Flow around a sphere in a plane turbulent boundary layer

The flow around a sphere placed at various heights above a plane boundary has been investigated. The diameter of the sphere d was 57 mm, and the Reynolds number based on d was 8.3×104. The gap between the sphere and the plane varied from 0 to 30 mm. The thickness of the turbulent boundary layer at which the sphere was placed varied from 26 to 120 mm. The flow was visualized by the smoke-wire method and the surface oil-flow pattern method. Behaviors of the flow and vortices were observed during flow visualization. The surface pressure distributions on the sphere and the plane were measured, and the drag and lift coefficients were determined by integrating the surface pressure of the sphere. The drag and lift coefficients of the sphere are defined as empirical equations using dimensionless quantities.