Effect of height ratio on wake transition in unsteady flow past isosceles trapezoidal cylinder

Two-dimensional numerical investigations are carried out on flow past a trapezoidal cylinder confined in a channel by using an indigenously developed finite difference-based flow solver. The solver uses body-fitting coordinate transformation and the marker and cell (MAC) algorithm. Laminar flow of air has been considered past the cylinder of varying height ratio (HR) from 0.2 to 1.0 over a range of Reynolds numbers (Re) from 60 to 200. Effects of HR and Re have been studied on wake and dynamic characteristics for two different orientations of the isosceles trapezoidal cylinder, viz., base facing and apex facing. Critical value of Re for onset of vortex shedding has been identified for both the configurations. Results from the present work illustrate how separation behavior gets modified with change in Re and HR. Also the work aims to find such values of HR that are associated with minimum drag and cause maximum delay in the onset of vortex shedding.