Scaling parameters for a time-averaged separation bubble.

A splitter is placed in the wake of a two-dimensional bluff body. The splitter plate is long enough for the separated flow behind the body to reattach on the splitter plate. The time-averaged properties of this 'closed' separation bubble are investigated under a wide range of kinematic conditions. It is found that blockage reduces the base pressure coefficient (C SUB p SUB b) and the distance to reattachment (l) but the relationship between l and C SUB p SUB b is not obvious. The pressure distribution in the separated zone, scaled on C SUB p SUB b and l, can be described by a universal curve. The usefulness of a slotted wall in reducing blockage effects on bluff body flows is shown to be limited in that the wall porosity affects only some properties of the separation bubble. (A)