【摘要】 通过数值模拟 ,研究了温度和浓度梯度为水平方向、内壁和外壁上的温度和浓度保持定值的竖直环形容器内的双扩散对流结构 ,其中浮升力之比N =GrS GrT=- 1 ,GrS 和GrT 分别为溶质格拉晓夫数和热格拉晓夫数 .首先对环形容器与矩形容器内的双扩散对流状况进行了比较 ;然后着重分析了在双扩散对流情况下竖直环形容器内壁面处的热 (溶质 )边界层以及平均传热 (质 )率Nu(Sh)随Le数的变化情况 .结果表明 ,溶质边界层的厚度随着Le数的增大逐渐减小 ,而热边界层随Le数的变化不大 ;与Sh数一直随Le数的增大呈明显的上升趋势不同 ,当Le>1 0后Nu数随Le数的变化趋于平缓更多还原

【Abstract】 A numerical study is presented of the structure of double diffusive co nvection in an annual cavity with horizontal heat and mass gradients due to cons tant temperatures and concentrations along the vertical side-walls, respectivel y . The buoyancy ratio N=Gr S/Gr T is equal to -1, where Gr S and Gr T are the solutal and thermal Grashof numbers, respectively. The structures of double diffusive c onvection in rectangular and annular cavity were compared. Numerical results are reported for the effect of the Le numbers on the thermal (solute) boundary laye r and the average rate of heat (mass) transfer Nu(Sh). The results show that th e thickness of solutal boundary layer decreases when the Lewis Number increases, but the thermal boundary is not significantly influenced when the Lewis number varies; contrasting with the steady increase of the Sherwood number, the Nus selt number varies slowly when the Lewis number is higher than 10.更多还原