侧向局部加热腔体内对流时空结构的研究

Spatio-temporal structure of the convection heated locally from side

通过二维流体力学基本方程组的数值模拟,研究了普朗特数Pr=6.949时侧向局部加热腔体内水平温差驱动的自然对流。仔细观察腔体内水平流的入侵过程,发现在冷热流体交接面的上下部位同时出现了冷入侵流和热入侵流,并且在交汇处有破碎扰动波出现。揭示了周期性双局部对流结构,并发现在右壁面温度高于左壁面温度区域顶部有对流卷生成,对流卷随时间沿侧壁面向腔体下部移动,最后消失,同时又有新对流卷在该区域顶部生成,这种现象重复循环着。结果表明:在右壁面温度高于左壁面温度区域,热边界层厚度(θδ)随腔体高度增加而增大;在右壁面温度等于左壁面温度区域,θδ值随腔体高度增加而减小;并且格拉晓夫数(Gr)越大,θδ值越小。

Natural convection of heating locally from side wall is investigated at Prandtl number Pr=6.949 by means of numerical simulation of 2-D equations of hydrodynamics. The invasion process of horizontal-flow is carefully observed, and found that the hot and cold invasion flow appears in the upper and lower of cold and hot fluid interface at the same time, and interchange where it has broken disturbances. This phenomenon has been found through careful observing the process of invasion. The periodic double-local convection structures are revealed. Convection rolls is generated at the right wall temperature higher than left wall temperature zone top and it moved down along left wall with time, and convection rolls finally disappear at this zone bottom. At the same time, the new convection rolls is generated again. This phenomenon cycled. In the zone where the temperature of right wall is higher than the one of the left wall, the thickness of thermal boundary layer increases with cavity height, but in the other zone where the temperature of the right wall is equal to the one of left wall, the thickness of thermal boundary layer decreases with increasing the Grash of number.