Hysteresis of Flow Around an Elliptic Cylinder in Critical Reynolds Number Regime

Experimental investigations of the flow around an elliptic cylinder of axis ratio 1:2 were carried out for several angles of attack in a wide range of Reynolds number. The flow characteristics were studied by measuring the fluid forces and the surface pressure. In the critical Reynolds number regime, a discontinuous change of flow state was observed. This change was accompanied by the remarkable hysteresis phenomenon. The fluctuation of fluid forces and surface pressure, in general, markedly decreases in the critical flow state.