Effect of the geometric features of the harbor seal vibrissa based biomimetic cylinder on the forced convection heat transfer

The present study numerically investigates the effect of the geometrical features of a harbor seal vibrissa (HSV) on the forced convection heat transfer 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 both-axis undulation and the offset angle. In addition, the elliptic cylinder was included for the purpose of the comparison. All modified geometries with the HSV features present the reduction of the time-averaged drag coefficient, comparing to the mean drag coefficient of the elliptic cylinder. The geometries containing the major-axis undulation without an offset angle achieve a large amount of the reduction of the mean drag coefficient and the suppression of the lift fluctuation. The minor-axis undulation gives the smallest reduction of the drag coefficient and the lift fluctuation. The both-axis undulation produces the largest reduction rate of the time- and total surface-averaged Nusselt number in comparison with the elliptic cylinder. The undulation of the major-axis gives a larger effect on the spanwise dependence of the mean Nusselt number than that of the minor-axis. The presence of the wake vortices according to the spanwise position depend on the geometric features of the HSV, which associates to the thickness of the thermal boundary layer and eventually the heat transfer. It can be carefully concluded that the major-axis undulation among the geometric features of HSV is a key feature to affect the forced convection heat transfer. (C) 2020 Elsevier Ltd. All rights reserved.