Resolution of the Turbulent Structure and Resultant Forcing on Thin Cylinders at Zero and Low Angles of Incidence

摘要

Long thin cylinders are commonplace within the US Navy design communities. Their length can support a wide acoustic aperture while currently avoiding the undesirable convective energy by placing large axial gaps between successive hydrophones. Typically, these cylinders experience very thick turbulent boundary layers (TBL) and large Reynolds numbers at both zero and small angles of incidence (AOI). In this paper, we present resolution of the near-wall TBL structure and surface forcing under those flow conditions by large-eddy simulation. The cylinder transverse curvature is clearly the dominant effect on the turbulent structure when compared to the flat plate flow. Simple expressions were derived that predict the tangential surface stress on the cylinder in terms of the radius-based Reynolds number. Conclusively, the flow characteristics of the TBL change dramatically with increasing AOI. The tangential surface stress responds to the dramatic change in the TBL characteristics when the slender cylinder is only slightly inclined to the freestream.