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Research describes the macroscopic pressure gradient and interfacial heat transfer coefficient for the analysis of fluid flow and thermal non-equilibrium heat transfer within an anisotropic porous medium. Data indicate that the directional interfacial heat transfer coefficient is analogous to that of the directional permeability.

The hydrodynamic characteristics of a buoyancy-driven convection loop containing an electrically-conducting fluid in a transverse magnetic field are investigated analytically using a one-dimensional model. One side of the loop is isothermally heated and the other side isothermally cooled, and the upper and lower sections are insulated. The model which is based on the use of the Hartmann Plane-Poiseuille flow solution for estimating loop shear stress, predicts the flow velocity and the induced current of the magnetohydrodynamic generator in terms of the flow and geometric parameters. The study covers ranges of Grashof number, Gr, from [10.sup.2] to [10.sup.6], the Hartmann number, Ha, from 0 to 20, the Prandtl number, Pr, from .003 to 7, and loop height to thickness ratio, L/d, from 10 to 50. It is shown that at low Prandtl numbers, Pr [much less than] 1, there exists an optimal Hartmann number, [Ha.sub.opt], that maximizes the induced electric current. This [Ha.sub.opt] depends weakly on the Grashof number. The side-heated loop performance is also compared with the bottom heated loop model of Ghaddar, (1997a). It is found that at a low Prandtl number, side heated loop induces the higher velocity whereas at high Prandtl numbers the bottom heated loop induces higher velocity.

Velocity and temperature profiles for buoyancy-opposing, laminar, mixed-convection flow over a vertical backward-facing step are measured. When the flow is laminar all through the test section, the recirculation region length increases with an increase in the buoyancy force. But, the trend reverses when turbulent flow occurs downstream of the recirculation region. The local Nusselt number in buoyancy-opposing flow is less when the buoyancy force is high.

An enclosure with a porous layer containing a fluid and existing below a fluid layer, is found in a three-dimensional, laminar natural convection. The fluid flow in the porous region is monitored with the Brinkman-extended Darcy formulation. The alternative walls are heated and cooled but the others remain adiabatic. The conservation of mass is assured by the vorticity-vector potential formulation. The convection current in the fluid layer is intensified by the influence of thermal transfer from the porous to the fluid areas.

Transient free convection solutions associated with four kinds of vertical concentric annuli thermal boundary requirements have been obtained in closed form. The solutions include Brinkman and Darcian effects and are suitable to obtain numerical solutions of practical conditions. The procedures to obtain the solutions are discussed.

Byline: Asterios Pantokratoras We study the steady laminar flow along an isothermal vertical impermeable and permeable plate embedded in a saturated porous medium for which the Darcy law is valid. The investigation concerns air and water taking into account the variation of their physical properties with temperature in both upward and downward flow. The results are obtained with the direct numerical solution of the governing equations and cover relatively large temperature differences. The Prandtl number varied between 0.54 and 0.86 for air and between 3.83 and 13.18 for water. It is found that the variation of physical properties with temperature play an important role on wall heat transfer and wall shear stress and large departures from the constant properties values are observed. The largest differences of wall heat transfer and wall shear stress from the corresponding constant properties values reach 75% and 357% in air and 42% and 388% in water.