Rachid Bennacer

Simulation of heat transfer and fluid flow in 3D porous media in non-equilibrium

A study of the laminar free convection in a cubic cavity 3D partially porous media is conducted numerically. The Brinkman-Darcy model with the Boussinesq approximation is used to characterize the flow field inside the porous region, while the local thermal non-equilibrium (LTNE) model are employed for energy equations. A numerical methodology based on the finite volume method and a full multigrid technique is employed. The effects of various parameters; the thermal conductivity ratio (y) and the thickness of the porous layer (e) on the flow patterns are analyzed. The numerical outcome of the present study shows that, the non-equilibrium (LTNE) model and the thickness of porous layer (e) modifiers substantially the flow characteristics and the transfers thermal.

Natural Convection in a Horizontal Cavity Partially Occupied by a Porous Media Saturated by a Coolant Liquid

The natural convection is studied in a cavity witch the lower half is filled with a porous media that is saturated with a first fluid (liquid), and the upper is filled with a second fluid (gas). The horizontal borders are heated and cooled by uniform heat fluxes and vertical ones are adiabatic. The formulation of the problem is based on the Darcy-Brinkman model. The density variation is taken into account by the Boussinesq approximation. The system of the coupled equations is resolved by the classic finite volume method. The numerical results show that the variation of the conductivity of the porous media influences strongly the flow structure and the heat transfer as well as in upper that in the lower zones. The effect of conductivity is conditioned by the porosity which plays a very significant roll on the heat transfer. The structures of this flow show that this kind of problem with specific boundary conditions generates a complex flow structure of several contra-rotating two to two cells, in the upper half of the cavity.Copyright

Heating flux effects on floating zone growth under micro-gravity conditions

Numerical computation of the heat flux distribution effect on the unsteadiness of the liquid bridge flow in mg environment is achieved in a 2D axisymmetrical configuration. A model coupling liquid bridge to phase change is developed. The interaction of the thermo-capillary flows with solid/liquid interface is analysed considering the latent heat effects. The results show the strong effect of external thermal boundary conditions as a control parameter on the hydrodynamic and the crystal grown by using a Floating Zone (FZ) technique. The growth speed is controlled by the latent heat at the interface and the focalisation of the heat flux at the free surface.