DOUBLE DIFFUSIVE NATURAL CONVECTION IN OPEN CAVITY UNDER THE SORET AND DUFOUR EFFECTS

Double diffusive natural convection in an open cavity under the Soret and Dufour effect is simulated numerically. The influences of different Rayleigh numbers (range from 103 to 107), Lewis numbers (range from 0.5 to 8), buoyancy ratios (range from -5 to 5) and Soret and Dufour (range from 0 to 0.5) on the flow field, temperature and concentration distributions, as well as on the variation of the average Nusselt number and the average Sherwood number are investigated. The result shows that, when buoyancy ratios is -1, the average Nusselt number and the average Sherwood number reaches the minimum, namely the heat and mass transfer in the cavity are the weakest. The increase of Lewis numbers under a fixed Rayleigh numbers would lead to decreased the average Nusselt number and gradually increased the average Sherwood number. When the value of Rayleigh numbers is small, the change of Lewis numbers has little effect on heat and mass transfer. Both the average Nusselt number and the average Sherwood number increase as Soret and Dufour increase. When Dufour and Soret simultaneously varies from 0.1 to 0.5, compared with some cases, the Soret and Dufour effects are not considered, the average Nusselt number increases by 10.4% to 58.0% and the average Sherwood number increases by 3.4% to 13.1% respectively. In addition, the Soret and Dufour effect on the heat and mass transfer in open cavity is not obvious when Lewis numbers is 1.