Begell House Inc.
Computational Thermal Sciences: An International Journal
CTS
1940-2503
9
1
2017
GENERAL SOLUTIONS OF CONVECTIVE FLOWS OF MHD CASSON FLUID WITH SLIP AND RADIATIVE HEAT TRANSFER AT THE BOUNDARY
1-11
M.A.
Imran
Department of Mathematics, University of Management and Technology Lahore, Pakistan
Nehad Ali
Shah
Abdus Salam School of Mathematical Sciences GC, University Lahore, Pakistan
K.
Rafique
School of Quantitative Sciences, University Utara Malaysia, 06010 Sintok, Kedah, Malaysia
Ahmad
Sohail
Department of Mathematics, Comsats Attock Campus Attock, Pakistan
Sana
Ejaz
Department of Mathematics, University of Management and Technology Lahore, Pakistan
This paper deals with study of analytic solutions of unsteady free convection flow of MHD Casson fluid over an infinite vertical plate when slip condition, radiation, and porous effect are taken into consideration. The appropriate nondimensional variables are introduced, and the resulting governing equations are solved by means of the Laplace transform technique. The closed-form solutions are obtained for temperature and velocity fields. The rate of heat transfer from the plate to the fluid in terms of Nusselt number is also determined. Some known solutions for Newtonian fluid from the literature are obtained as limiting case. Such kinds of solutions can generate a large class of exact solutions corresponding to different fluid motions with technical relevance. Numerical computations were made by using the software Mathcad for the velocity field only. At the end, we see the influence of slip and other flow parameters on the fluid velocity and observed that the large values of the slip coefficient have an effect of reducing fluid velocity and slow fluid flow. This shows how the slip at the wall affects the fluid flow.
EFFECT OF MOVING FLAT PLATE ON HYDRO-MAGNETIC MIXED CONVECTION IN A POROUS ENCLOSURE WITH SINUSOIDAL HEATING SIDE WALLS AND INTERNAL HEAT GENERATION
13-28
A. Shamadhani
Begum
Department of Mathematics, Bharathiar University, Coimbatore-46, India
N.
Nithyadevi
Department of Mathematics, Bharathiar University, Coimbatore 641046, Tamilnadu, India
This paper examines the influence of uniform magnetic field on mixed convection flow in a rectangular enclosure filled with fluid saturated porous medium with the presence of internal heat generation and is subjected to nonuniform heating. The enclosure model has a mid-horizontal moving plate, adiabatic top and bottom walls, and sinusoidally varying vertical walls. The governing equations and boundary conditions are discretized using the finite volume approach with power law scheme and solved numerically by the SIMPLE algorithm for the pressure-velocity coupling together with the under-relaxation technique. Results are found for the various dimensionless governing parameters, such as Hartmann number, Richardson number, Darcy number, phase deviation, heat generation parameter, and amplitude ratio. Especially, some particular values of Hartmann number show significant influence on the flow structure, heat distribution, velocity fields, and heat transfer rate within the enclosure.
HEAT TRANSFER AND ENTROPY GENERATION DUE TO A NANOFLUID OVER STRETCHING CYLINDER: EFFECTS OF THERMAL STRATIFICATION
29-47
Sameh Elsayed
Ahmed
Department of Mathematics, Faculty of Science, Abha, King Khalid University, Saudi Arabia; Department of Mathematics, Faculty of Science, South Valley University, Qena, Egypt
Shadia S.
Mohamed
Mathematics Department, Faculty of Science, South Valley University, Qena, Egypt
M. A.
Mansour
Department of Mathematics, Assuit University, Faculty of Science, Assuit, Egypt
A.
Mahdy
Mathematics Department, Faculty of Science, South Valley University, Qena, Egypt
In this paper, the effects of thermal stratification and uniform suction/injection on the heat transfer and entropy generation by forced convective flow of nanofluids over a horizontal stretching tube are analyzed. The model used for the nanofluid contains the effects of Brownian motion and thermophoresis. Similarity transformations are used to transform the fundamental governing nonlinear boundary layer equations to a system of nonlinear ordinary differential equations for fitting boundary conditions and those are solved, numerically, using the function bvp4c from the MATLAB package. Also, the effects of the different physical parameters on the velocity, pressure distributions, temperature profiles, and nanoparticles concentration distributions are presented in graphs and used to find the stable system via entropy generation minimization. The values of the skin-friction coefficient and Nusselt number are presented in tables. The obtained results are compared with previously published works and found to be in excellent agreements. The numerical results show that the effect of the suction parameter gives the highest entropy near the surface of the cylinder, while the injection parameter minimizes the entropy generation.
CONVECTING THRESHOLD IN NANOFLUID DRIVEN BY CENTRIFUGAL FORCES IN A ROTATING ANNULAR HELE-SHAW
49-62
K.
Souhar
Laboratory of Energy Engineering, Materials and Systems, ENSA, Ibn Zohr University, Morocco
M.
Kriraa
Department of Civil Engineering and Energetics, ENSA Al-Hoceima, Mohammed I University, Oujda, Morocco
L.
Bammou
Laboratory of Thermodynamics and Energy, Faculty of Sciences, Ibn Zohr University, Morocco
S.
Alami
Laboratory of Thermodynamics and Energy, Faculty of Sciences, Ibn Zohr University, Morocco
J.
Bouchgl
Laboratory of Energy Engineering, Materials and Systems, ENSA, Ibn Zohr University, Morocco
M'barek
Feddaoui
Laboratory of Energy Engineering, Materials and Systems, ENSA, Ibn Zohr University, Morocco
S.
Aniss
Laboratory of Mechanics, Faculty of Sciences Ain Chock, Hassan II University, Morocco
The onset of convection in nanofluid confined within a rotating Hele-Shaw cell is studied by using a linear stability analysis. The model for our nanofluid combines the effects of Brownian motion and thermophoresis where the gravitation is negligible and the convection is driven by centrifugal forces. The linear stability equations are solved numerically to find the critical values of the Rayleigh and wave numbers. The analysis reveals that the curvature parameter and the Eckman number delay the onset of convection, while the nanoparticle concentration Rayleigh number, Lewis number and modified diffusivity ratio hasten the onset of convection.
EFFECTIVE MEDIUM APPROXIMATION FOR CONDUCTIVITY OF UNIDIRECTIONAL COATED-FIBER COMPOSITES
63-76
Bao-Viet
Tran
Construction Engineering Department, University of Transport and Communication, Hanoi, Vietnam;
Research and Application Center for Technology in Civil Engineering, University of Transport and Communication, Hanoi, Vietnam
Duc-Chinh
Pham
VAST, Institute of Mechanics, 264 Doi Can, Hanoi, Vietnam
Thi-Huong-Giang
Nguyen
Faculty of Basic Sciences, University of Transport and Communication, Hanoi, Vietnam
Effective medium approximations are developed to estimate the effective conductivity of unidirectional composites that are composed of coated fiber-inclusions embedded in a continuous matrix phase. The two-phase coated inclusions are substituted by equivalent one-phase inclusions from a dilute solution. Then, usual effective medium approximation schemes are applied to the equivalent medium to estimate the conductivity of original three-phase composites. Applications with numerical and experimental illustrations are given for certain periodic and random composites.
NATURAL CONVECTION INDUCED BY VOLUMETRIC HEATING IN AN INCLINED POROUS CAVITY
77-92
Soufyane
Benmenzer
LESEI Laboratory, Department of Mechanical Engineering, Technology Faculty, Batna University, Algeria
Mohamed
Si-Ameur
LESEI Laboratory, Department of Mechanical Engineering, Technology Faculty, University of Batna 2, Algeria
Numerical and analytical studies are carried out to investigate natural convection in an inclined porous cavity filled with a volumetric heat source. Heat fluxes are imposed on the sidewalls to ensure a cooling process. The Darcy model is taken into account in the mathematical formulation of the problem. The density variation is modeled by Boussinesq approximation as the temperature values are limited. Numerical solutions are obtained for a wide range of governing parameters such as aspect ratio A, Rayleigh number R, inclination angle φ, and the dimensionless heat flux at the left active wall qL. The analytical solution is based on the parallel flow approximation and valid for A » 1. The results elucidate an asymptotic tendency of the rate heat transfer with Rayleigh number. The normalized Nusselt number NuL reach the maximum when φ = 80 deg and qL = 0.75. A good agreement between the analytical model and the numerical simulations is obtained in the case of a tall cavity.