Hydromagnetic Double-diffusiveConvection In A Porous Medium With Opposing Temperature And Concentration Gradients

• Main Authors: Chia-Lin Tzeng, 曾家麟
• Other Authors: Chung-Jen Tseng
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/12754919237658553592

碩士 === 國立中央大學 === 機械工程研究所 === 92 === The problem of hydromagnetic double-diffusive convective flow of a binary mixture in a porous rectangular enclosure is solved numerically in this work. The effects of viscosity and inertial force of the porous medium are considered. The upper and lower walls are insulated. Constant temperatures and concentrations are imposed along the left and right walls of the porous enclosure and a uniform magnetic field is applied in the x-direction. The buoyancy ratio is in the range of 0.0~2.0, Prandtl number in 1.0~5.0, Lewis number in 0.1~2.0, Rayleigh number in 105~107, Darcy number in 10-5~10-1, porosity in 0.2~0.8 and the enclosure aspect ratio is fixed at 2.0. Results for various conditions were presented and discussed. It is found that the flow structure and heat transfer characteristics inside the enclosure depend strongly on the porosity, permeability, the magnetic field, the effect of buoyancy and the thermal inertia. The effect of the magnetic field is found to reduce the movement of the convection within the enclosure. For the unsteady case, the flow oscillates periodically at high Rayleigh number and high heat capacity ratio. The application of magnetic field reduces the oscillation. Finally, this work provides correlations of the Nusselt number vs. porosity and the Hartmann number.