-CCCM was found to be better than the ones of two other empirical approaches.
Źródło:
Archives of Mechanics; 2021, 73, 2; 201-215
0373-2029
Pojawia się w:
Archives of Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Skin and toe resistance mobilisation of pile during laboratory static load test
Autorzy:
Meyer, Z.
Żarkiewicz, K.
Powiązania:
https://bibliotekanauki.pl/articles/178958.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
pile
static load test
skin friction
toe resistance
Opis:
This article shows the mathematical method to determine the lateral stress on the shaft and toe resistance of pile using the new approach. The method was originally invented by Meyer and Kowalow for the static load test. The approximation curve was used for the estimation of both settlement curve and toe resistance curve of the pile. The load applied at the head of the pile is balanced by the sum of two components: the resistance under the toe of the pile and the skin friction. Therefore, the settlement curve is compilation of two factors: the skin friction curve and the resistance under toe curve. The analysis was based on the verification of the methods using laboratory experiments, that is, static load tests. The results of the research allowed to determine the relationship between parameters of the Meyer-Kowalow curve. On the basis of the relationships, it was possible to determine the skin friction and the toe resistance of the pile. Mathematical analysis of curve parameters allowed to determine the influence of the toe resistance on the settlement.
Źródło:
Studia Geotechnica et Mechanica; 2018, 40, 1; 1-5
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of pressure work over a semi-infinite vertical oscillating cylinder
Autorzy:
Sarojini, A.
Palani, G.
Powiązania:
https://bibliotekanauki.pl/articles/1839892.pdf
Data publikacji:
2021
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
cylinder
konwekcja naturalna
metoda Cranka-Nicolsona
finite difference
pressure work
oscillating
skin friction
Opis:
An arithmetical methodology is used to study natural convection with properties of pressure work over a semi-infinite vertical oscillating cylinder. The governing partial differential equations are set up and the resulting equations are changed into a non-dimensional form using the proper non-dimensional quantities. The set of non-dimensional partial differential equations is solved arithmetically using a well-organized method known as the Crank-Nicolson method. The velocity, as well as temperature profiles for different values of parameters are studied with the assistance of graphs.
Źródło:
International Journal of Applied Mechanics and Engineering; 2021, 26, 1; 215-225
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The importance of the law of the wall
Autorzy:
Mandal, B. C.
Mazumdar, H. P.
Powiązania:
https://bibliotekanauki.pl/articles/265857.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
boundary layer
flat plate
friction factor
skin friction
warstwa graniczna
współczynnik tarcia
przepływ rurowy
Opis:
This paper reports some results of turbulent boundary layer computation. The calculation is made assuming that law of the wall is valid throughout the boundary layer. Simple relations are proposed for friction for a smooth pipe and a flat plate at zero incidence. The results are compared with recent measurements. Encouraging results are obtained for both the cases of flows.
Źródło:
International Journal of Applied Mechanics and Engineering; 2015, 20, 4; 857-869
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Opory tarcia gruntu na powierzchniach bocznych fundamentów głębokich w warunkach odprężonego podłoża
Skin friction between the soil and lateral surface of deep foundation with in the relaxed subsoil
Autorzy:
Skutnik, Z.
Krol, P.
Powiązania:
https://bibliotekanauki.pl/articles/40910.pdf
Data publikacji:
2012
Wydawca:
Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie
Tematy:
fundamenty glebokie
tarcie boczne
podloze odprezone
badania geotechniczne
sondowanie gruntow
badania dylatometryczne
parametry geotechniczne
deep foundation
lateral friction
relaxed subsoil
geotechnical research
soil sounding
dilatometer test
geotechnical parameter
Źródło:
Acta Scientiarum Polonorum. Architectura; 2012, 11, 3
1644-0633
Pojawia się w:
Acta Scientiarum Polonorum. Architectura
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Laboratory research of toe resistance based on static pile load tests in different schemes
Badania laboratoryjne oporu pod podstawą pala na podstawie wyników próbnego obciążenia statycznego pala przeprowadzonych w różnych schematach
Autorzy:
Żarkiewicz, K.
Powiązania:
https://bibliotekanauki.pl/articles/396075.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
pile load test
settlement
skin friction
laboratory research
obciążenie statyczne
osiadanie
opór pobocznicy
badania laboratoryjne
Opis:
Transfer of axial force from the head of a pile to the surrounding soil by skin friction and toe resistance is still uncertain. The results of the static pile load test are usually presented as settlement curve. This curve can be divided into two components: skin friction curve and toe resistance curve according to the settlement. Laboratory research of pile load test was carried out in two schemes: with skin friction and without skin friction. The study proved that the toe resistance with and without skin friction is not the same. Skin friction influence on toe resistance due to settlement. This phenomenon is not usually taken into account, but very often has a significant impact on axially applied load transfer. In the paper results of laboratory pile load tests id, different schemes were presented.
Przekazywanie pionowej siły osiowej przyłożonej w głowicy pala na otaczające podłoże gruntowe jest zagadnieniem wciąż nierozwiązanym i w wielu przypadkach budzącym wiele wątpliwości. Wynik próbnego obciążenia statycznego są zwykle przedstawiane na wykresie w postaci krzywej osiadania pala. Krzywa osiadania może być podzielona na dwie składowe krzywe: krzywą oporu pobocznicy i krzywą oporu podstawy pala w stosunku do osiadania głowicy pala. Badania laboratoryjne próbnych obciążeń statycznych zostały przeprowadzone na palach modelowych, w dwóch schematach obciążenia: z udziałem pobocznicy i bez udziału pobocznicy w przekazywaniu obciążenia przyłożonego w głowicy pala. Wyniki badań wskazują, że opór podstawy pala jest różny w zależności od schematu. W związku z tym istnieje zależność oporu podstawy i pobocznicy pala. W artykule przedstawiono wyniki badań laboratoryjnych wraz z interpretacją.
Źródło:
Civil and Environmental Engineering Reports; 2018, No. 28(1); 172-181
2080-5187
2450-8594
Pojawia się w:
Civil and Environmental Engineering Reports
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Static load test curve analysis based on soil field investigations
Autorzy:
Siemaszko, P.
Meyer, Z.
Powiązania:
https://bibliotekanauki.pl/articles/202201.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
static pile test
skin friction
static load test curve
soil characteristics
badanie statyczne
obciążenie
cechy gleb
Opis:
This paper expands the M-K curve theory with examples of the most commonly mentioned pile-soil mechanics behaviours in the literature and their corresponding κ 2 variations. A brief introduction shows the history of the Meyer-Kowalow theory and its basic assumptions. This is followed by the relationship between in situ investigation CPT results, with parameters C1, C2, Ct used to approximate the load-settlement curve according to the M-K theory. The Meyer-Kowalow curve satisfies asymptotic behaviour for small loads, where linear theory applies, and for limit loads, when pile displacement is out of control. Essential in the description are constant parameters C, which refer to the aggregated Winklers modulus, Ngr limit loads and k, which is crucial for static load test results. For this reason, the authors sought to calculate the κ value based upon soil mechanics principles. This article shows methods for checking statistical mathematical calculations, published earlier by Meyer using CPT investigations. It presents real case calculations and directions for future planned research.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2019, 67, 2; 329-337
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Flow features of thermophoretic MHD viscous fluid flow past a converging channel with heat source and chemical reaction
Autorzy:
Kalita, B. K.
Choudhury, R.
Powiązania:
https://bibliotekanauki.pl/articles/2106445.pdf
Data publikacji:
2021
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
magnetohydrodynamika
płyn lepki
termoforeza
liczba Nusselta
MHD
viscous fluid
heat source
thermophoresis
Nusselt number
skin friction
Opis:
A boundary layer flow of an electrically conducting viscous fluid past a converging channel in the presence of thermophoresis, heat source, chemical reaction, viscous dissipation and simultaneous heat and mass transfer characteristics is studied in the paper. An external magnetic field of uniform strength is applied transversely to the channel. The similarity solution has been used to transform the partial differential equations that represent the problem into a boundary value problem of coupled ordinary differential equations, which in turn are solved numerically using MATLAB’s built in solver bvp4c. Numerical computations are carried out to solve the problem and graphical illustrations are made to get the physical insight of the same. The convergent channel flow problem of an incompressible electrically conducting viscous fluid in the presence of a magnetic field has a wide range of applicability in different areas of engineering, specially in industrial metal casting and control of molten metal flow.
Źródło:
International Journal of Applied Mechanics and Engineering; 2021, 26, 3; 72--83
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Soret and Dufour effects on MHD free convective flow past a vertical porous plate in the presence of heat generation
Autorzy:
Reddy, G. V. R.
Powiązania:
https://bibliotekanauki.pl/articles/264624.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
promieniowanie
wymiana ciepła
wymiana masy
tarcie
radiation
heat and mass transfer
skin-friction
Nusselt number
Sherwood number
Opis:
An MHD fluid flow is examined over a vertical plate in the presence of Dufour and Soret effects. The resulting momentum, energy and concentration equations are then made similar by introducing the usual similarity transformations. These similar equations are then solved numerically using the Runge-Kutta fourth order method with shooting technique. The effects of various parameters on the dimensionless velocity, temperature and concentration profiles as well as the local values of the skin-friction coefficient, the Nusselt number and Sherwood number are displayed graphically and in a tabular form. A comparison with previously published work is obtained and an excellent agreement is found.
Źródło:
International Journal of Applied Mechanics and Engineering; 2016, 21, 3; 649-665
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On diffusion of chemically reactive species in a convective flow past an inclined plate with variable surface temperature and variable mass diffusion
Autorzy:
Kirubavathi, J. D.
Palani, G.
Powiązania:
https://bibliotekanauki.pl/articles/266086.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
metoda różnic skończonych
płyta pochylona
tarcie
chemically reactive species
Nusselt number
skin friction
finite-difference methods
inclined plate
Opis:
A numerical solution of a transient natural convection flow past a semi-infinite inclined plate under the combined buoyancy effects of heat and mass transfer along with chemical reaction is presented herewith. The governing boundary layer equations for the above flow problem for a first order homogeneous chemical reaction are set up and non-dimensionalised. An implicit finite difference method is employed to solve the unsteady, nonlinear, integro and coupled partial differential equation. Numerical results are presented for various parameters occurring in the problem. The unsteady velocity, temperature and concentration profiles, local and average skin friction, Nusselt number and Sherwood number are studied for both a generative and destructive reaction.
Źródło:
International Journal of Applied Mechanics and Engineering; 2016, 21, 4; 905-922
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:
Oscillatory fluid flow and heat transfer through porous medium between parallel plates with inclined magnetic field, radiative heat flux and heat source
Autorzy:
Mehta, T.
Mehta, R.
Mehta, A
Powiązania:
https://bibliotekanauki.pl/articles/265399.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
pole magnetyczne
ciało porowate
promieniowanie
źródło ciepła
oscillatory
inclined magnetic field
porous medium
radiation
heat source
skin-friction coefficient and Nusselt number
Opis:
The aim of the paper is to investigate an oscillatory fluid flow and heat transfer through a porous medium between parallel plates in the presence of an inclined magnetic field, radiative heat flux and heat source. It is assumed that electrical conductivity of the fluid is small and the electromagnetic force produced is very small. The governing coupled equations of motion and energy are solved analytically. Numerical results for the velocity and temperature profiles, local skin friction coefficient and local Nusselt number for various values of physical parameters are discussed numerically and presented graphically.
Źródło:
International Journal of Applied Mechanics and Engineering; 2020, 25, 2; 88-102
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Similarity solution for combined free-forced convection past a vertical porous plate in a porous medium with a convective surface boundary condition
Autorzy:
Garg, P.
Purohit, G. N.
Chaudhary, R. C.
Powiązania:
https://bibliotekanauki.pl/articles/265568.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
płyta porowata
tarcie
ośrodek porowaty
konwekcja
combined convection
fixed vertical porous plate
skin-friction coefficient
Nusselt number
convective surface boundary condition
porous medium
Opis:
This paper studies the mathematical implications of the two dimensional viscous steady laminar combined free-forced convective flow of an incompressible fluid over a semi infinite fixed vertical porous plate embedded in a porous medium. It is assumed that the left surface of the plate is heated by convection from a hot fluid which is at a temperature higher than the temperature of the fluid on the right surface of the vertical plate. To achieve numerical consistency for the problem under consideration, the governing non linear partial differential equations are first transformed into a system of ordinary differential equations using a similarity variable and then solved numerically under conditions admitting similarity solutions. The effects of the physical parameters of both the incompressible fluid and the vertical plate on the dimensionless velocity and temperature profiles are studied and analysed and the results are depicted both graphically and in a tabular form. Finally, algebraic expressions and the numerical values are obtained for the local skin-friction coefficient and the local Nusselt number.
Źródło:
International Journal of Applied Mechanics and Engineering; 2016, 21, 4; 827-836
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Heat transfer of viscoelastic fluid flow due to nonlinear stretching sheet with internal heat source
Autorzy:
Nandeppanavar, M. M.
Siddalingappa, M. N.
Jyoti, H.
Powiązania:
https://bibliotekanauki.pl/articles/265070.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
płyn lepkosprężysty
warstwa graniczna przepływu
rozciąganie
źródło ciepła
przenikanie ciepła
viscoelastic fluid
boundary layer flow
exponential stretching sheet
heat source/sink
heat transfer
skin friction
Opis:
In the present paper, a viscoelastic boundary layer flow and heat transfer over an exponentially stretching continuous sheet in the presence of a heat source/sink has been examined. Loss of energy due to viscous dissipation of the non-Newtonian fluid has been taken into account in this study. Approximate analytical local similar solutions of the highly non-linear momentum equation are obtained for velocity distribution by transforming the equation into Riccati-type and then solving this sequentially. Accuracy of the zero-order analytical solutions for the stream function and velocity are verified by numerical solutions obtained by employing the Runge-Kutta fourth order method involving shooting. Similarity solutions of the temperature equation for non-isothermal boundary conditions are obtained in the form of confluent hypergeometric functions. The effect of various physical parameters on the local skin-friction coefficient and heat transfer characteristics are discussed in detail. It is seen that the rate of heat transfer from the stretching sheet to the fluid can be controlled by suitably choosing the values of the Prandtl number Pr and local Eckert number E, local viscioelastic parameter k1 and local heat source/ sink parameter β.
Źródło:
International Journal of Applied Mechanics and Engineering; 2013, 18, 3; 739-760
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
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