Numerical study on the flow around an elliptic cylinder with different aspect ratios in the subcritical regime using large eddy simulation

Abstract

The aerodynamic characteristics, flow fields, and flow patterns of the flow around an elliptic cylinder are investigated in this paper using large eddy simulation (LES). The Reynolds number (Re) is fixed at 16 000 in the subcritical regime, and the aspect ratio (AR) of the elliptic cylinder is varied from 0.6 to 1.4 with an increment of 0.2. The numerical model applied is initially validated for the case of AR = 1, showing good agreement with previous studies. The numerical results indicate that both the mean drag coefficient and the root mean square of lift coefficient of the elliptic cylinder decrease with increasing AR. The total drag is decomposed into two components: it indicates that the pressure drag is dominant. The primary separation point of the elliptic cylinder shifts backward with increasing AR within the range of 86.4°–92.3°. The flow fields are analyzed in detail through the time-averaged velocity profiles along three different axes. Additionally, the two-dimensional (2D) and three-dimensional (3D) visualizations of the wake patterns are also provided to show the different vortex shedding mode and the characteristics of vortex structure for different ARs. This study supplements the basic aerodynamic parameters and details of the flow around an elliptic cylinder and discusses the influence of AR at a moderate Re in the subcritical regime and has a certain significance for further optimization of the simplified model of the human body for efficient aerodynamic testing of sport garments.