Steady laminar flow past a slotted circular cylinder

A numerical study of the viscous flow past a slotted circular cylinder is presented for the low Reynolds number (Re) regime. The computations are carried out for Re varying from 10 to 50 since it is observed that the flow separation causes the bubble formation at Re > 7 and its shedding at Re > 47 for the slotted cylinder. The solid circular cylinder is modified with three different shapes of slit (converging, diverging, and parallel) of width 0.1 times diameter (0.1D) of the circular cylinder located symmetric to its horizontal axis. Analysis is carried out to understand the flow pattern and effect of slit shapes on the bubble formation, flow separation, and drag coefficient at low Re. It is observed that the size of the bubble increases with an increase in Re and attains the highest value for the cylinder with no slit. The drag coefficient decreases with an increase in the Reynolds number, but it is highly influenced by the viscous effect imparted by the slits. Having a minimum value of pressure drag for the slotted cylinders compared to the normal cylinder, the total drag is found to be maximum due to the dominance of the viscous drag.