Numerical analysis of control of flow oscillations in open cavity using moving bottom wall

Abstract

In this study, we investigate the active control of self-sustained oscillating flow over an open cavity using a moving bottom wall. The incompressible Navier-Stokes equations are solved using finite difference methods for the two-dimensional cavity with laminar boundary layer upstream. We move the cavity bottom wall tangentially with nondimensional velocities ranging from -0.2 to +0.2. The results show that wall velocity changes the characteristics of recirculating flow in the cavity and that the modification of recirculating flow plays an important role in changing the oscillation characteristics of the separated shear layer. When the wall velocity is less than -0.1, two recirculating vortices change to one clockwise recirculating vortex in the cavity, so that the self-excited shear layer oscillations are completely suppressed. When the wall velocity is more than +0.19, two stationary vortices exist on the upper side and lower side of the cavity and the self-excited shear layer oscillations are suppressed.