Flow Characterization of Bluff Bodies: A Two-Dimensional Transformation From Square to Triangular Cylinder

Abstract

In this study, two-dimensional unsteady, incompressible flow around a square body that is being transformed into a vertex oriented toward the flow configuration of a triangular body is numerically investigated at Re =100 using ANSYS FLUENT 19.0 software. The purpose is to explore the effect of this transformation on the wake characteristics of a square body with l/d = 1 to a triangular body with l/d = 0; where l is the length of lateral and front surface and d is the body height. The effect on the flow behavior caused by the leading-edge transformation from the prospect of wake width, recirculation length, and stagnation pressure difference is discussed. It is seen that as the l/d ratio decreases, the vortex strength increases, which is attributed to the higher stagnation pressure difference value resulting in more intense rolling of the shedding vortex and a smaller wake width. For lower l/d, the fluid traverses a longer distance along the lateral surfaces resulting in greater loss of momentum and hence the lower vortex formation length. The mean drag coefficient is found to be minimum for l/d = 0.75 with stagnation pressure difference and recirculation length being the more dominating factor on this variation. The flow in all the cases separates at the rear surface and the general trend of decrease in drag coefficient with decrease in wake width is not followed. However, such modification leads to better aerodynamic outcome by weakening the periodic drag and lift forces.