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    Wyświetlanie 1-12 z 12
    Tytuł:
    Analysis of transient natural convective flow of a nanofluid in a vertical tube
    Autorzy:
    Jha, Basant K.
    Chitumu, Ali J.
    Oni, Michael O.
    Powiązania:
    https://bibliotekanauki.pl/articles/1839829.pdf
    Data publikacji:
    2021
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    nanociecze
    naturalna konwekcja
    wymiana ciepła
    nanofluid
    transient
    natural convection
    heat transfer
    vertical tube
    Opis:
    An analysis into the transient natural convective flow of a nanofluid in a vertical tube is made. The governing equations of momentum, heat transfer and nanoparticle volume fraction are deduced, and the influence of the thermophoresis parameter and Brownian motion is incorporated. By direct integration and variation of the parameter, analytical solutions are obtained for flow formation and heat/mass transfer at steady-state. On the other hand, due to the complexity of same problem at transient state, a numerical solution is used to solve the discretized equations of motion using the implicit finite difference technique. The influence of the thermophoresis parameter and Brownian motion is noted and well discussed. For accuracy check, a numerical comparison is made between the steady state and transient state solution at large time; this comparison gives an excellent agreement. The role of various principal parameters on velocity profile, temperature, concentration of nanoparticles, Sherwood and Nusselt numbers are presented graphically and well discussed. It is noted that the buoyancy ratio decreases the fluid velocity significantly.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2021, 26, 2; 31-46
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Heat transfer by natural convection from a heated square inner cylinder to its elliptical outer enclosure utilizing nanofluids
    Autorzy:
    Bouras, Abdelkrim
    Taloub, Djedid
    Driss, Zied
    Debka, Siham
    Powiązania:
    https://bibliotekanauki.pl/articles/2174195.pdf
    Data publikacji:
    2022
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    konwekcja naturalna
    nanociecz
    ułamek objętościowy
    natural convection
    Rayleigh number
    nanofluid
    volume fraction
    square elliptical
    Opis:
    In this paper a numerical study of natural convection of stationary laminar heat transfers in a horizontal ring between a heated square inner cylinder and a cold elliptical outer cylinder is presented. A Cu-water nanofluid flows through this annular space. Different values of the Rayleigh number and volume fraction of nanoparticles are studied. The system of equations governing the problem was solved numerically by the fluent calculation code based on the finite volume method and on the Boussinesq approximation. The interior and exterior surfaces are kept at constant temperature. The study is carried out for Rayleigh numbers ranging from 310 to 510. We have studied the effects of different Rayleigh numbers and volume fraction of nanoparticles on natural convection. The results are presented as isotherms, isocurrents, and local and mean Nusselt numbers. The aim of this study is to study the influence of the thermal Rayleigh number and volume fraction of nanoparticles on the heat transfer rate.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2022, 27, 2; 22--34
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Performance of four different nanoparticles in boundary layer flow over a stretching sheet in porous medium driven by buoyancy force
    Autorzy:
    Ammani Kuttan, B.
    Manjunatha, S.
    Jayanthi, S.
    Gireesha, B. J.
    Powiązania:
    https://bibliotekanauki.pl/articles/264960.pdf
    Data publikacji:
    2020
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    konwekcja naturalna
    nanociecze
    rozwiązania numeryczne
    natural convection
    porous parameter
    nanofluid
    numerical solutions
    volume fraction
    Opis:
    This contemporary work explores the theoretical analysis of energy transfer performance of distinct nanoparticles (silver, copper, aluminium oxide and titanium oxide) adjacent to a moving surface under the influence of a porous medium which is driven by the buoyancy force. A mathematical model is presented which is converted to similarity equations by employing similarity transformation. The condensed nonlinear equations were approximated by the iterative method called RKF 45th-order. The flow and energy transference characteristics are explained through graphs and tabulated values. The notable findings are: silver- water is an appropriate nanofluid for enhancing the thermal conductivity of the base fluid. Titanium oxide – water shows a lower fluid flow movement due to porosity.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2020, 25, 2; 1-10
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Role of induced magnetic field on transient natural convection flow in a vertical channel: The Riemann sum approximation approach
    Autorzy:
    Jha, B. K.
    Sani, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/266260.pdf
    Data publikacji:
    2015
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    induced magnetic field
    natural convection flow
    Riemann-sum approximation
    pole magnetyczne
    przepływ konwekcyjny
    twierdzenie Laplace'a
    Opis:
    This paper investigates the role of induced magnetic field on a transient natural convection flow of an electrically conducting, incompressible and viscous fluid in a vertical channel formed by two infinite vertical parallel plates. The transient flow formation inside the channel is due to sudden asymmetric heating of Chanel walls. The time dependent momentum, energy and magnetic induction equations are solved semi-analytically using the Laplace transform technique along with the Riemann-sum approximation method. The solutions obtained are validated by comparisons with the closed form solutions obtained for the steady states which hale been derived separately and also by the implicit finite difference method. Graphical results for the temperature, velocity, induced magnetic field, current density, and skin-friction based on the semi-analytical solutions are presented and discussed.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2015, 20, 1; 65-85
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of Rayleigh number on internal eccentricity in a heated horizontal elliptical cylinder to its coaxial square enclosure
    Autorzy:
    Bouras, Abdelkrim
    Taloub, Djedid
    Driss, Zied
    Powiązania:
    https://bibliotekanauki.pl/articles/1839785.pdf
    Data publikacji:
    2020
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    konwekcja naturalna
    płyn Newtona
    liczba Rayleigha
    natural convection
    newtonian fluid
    geometry ratio
    Rayleigh number
    elliptical cylinder
    Opis:
    This paper deals with numerical investigation of a natural convective flow in a horizontal annular space between a heated square inner cylinder and a cold elliptical outer cylinder with a Newtonian fluid. Uniform temperatures are imposed along walls of the enclosure. The governing equations of the problem were solved numerically by the commercial code Fluent, based on the finite volume method and the Boussinesq approximation. The effects of Geometry Ratio GR and Rayleigh numbers on fluid flow and heat transfer performance are investigated. The Rayleigh number is varied from 103 to 106. Throughout the study the relevant results are presented in terms of isotherms, and streamlines. From the results, we found that the increase in the Geometry Ratio B leads to an increase of the heat transfer coefficient. The heat transfer rate in the annulus is translated in terms of the average Nusselt numbers along the enclosure's sides. Tecplot 7 program was used to plot the curves which cleared these relations and isotherms and streamlines which illustrate the behavior of air through the channel and its variation with other parameters. The results for the streamlines, isotherms, local and average Nusselt numbers average Nusselt numbers are compared with previous works and show good agreement.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2020, 25, 3; 17-29
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    MHD natural convection flow with radiative heat transfer past an impulsively moving vertical plate with ramped temperature in the presence of hall current and thermal diffusion
    Autorzy:
    Seth, G. S.
    Mahato, G. K.
    Sarkar, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/955266.pdf
    Data publikacji:
    2013
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    konwekcja naturalna
    dyfuzja termiczna
    promieniowanie cieplne
    MHD natural convection
    Hall current
    ramped temperature
    thermal diffusion
    thermal radiation
    Opis:
    An investigation on an unsteady MHD natural convection flow with radiative heat transfer of a viscous, incompressible, electrically conducting and optically thick fluid past an impulsively moving vertical plate with ramped temperature in a porous medium in the presence of a Hall current and thermal diffusion is carried out. An exact solution of momentum and energy equations, under Boussinesq and Rosseland approximations, is obtained in a closed form by the Laplace transform technique for both ramped temperature and isothermal plates. Expressions for the skin friction and Nusselt number for both ramped temperature and isothermal plates are also derived. The numerical values of fluid velocity and fluid temperature are displayed graphically versus the boundary layer coordinate y for various values of pertinent flow parameters for both ramped temperature and isothermal plates. The numerical values of the skin friction due to primary and secondary flows are presented in tabular form for various values of pertinent flow parameters.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2013, 18, 4; 1201-1220
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigations of Couette flow unsteady radiative convective heat transfer in a vertical channel using the generalized method of lines (MOL)
    Autorzy:
    Sowayan, Ahmed S.
    Powiązania:
    https://bibliotekanauki.pl/articles/2174210.pdf
    Data publikacji:
    2022
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    promieniowanie
    konwekcja naturalna
    metoda Runge-Kutty
    vertical channel
    radiation
    natural convection
    method of lines (MOL)
    Runge-Kutta method
    Opis:
    This study describes a very efficient and fast numerical solution method for the non-steady free convection flow with radiation of a viscous fluid between two infinite vertical parallel walls. The method of lines (MOL) is used together with the Runge-Kutta ODE Matlab solver to investigate this problem numerically. The presence of radiation adds more stiffness and numerical complexity to the problem. A complete derivation in dimensionless form of the governing equations for momentum and energy is also included. A constant heat flux condition is applied at the left wall and a transient numerical solution is obtained for different values of the radiation parameter (R). The results are presented for dimensionless velocity, dimensionless temperature and Nusselt number for different values of the Prandtl number (Pr), Grashof number (Gr), and the radiation parameter (R). As expected, the results show that the convection heat transfer is high when the Nusselt number is high and the radiation parameter is low. It is also shown that the solution method used is simple and efficient and could be easily adopted to solve more complex problems.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2022, 27, 3; 199--211
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Thermal analysis of a fully wet porous radial fin with natural convection and radiation using the spectral collocation method
    Autorzy:
    Khani, F.
    Darvishi, M. T.
    Gorla, R. S. R.
    Gireesha, B. J.
    Powiązania:
    https://bibliotekanauki.pl/articles/264453.pdf
    Data publikacji:
    2016
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    porowatość
    naturalna konwekcja
    promieniowanie
    analiza termiczna
    wet porous radial fin
    natural convection
    radiation
    thermal analysis
    spectral collocation method
    Opis:
    Heat transfer with natural convection and radiation effect on a fully wet porous radial fin is considered. The radial velocity of the buoyancy driven flow at any radial location is obtained by applying Darcy’s law. The obtained non-dimensionalized ordinary differential equation involving three highly nonlinear terms is solved numerically with the spectral collocation method. In this approach, the dimensionless temperature is approximated by Chebyshev polynomials and discretized by Chebyshev-Gausse-Lobatto collocation points. A particular algorithm is used to reduce the nonlinearity of the conservation of energy equation. The present analysis characterizes the effect of ambient temperature in different ways and it provides a better picture regarding the effect of ambient temperature on the thermal performance of the fin. The profiles for temperature distributions and dimensionless base heat flow are obtained for different parameters which influence the heat transfer rate.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2016, 21, 2; 377-392
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Natural convection and radiation in a radial porous fin with variable thermal conductivity
    Autorzy:
    Darvishi, M. T.
    Kani, F.
    Gorla, R. S. R.
    Powiązania:
    https://bibliotekanauki.pl/articles/955178.pdf
    Data publikacji:
    2014
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    konwekcja naturalna
    promieniowanie
    wydajność cieplna
    metoda kolokacji
    porous radial fin
    natural convection
    radiation
    thermal performance
    spectral collocation method
    Opis:
    In this study, the effects of radiation and convection heat transfer in a radial porous fin are considered. The geometry considered is that of a rectangular profile fin. The porous fin allows the flow to infiltrate through it and solid-fluid interaction takes place. This study is performed using Darcy’s model to formulate the heat transfer equation. The thermal conductivity is assumed to be a function of temperature. The effects of the natural convection parameter Nc , radiation parameter Nr and thermal conductivity parameter m on the dimensionless temperature distribution and heat transfer rate are discussed. The results suggest that the radiation transfers more heat than a similar model without radiation.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2014, 19, 1; 27-37
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Unsteady/steady natural convection flow of reactive viscous fluid in a vertical annulus
    Autorzy:
    Jha, B. K.
    Samaila, A. K.
    Ajibade, A. O.
    Powiązania:
    https://bibliotekanauki.pl/articles/265663.pdf
    Data publikacji:
    2013
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    konwekcja naturalna
    lepki płyn
    egzotermiczna otulina
    unsteady/steady natural convection flow
    reactive viscous fluid
    exothermic
    open ended vertical annulus
    Opis:
    This paper presents both analytical and numerical analyses of a fully developed unsteady/steady natural convection flow of a reactive viscous fluid in an open ended vertical annulus. Analytical expressions for velocity, temperature, skin-friction and rate of heat transfer are obtained after simplifying and solving the governing differential equations with reasonable approximations. The interesting result found in this study is that an increase in non-dimensional time (t) , increases both temperature and velocity profiles until a steady-state value is attained. Subsequent results obtained by numerical calculations show excellent agreement with analytical results.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2013, 18, 1; 73-83
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Natural convection in a hydrodynamically and thermally anisotropic non-rectangular porous cavity: effect of internal heat generation/absorption
    Autorzy:
    Chandran, P.
    Sacheti, N. C.
    Bhadauria, B. S.
    Singh, A. K.
    Powiązania:
    https://bibliotekanauki.pl/articles/264468.pdf
    Data publikacji:
    2018
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    konwekcja naturalna
    materiały porowate
    przepuszczalność
    dyfuzyjność cieplna
    źródło ciepła
    natural convection
    trapezoidal cavity
    porous medium
    permeability
    thermal diffusivity
    Darcy's law
    heat source/sink
    Opis:
    Laminar natural convection in a trapezoidal porous vertical cavity has been investigated in this work. It is assumed that the porous enclosure is filled up with a permeable material subject to hydrodynamic and thermal anisotropy, the flow being governed by the Darcy law as applicable to a non-isotropic medium. It is further assumed that (i) there is heating at the left vertical wall and cooling at the right wall of the enclosure and (ii) the flow domain is subject to the presence of heat source or heat sink. The partial differential equations governing the resulting free convection have been solved numerically in the non-dimensional forms. There arises a number of parameters relating to buoyancy, internal heating, cavity aspect ratio and inclination of the upper surface to the horizontal. The influence of these parameters has been illustrated and analyzed through contours of streamlines and isotherms. We have also discussed the role of internal heating as well as anisotropy on the heat transfer characteristics.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2018, 23, 3; 595-609
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    FEM simulation of triple diffusive natural convection along inclined plate in porous medium: prescribed surface heat, solute and nanoparticles flux
    Autorzy:
    Goyal, M.
    Goyal, R
    Bhargava, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/266289.pdf
    Data publikacji:
    2017
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    triple diffusive
    natural convection
    nanofluid
    binary base fluid
    porous medium
    solutal concentration flux
    nanoparticle concentration flux
    inclined plate
    naturalna konwekcja
    płyn bazowy
    nanocząstki
    Opis:
    In this paper, triple diffusive natural convection under Darcy flow over an inclined plate embedded in a porous medium saturated with a binary base fluid containing nanoparticles and two salts is studied. The model used for the nanofluid is the one which incorporates the effects of Brownian motion and thermophoresis. In addition, the thermal energy equations include regular diffusion and cross-diffusion terms. The vertical surface has the heat, mass and nanoparticle fluxes each prescribed as a power law function of the distance along the wall. The boundary layer equations are transformed into a set of ordinary differential equations with the help of group theory transformations. A wide range of parameter values are chosen to bring out the effect of buoyancy ratio, regular Lewis number and modified Dufour parameters of both salts and nanofluid parameters with varying angle of inclinations. The effects of parameters on the velocity, temperature, solutal and nanoparticles volume fraction profiles, as well as on the important parameters of heat and mass transfer, i.e., the reduced Nusselt, regular and nanofluid Sherwood numbers, are discussed. Such problems find application in extrusion of metals, polymers and ceramics, production of plastic films, insulation of wires and liquid packaging.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2017, 22, 4; 883--900
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-12 z 12

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