Electromagnetic Control of Flow Separation

The flow of electrically conducting fluids like sea water around bodies can be controlled by electromagnetic forces. These forces may be generated by a suitably chosen arrangement of permanent magnets and electrodes on the surface of the body.

We consider surface parallel Lorentz-forces acting in streamwise direction.This configuration allows to prevent the boundary layer from separation, resulting in higher lift and/or lower form drag of the body.Experimental results on the flow around a circular cylinder, an inclined plate and a hydrofoil are presented for Reynolds numbers up to 10**5. In the caseof the cylinder both steady and time-periodic forcing are applied.

The experiments were carried out in an open channel with sodium hydroxide as the working fluid and in a sea water facility. Flow visualizations showing serious separation delays will be presented together with values for drag and lift in different configurations.

Direct numerical simulations at low Reynolds numbers confirm the physical tendencies of the experiments.