An Experimental Study on Flow Past an Equilateral Triangular Prism at Intermediate Reynolds Number and the Effect of its Orientation

Abstract

This paper explores the effect of two orientations (0° and 180°) on near wake region of an equilateral triangular prism at intermediate Reynolds number. The paper also investigates the effect of Reynolds number on the near wake region at intermediate regime. Two orientations are defined such that the apex of the equilateral triangle is pointing upstream and downstream respectively. The flow field behind a triangular prism is different in these two orientations. When apex angle points upstream it corresponds to a fore-body attached to a flat plate while when apex angle points downstream the flat face acts like a flat plate with an after body attached to it. This after-body penetrates the recirculation zone formed behind the flat plate. These two effects are investigated for various Reynolds numbers in intermediate regime. Factors affecting drag coefficient and Strouhal number are different in both cases. In first case the fore-body changes the flow before it gets separated in two free shear layers. In other words, the fore-body affects the free shear layers formed and hence the drag. In the second case, the two shear layers are formed first then their interaction is modified by the after-body in the near wake region behind the prism. Particle Image Velocimetry (PIV) and Hotwire anemometry is being used in present study. Detailed flow field is investigated in terms of velocity magnitude, stream traces, vorticity contours, centerline recovery, power spectra, velocity profiles, Strouhal number and drag coefficient.