Forces on a circular cylinder near a plane wall

Abstract The drag and lift force are measured on circular cylinders fitted with end plates in a wind tunnel. The gap between the cylinder and the wall, G, the thickness of the turbulent boundary layer along the wall, δ, and the Reynolds number, Re , are varied in the following ranges: 0 4 ⩽ Re ⩽ 3 × 10 5 . The lift and drag coefficients are presented in terms of a new variable G/δ. It is found that the lift coefficient is governed by the gap to diameter ratio G/D while the drag coefficient is dominated by the ratio of gap to thickness of the boundary layer, G/δ.