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This numerical study deals with heat convection in a porous media. The heat transfer is modeled using Darcy-Brinkman-Forcheimer formulation. A CFD code based on the finite volume method is used to solve the mathematical set of equations governing air flow and convective heat transfer in the porous media. The numerical predictions are validated by comparison with results available in the literature. Parameters governing heat transfer and fluid flow are investigated (Rayleigh number, Darcy number and porosity). Increasing Rayleigh and Darcy numbers resulted in enhancing the heat transfer rate but the convective heat transfer rate decreased with increasing porosity.

A numerical study of the mixed convection of liquid metal in Czochralski configuration for crystal growth was carried out. The finite volume method with SIMPLER Algorithm was used to solve the conservation equations of mass, momentum and energy. Due to computational constraints, the simulations were limited to axisymmetric geometries. The obtained results are compared to the experimental data of the literature. The effect of Richardson number on the flow structure and the thermal field has been presented and discussed for Ri = 0.1, 0.5, 1, 1.5 and 2. The effect of the aspect ratio of the cavity was also analysed. The results showed that increasing of Richardson number increases the velocity of the fluid in the cavity and reduces the rate of heat transfer. The aspect ratio had a significant effect on the velocity and thermal fields.

Flow convection in agriculture greenhouse is one of the most important factors on the growth and fruiting of plants. The present work focused on natural convection in an open greenhouse heated by ridge tubes in presence of plants. Analyses are performed for different boundary conditions imposed at the roof such as constant temperature, convective heat flux, and convective and radiative heat flux. The governing equations comprising continuity, momentum and energy equations are solved by Ansys-Fluent software. In each case, the average velocity and temperature of the air are determined. The obtained results are presented in terms velocity and temperature profiles. Isothermal lines and velocity vectors showed that by increasing the convective heat transfer coefficient, the average temperature and average airflow velocity decrease. The outcomes of this study help build greenhouses with dimensions and materials to suitable for the given external conditions.

A numerical study of the transition from steady to oscillatory flow natural convection of low-Prandtl number fluids inside the 3D Bridgman configuration has been carried out. The three-dimensional Navier-Stokes and energy equations, with the Boussinesq approximation have been discretized by means of a finite volume procedure which employs a second order accurate central difference scheme to treat diffusive and convective fluxes. In natural convection, the buoyancy force is only driving the flow and its intensity can be move a harmful effect on the crystal growth, such as the striation. Naturally, the steady state flow is obtained for low Rayleigh number and shows a great dependence between the Rayleigh number, the flow structure and the heat transfer rate. A low increase in the Rayleigh number we guide to determine the critical point in which the 3D flow became oscillatory. This regime appears by a sinusoidal signal in the time and developed in each period of time.