ABSTRACT
ABSTRACT: Fluid forces acting on a cylinder often characterizes flow configuration on the cylinder. Fluid forces acting on two cylinders in staggered configurations were measured in wind-tunnel test at a Reynolds number of 5.5× 104 and, then magnitudes and trends of fluid force coefficients with change in spacing ratio T/D are discussed in light of flow configurations determined on the basis of time-averaged and fluctuating surface pressure, surface oil-flow patterns, and flow visualization patterns. At all stagger angles of two cylinders with very smaller spacings, lift forces acting on the cylinders are mainly governed by the behavior of flow in the gap between the cylinders, and a series of bistable flow caused by intermittent formation and burst of separation bubble on the upstream cylinder was found.
