Bi-stable flow associated with two tandem unequal diameter cylinders

Abstract

It was found that just like the case of flow past two tandem cylinders of equal diameter, a bi-stable flow situation where the flow switches intermittently between the reattached type and the co-shedding type also exists when the two tandem cylinders have different diameters. The diameter ratio of the cylinders used in the present investigation is 0.33 with the smaller cylinder upstream. It was also found that when the flow is bi-stable, the probability that the flow is of the co-shedding type Pr varies with the centre to centre spacing between the cylinders l/d2 from 0 to 1 over the bi-stable range and their relation is governed by a normal distribution. The range of the bi-stable flow in l/d2 is Reynolds number dependent. When Reynolds number increases, both the lower and upper limits of the bi-stable flow range reduce.