Large eddy simulation of flow over square cylinders with sharp and chamfered corners

Abstract

For the sharp cylinder case, LES predictions including forces, Strouhal number, surface pressure coefficient and velocity profiles are compared against experimental datasets as well as previous LES and direct numerical simulation (DNS) results. We observe a good agreement between the current LES data and other datasets. Subsequently, LES predictions for the chamfered cylinder case are compared against that of the sharp cylinder case. There are some similarities in the characteristics of the flowfields, surface pressure coefficient and velocity profiles between the two cases. However, the wake dynamics are significantly different between the two cases while the mean and fluctuating forces are remarkably smaller for the chamfered cylinder case.

In this study, large eddy simulations (LES) of flow over two square cylinders are performed to study vortex shedding and wake dynamics. In one case the square cylinder has sharp corners while in the other case it has chamfered corners. In both cases, the angle of attack is 0$^\circ$ and Reynolds number is 60,000.

Many applications in science and engineering encounter complex turbulent flow around bluff bodies such as flow around a landing gear of an aircraft or around a tall building. In such flows, an accurate understanding of the flow physics associated with vortex shedding and wake dynamics behind bluff bodies is essential for scientists and engineers. For example, vortex shedding can cause large fluctuating aerodynamic loads that are imparted to the body or structure and can in-turn cause undesirable consequences such as structural fatigue and failure. In particular, consider the case of tall buildings or skyscrapers that are being built more and more all around the world due to urbanization and rapid increase in the world population. Unlike a short building, the aerodynamic aspect in the design of a tall building is much more crucial to investigate and quantify for the safety of the building. Furthermore, in tall buildings, the use of corner modifications to alter or reduce the unsteady aerodynamic loading on the buildings is becoming more common.