Khomenko O. Flow control in hydrodynamic systems based on the properties of trapped vortices

The method of nonlinear control of the wall flow in cylindrical grooves is proposed. The method differs by using the modified trapped vortex model and provides the necessary requirements for the formation of the flow structure. New properties of the trapped vortex near the surface irregularities and in the presence of the flow perturbations are studied. The nonlinear controller of the wall flow, which differs in that it takes into account the equation of equilibrium of the caught vortex and the unseparated flow condition in the groove edges and provides active feedback control in a non-stationary flow is developed. The developed controller is used to calculate the parameters of an active control circuit with feedback in a non-stationary flow, when the system responds to external perturbation. The problem of reducing the hydrodynamic loads of a square cylinder is solved on via the modified model of the trapped vortex. The control parameters of a square cylinder with frontal plates which reduce the hydrodynamic load are found. In order to estimate an efficiency of the control scheme, numerical simulation of viscous flow around the cylinder with frontal plates was carried out in the range of moderate Reynolds numbers. The results of the work show that it is essential to take the flow topology into account when developing new algorithms for flow control near bluff bodies.