Turbulent drag reduction by Lorentz force oscillation

An experimental investigation into an electromagnetic technique to reduce skin-friction drag of turbulent boundary layers was conducted with an electroconductive solution in water, with potential applications to ships and underwater vehicles. We used an array of actuators made of permanent magnets interleaved with copper electrodes, which are set flush with the wall surface across the flow. This setup created the Lorentz force in the cross-flow direction within a thin region near the wall. More than 40% of turbulent skin-friction reductions were observed when the electromagnetic force is oscillated across the flow. (C) 2004 American Institute of Physics.