Simulation of Flow over Two Unequal Square Cylinders

Abstract

A two dimensional hybrid discrete vortex method is used to simulate flow over two unequal square cylinders in side-by-side arrangements at a Reynolds number Re D = 550. The large cylinder face width is twice that of the small cylinder, giving a ratio of D/d = 2. The normalized transverse spacing of the cylinder centres varied between 0.875 ≤ T/D ≤ 8. Independent vortex streets are observed in the wake of the two unequal square cylinders at T/D = 8. Proximity interference commences at T/D = 4 with interactions between the two vortex streets. The interaction results in a synchronized vortex’shedding at T/D = 2.75. At T/D = 1.25, the gap flow is predominantly biased towards the small cylinder, due to the shear layer interactions in the small cylinder wake. At T/D = 0.875, the gap flow is weak and vortices are shed from the outer sides of the two square cylinders, forming a single vortex street.