Steady flow past a circular cylinder under large blockage

Abstract

The flow past a circular cylinder constrained under large blockage exhibits features even in the steady regime, that strikingly contrast those corresponding to its unbounded counterpart. While several studies are dedicated towards understanding this classical flow problem in unbounded medium, surprisingly, very little efforts have been put forward to extract details of flow alterations in a highly confined flow. The absence of flow solutions and comprehensive data acts as an impetus behind the current work that computes steady, two-dimensional flow over the Reynolds number, Re range of 4–100 under a large blockage of 0.9. The imposition of large blockage stabilizes the flow; it enhances the Re limit of fore-aft flow symmetry to 5, delays the onset of laminar separation to Re=27.8 and preserves the steady nature of flow even at Re=100. The wake grows non-linearly with Re. For Re≤5, the base pressure represents the minimum surface pressure and eliminates any development of adverse pressure gradient along the cylinder. The order of magnitude rise in the drag and drop of surface pressure are overwhelming. There exists a competition of pressure gradient on the sidewalls and cylinder surface for 6≤Re<15.