5,536 research outputs found

    Effect of viscous dissipation on natural convection in a non-Darcy porous medium saturated with non-Newtonian fluid of variable viscosity

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    This paper investigates the influence of the effect of viscous dissipation and radiation on natural convection heat transfer from vertical flat plate in a non-Darcy porous media saturated with non-Newtonian fluid of variable viscosity. The wall and the ambient medium are maintained at constant but different levels of temperature. The Ostwald-de Waele power law model is used to characterize the non-Newtonian fluid behavior. The viscosity of the fluid is assumed to follow Reynolds viscosity model. Rosseland approximation is used to describe the radiative heat flux in the energy equation. The governing equations in their non-similar form are solved numerically by local non-similarity method. The effects of variable viscosity, viscous dissipation, radiation and the power-law index parameters on the velocity and temperature profiles as well as on the heat transfer coefficient are analyzed. © Kairi et al.published_or_final_versio

    Effects of temperature dependent viscosity on BĂ©nard convection in a porous medium using a non-Darcy model

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    Temperature-dependent viscosity variation effect on Benard convection, of a gas or a liquid, in an enclosure filled with a porous medium is studied numerically, based on the general model of momentum transfer in a porous medium. The exponential form of viscosity-temperature relation is applied to examine three cases of viscosity-temperature relation: constant (mu = mu(C)), decreasing (down to 0.13 mu C) and increasing (up to 7.39 mu(C)). Effects of fluid viscosity variation on isotherms, streamlines, and the Nusselt number are studied. Application of the effective and average Rayleigh number is examined. Defining a reference temperature, which does not change with the Rayleigh number but increases with the Darcy number, is found to be a viable option to account for temperature-dependent viscosity variation. (C) 2007 Published by Elsevier Ltd

    Laminar film condensation heat transfer on a vertical, non-isothermal, semi-infinite plate

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    This paper gives similarity transformations for laminar film condensation on a vertical flat plate with variable temperature distribution and finds analytical solutions for arbitrary Prandtl numbers and condensation rates. The work contrasts with Sparrow and Gregg's assertion that wall temperature variation does not permit similarity solutions. To resolve the long debatable issue regarding heat transfer of non-isothermal case, some useful formulas are obtained, including significant correlations for varying Prandtl numbers. Results are compared with the available experimental data

    An approximate solution of the MHD Falkner-Skan flow by Hermite functions pseudospectral method

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    Based on a new approximation method, namely pseudospectral method, a solution for the three order nonlinear ordinary differential laminar boundary layer Falkner-Skan equation has been obtained on the semi-infinite domain. The proposed approach is equipped by the orthogonal Hermite functions that have perfect properties to achieve this goal. This method solves the problem on the semi-infinite domain without truncating it to a finite domain and transforming domain of the problem to a finite domain. In addition, this method reduces solution of the problem to solution of a system of algebraic equations. We also present the comparison of this work with numerical results and show that the present method is applicable.Comment: 15 pages, 4 figures; Published online in the journal of "Communications in Nonlinear Science and Numerical Simulation

    Finite element modeling of free surface flow in variable porosity media

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    The aim of the present work is to present an overview of some numerical procedures for the simulation of free surface flows within a porous structure. A particular algorithm developed by the authors for solving this type of problems is presented. A modified form of the classical Navier–Stokes equations is proposed, with the principal aim of simulating in a unified way the seepage flow inside rockfill-like porous material and the free surface flow in the clear fluid region. The problem is solved using a semi-explicit stabilized fractional step algorithm where velocity is calculated using a 4th order Runge–Kutta scheme. The numerical formulation is developed in an Eulerian framework using a level set technique to track the evolution of the free surface. An edge-based data structure is employed to allow an easy OpenMP parallelization of the resulting finite element code. The numerical model is validated against laboratory experiments on small scale rockfill dams and is compared with other existing methods for solving similar problems.Peer ReviewedPostprint (author’s final draft

    Heat and Mass Transfer On MHD Flow Problems with Hall and Ion Slip Effects On Exponentially Accelerated Plate

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    We in this paper intended to investigate heat and mass transfer for MHD free convective flow for exponentially accelerated plate. The effects of Ion slip and Hall are studied considering variable temperatures, concentration, and angle of inclination. We applied finite element analysis for solving governing equations. Flow velocity, concentration and temperature’s graphical profiles are examined for non-dimensional parameters. Flow reversal is prevented due to magnetic field, is observed. Velocity experiences retarding effect due to angle of inclination, this helps in acknowledging drag force in seepage flow

    Heat and Mass Transfer On MHD Flow Problems with Hall and Ion Slip Effects On Exponentially Accelerated Plate

    Get PDF
    We in this paper intended to investigate heat and mass transfer for MHD free convective flow for exponentially accelerated plate. The effects of Ion slip and Hall are studied considering variable temperatures, concentration, and angle of inclination. We applied finite element analysis for solving governing equations. Flow velocity, concentration and temperature’s graphical profiles are examined for non-dimensional parameters. Flow reversal is prevented due to magnetic field, is observed. Velocity experiences retarding effect due to angle of inclination, this helps in acknowledging drag force in seepage flow
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