Effect of the geometric features of the harbor seal vibrissa based biomimetic cylinder on the flow over a cylinder

The present study numerically investigates the effect of the geometrical features of a harbor seal vibrissa (HSV) on the flow characteristics for the Reynolds number (Re) of 500 by using the large eddy simulation (LES). Seven HSV-like geometries are designed by combining the minor-axis undulation, the major-axis undulation, the bothaxis undulation and the offset angle. The present study aims at providing the idea to design the geometric disturbance for the bluff flow control to realize the reduction of the forces by analyzing the geometric features of the HSV. In addition, the elliptic cylinder was included for the purpose of the comparison. All HSV features present the reduction of the drag coefficient and the suppression of the lift fluctuation, comparing to the elliptic cylinder. The amount of the reduction of the force coefficients depends on the geometric feature. Among the features of the HSV shape, the major-axis undulation was dominant to the modification of the vortical structures and the Strouhal number. Each component of the vorticity differently responded to the features of the HSV geometry. The undulations provided the additional vorticities and the offset angle gave the asymmetric effect on the distribution of the additional vorticities.