方腔热对流大规模数值模拟及其软硬湍流特性

Massive numerical simulation and the characteristics of soft and hard turbulence in 2-D Rayleigh-Bénard thermal convection

该文对二维Rayleigh-Bénard(RB)热对流进行了大规模并行DNS模拟计算。计算中采用了上海超级计算机中心的1024个节点,获得了Pr?0.7,Ra?5×107―8×1011范围内一系列的计算数据和结果。研究结果发现:在二维RB热对流中存在不同的流态,当Ra小于6×108的流动状态为软湍流状态,Ra大于6×108为硬湍流状态;在软湍流状态大尺度环流(LSC)和角区旋涡保持相对稳定,LSC内涡量很小,在硬湍流状态,角区旋涡从边界层内脱落,进入到LSC中随之一起运动,且在LSC内存在大量的小涡旋;并且软湍流和硬湍流在传热效率上具有不同的标度率。

Massive parallel direct numerical simulation （DNS） of two-dimensional （2-D） Rayleigh-B6nard （RB） convection is studied. A series of results spanned the range of 5×10^7 -〈 Ra 〈 8×10^11 and Pr = 0.7 are obtained using 1024 computational nodes at Shanghai Supercomputer Center （SSC）. It is found that there are different flow patterns in 2-D RB thermal convection. The flow is soft turbulence when Ra less than 6×10^8. When Ra greater than 6×1^08, the flow becomes hard turbulence. The large-scale circulation （LSC） and the comer vortices are stable in soft turbulence. The vorticity of LSC is small. In hard turbulence, the comer vortices detach from the boundary layer, go into LSC and move along with it. There are a lot of small vortices in LSC. The scaling laws of heat transport in the two flow patterns are different.