方腔双壁反向驱动流涡结构演化的数值模拟

Numerical Simulation of Vortex Structure Evolution in a Square Cavity with Two Opposite Moving Walls

采用微分求积法计算分析了不同雷诺数的二维方腔驱动流涡结构特性。数值模拟着重研究了雷诺数从0.01到1000变化对方腔双壁反向驱动流涡结构演化的影响,给出了涡演化过程的流型图和分叉图。结果表明,当雷诺数接近0时,腔内流动呈现对称的涡结构流型;随着雷诺数增加,子涡的大小和中心位置发生变化,鞍点始终位于方腔的中心,腔内流动形成非对称的斜扭流型;当雷诺数增大到某一临界值后,单一大涡占住整个方腔,大涡的形状变得更圆;如果雷诺数继续增加,方腔左上角和右下角同时出现二级涡,大涡中心始终位于方腔中心不变。

The vortex structure of two dimensional square cavity driven flow at different Reynolds number was calculated by using differential quadrature method. The numerical simulation focuses on investigating the effects of Reynolds number ranging from 0. 01 to 1000 on vortex structure evolution of the flow in a square cavity with two opposite moving walls. The flow patterns and bifurcation diagrams were determined. The numerical results show that the flow in the cavity takes on the flow pattern of symmetric vortex structure when Reynolds number approaches O. With Reynolds number increasing, the sizes and center positions of the sub-eddies appear to be affected, whereas the saddle point is still located at the cavity centre, resulting in an asymmetric skewed flow pattern in the cavity. It observes that one large vortex occupies the entire cavity; the shape of the large vortex becomes more circular after a critical value of Reynolds number is exceeded. If Reynolds number is increased further, two secondary eddies emerge simultaneously on the upper left corner and the lower right corner. The centre of the large vortex is invariably located at the cavity centre.