Analysis of the entropy generation in a nanofluid-filled cavity in the presence of magnetic field and uniform heat generation/absorption

摘要

This paper examines the natural convection in a square enclosure filled with awater-Al_2O_3 nanofluid in the presence of magnetic field and uniformheat generation/absorption. The left wall is hot, the right wall is cold and the horizontalwalls are insulated. Lattice Boltzmannmethod (LBM) is applied to solve the coupled equations of flow and temperature fields. The entropy generation due to heat transfer, fluid friction and magnetic effect has been determined by the finite difference method. This study has been carried out for the pertinent parameters in the following ranges: Rayleigh number of the base fluid, Ra= 10~3 to 10~6, Hartmann number varied from Ha= 0 to 60, heat generation/absorption coefficient q = -10 to 10 and the solid volume fraction of nanoparticles between ф=0 and 6%. For Ra≤10~5 and Ha≤30, the results showthat the heat generation/absorption coefficient influences heat transfer rate, but it does not affect the entropy generation in the range -10 b q b 5. Also it is observed that adding nanoparticle reduces the entropy generation. The nanoparticle effect is more intense for high Hartmann number.