Flow About a Circular Cylinder in and Near a Turbulent Plane Mixing Layer

This paper deals with an experimental study of the fluid forces, surface pressure, and vortex-shedding frequency of a circular cylinder placed in and near a turbulent plane mixing layer with zero velocity ratio. These characteristics are given as functions of the cylinder diameter d divided by the local mixing-layer width δ and the nondimensional transverse coordinate of the center of the cylinder in a Reynolds number range 5500–46000. For the cylinder d/δ = 2.2–2.3 the r.m.s. lift attained a maximum 40 percent higher than that in the uniform flow when a part of the cylinder surface was near an intermittently turbulent edge on the high-velocity side of the mixing layer; the time-mean resultant force attained a sharp maximum as high as 80 percent of that in the uniform flow when the axis of the cylinder was located at the center of the mixing layer. The former maximum was interpreted in terms of a vortex-body interaction while the latter maximum was found to be associated with a large delay of the boundary-layer separation on the low-velocity side of the cylinder.