Numerical Investigation of Flow Asymmetry Around Slender Body at High Angles of Attack

Abstract

Flow asymmetry around slender body at high angles of attack is investigated numerically. LES of the flow around an Ogive-cylinder body at high angles of attack is carried out. The asymmetric wake-vortex phenomenon was observed at angles of attack of α = 55◦ and α = 65◦. The results showed that the phenomenon is present in the absence of artificial geometrical or flow asymmetry. An investigation of the unsteady flow field was carried out using dynamic mode decomposition. The analysis identified two dominant unsteady modes; unsteady wake and unsteady shear layer. At angle of attack 45◦ the shear mode is dominant upstream and the low-frequency wake mode is dominant downstream. For α = 55◦ the high-frequency shear-layer is dominant downstream of vortex breakdown. At α = 65◦ the spectrum shows a wide range of modes. Further investigations are necessary to understand the relation between mode switching and the initiation of flow asymmetry as the angle of attack is increased.