Effects of Reynolds Number on Vortex Structure Evolution in a Square Cavity with Two Opposite Moving Lids

Abstract

The vortex structure of two-dimensional flow in a cavity is calculated using the differential quadrature method. The numerical simulation focuses on investigating the effects of Reynolds number on vortex structure evolution of the flow in a square cavity with two opposite and equal speed moving lids. The streamline patterns and bifurcation diagrams are determined. The numerical results show that the flow in the cavity takes on the streamline pattern of completely symmetric vortex structure when the Reynolds number approaches zero. With the Reynolds number increasing, the sizes and center positions of the sub-vortexes appear to be affected, whereas the saddle point is still located at the cavity center, resulting in a skewed flow pattern in the cavity. It is observed that one large vortex occupies the entire cavity and the shape of the large vortex becomes more circular after a critical value of the Reynolds number is exceeded. If the Reynolds number is increased further, two secondary eddies emerge simultaneously on the upper left corner and the lower right corner near the sidewalls. The center of the large vortex is invariably located at the cavity centre. For different Reynolds numbers, the streamline patterns are symmetric about the cavity center which is always a stagnation point.