The mechanics of near wake region of 75 degree triangular cylinder at intermediate Reynolds number

Abstract

The previous researchers observed that vortical structures dominate the near wake region behind triangular cylinders at different Reynolds numbers. On studying the near wake region of 75 degree triangular cylinder at different Reynolds numbers, a system of interdependent vortices was found to exist in the near wake region of the cylinder by the authors. The variation in the vorticity of secondary vortex was observed to be periodic. However, this periodic pattern depends on Reynolds number. It was further observed that at Re = 640 the vorticity followed a specific pattern not observed over other Reynolds numbers. The current study was carried out to mathematically define this observed periodic variation in the vorticity of the secondary vortices at Re = 640. It was identified that the mathematical equations used for modelling the phenomenon of beats are able to explain the relationship between the vorticities of positive and negative secondary vortices. The phenomenon was quantified by calculating the beat parameters such as beat frequency and amplitude in the study. The explanation of the phenomenon by use of beat equations indicates that the vorticity variation frequencies of positive and negative secondary vortices become close to each other at Re = 640.