Large Eddy Simulation of the Wake Behind an Ellipsoid at 45° Incidence Angle

For the well-defined bodies of revolution, the viscous flow past Prolate spheroids has fascinated scientists in fluid mechanics, marine hydrodynamics and aero-dynamical communities for decades. Previous experiment in different yaw and pitch angles of a prolate-spheroid like submarine mode suggests that the asymmetry is a feature of the high Reynolds wake of the symmetric body of revolution with incline angle. The objective of this paper is to examine the similar phenomenon — the asymmetric wake flow — in the relatively low Reynolds number. The present paper focuses on flow field with LES model for a 45° inclined 6:1 prolate spheroid. LESs of the flow and wake have been conducted at Reynolds numbers Re_D = 3000, and 10000 (Re_D based on the free-stream velocity U₀ and the minor axes length D). The maximum grid points reaches 30 million. Results from simulation show the dominant structure of the wake to be a pair of counter-rotating vortices. Detailed observations and analyses show strong leeward side axial flow. Simulation results from LES were compared with the DNS results for Re_D = 3000. The wake at Re_D = 3000 and 10000 shown was complex with numerous disordered vortical structures. Strong asymmetric wake and large side-force were surprisingly observed and the asymmetry in near field and far field were analyzed and compared.