Forces on a circular cylinder near a plane wall

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 < G/D < 2, 0.12 < δ/D < 0.97 and 4.8 × 10⁴ Re 3 × 10⁵. 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.