多孔介质方腔内混合对流格子Boltzmann模拟

采用格子Boltzmann方法，对多孔介质方腔内的混合对流现象进行研究.方腔内部中心有一发热圆，径宽比D/L=0.4，冷流体从方腔左下角入口流进，从方腔左上角出口流出，四周壁面绝热.在普朗特数Pr=0.71和格拉晓夫数Gr=1.4×10⁴时，分析理查德森数Ri和达西数Da对发热圆表面平均努赛尔数Nu的影响.结果表明：Ri数位于10^-3~10范围内，Nu随Ri的增大而减小.Da越大，Ri对Nu的影响越显著；Da数位于10^-5~10^-2范围内，强制对流占主导的情况下（Ri≤0.1），Nu随着多孔介质的Da的增大而增大.自然对流占主导的情况下（Ri=10），Nu对Da的变化不敏感.

Lattice Boltzmann Simulation of Mixed Convection in an Enclosure Filled with Porous Medium

Lattice Boltzmann method is adopted to investigate mixed convection in an enclosure filled with porous medium.A heated cylinder (D/L=0.4) is located at center of the enclosure with high temperature.Inlet flow with low temperature is located at lower-left wall of the enclosure and exit is at upper-left wall.Other walls are assumed adiabatic.Influences of Richardson number Ri and Darcy number Da on average Nusselt number Nu around heated cylinder are investigated while Prandtl and Grashof numbers are kept at 0.71 and 1.4×10⁴, respectively.It indicates that Nu decreases with increasing Ri.Influence of Richardson number on Nu is significant as Darcy number is great.At 10^-5≤Da≤10^-2, Nu increases with increasing Darcy number as forced convection dominates flow (Ri≤0.1).As natural convection dominates flow (Ri=10), Nu is not sensitive to Darcy number.