CFD Analysis of Vortex Shedding Behaviour Over Different Geometries

In order to investigate the vortex shedding characteristics of subcritical air flow over a variety of two-dimensional bluff body models, CFD analysis was conducted. In the subcritical regime, flow was simulated for four distinct Reynolds numbers: 45, 250, 800, and 1435 on a circle and a square model both having a hydraulic diameter of 5 mm. In order to examine the flow pattern, shedding nature, and acoustic properties, simulations of both the steady state and transient circumstances were performed. For the Reynolds number of 45, the maximum drag coefficient was demonstrated by both models. Up to a Reynolds number of 250, the drag coefficient drops monotonically, after that it practically stays constant throughout the remaining Reynolds number range. When the Reynolds number is lower (Re = 45), there is no vortex shedding at all for the given two models. Additionally, given the same Reynolds number, the circular geometry with a Strouhal number of 0.175 exhibits the highest shedding frequency. However, for the square model, the Strouhal number reaches its maximum at a slightly higher Reynolds number (Re = 250). The Strouhal number then decreases while Reynolds number continues to rise. The outcome demonstrates that early flow separation induces multiple flow separation sites over the models, which forces a decline in the shedding frequency magnitude.