The results in this paper arise from an investigation into control strategies designed to trap a vortex in a cavity such that the flow remains attached with no large scale vortex shedding. Progress in this general area is required to advance the development of thick winged aircraft where, for example, such wings could be used to store more fuel. A discrete vortex computational dynamics model of the flow is used to develop simple but effective control strategies. In this paper, the use of constant suction or a PI controller to stabilize the flow, followed by oscillatory open loop suction to maintain stability with a significantly reduced effort is investigated. To support the simulation studies, results from wind tunnel experiments are given.