STEADY-STATE PRESSURE AND FORCE COEFFICIENTS FOR GROUPS OF 3 EQUISPACED SQUARE CYLINDERS SITUATED IN A CROSS FLOW

The pressure distribution around a square cylinder in a group of three, placed transversely to, and in line with, the free stream direction, have been determined at a flow Reynolds number of 3 x 10(4). The measurements were carried out for spacing ratios in the range 0.1 < S/W < 2, and from these pressure distributions the lift and drag coefficients for the individual cylinders have been determined. These results show that for the transverse configuration large changes in the drag coefficient can occur on any cylinder comprising the group for a relatively small change in cylinder spacing, and that the lift coefficient also exhibits similar characteristics. In a tandem configuration the drag coefficient is negative for downstream cylinders, in the range 0.1 < S/W < 1, after which it becomes positive, but is still strongly influenced by the upstream wake.