CHARACTERIZATION OF A LORENTZ FORCE ACTUATOR

To develop a detailed understanding of the effect of a Lorentz force actuator in sea water, both experiments and numerical simulations of an isolated actuator with no mean flow are conducted. The Lorentz force actuator, comprised of a pair of magnets and a pair of electrodes that produce a volumetric body force, is placed in a vessel containing a uniform water/electrolyte solution. Particle image velocimetry and laser-sheet flow visualization are used to illustrate the induced flow at different orientations of the laser sheet. Simulations are also performed in a static water/electrolyte solution with the same actuator geometry and current levels as the experiments. Comparison between simulation and experiment is remarkably good. Both the simulations and the experiments show that the Lorentz force actuator creates a complex three-dimensional flow over the actuator. Two opposing wall jets are produced by the forces over the electrodes and impinge at the center of the actuator, pushing fluid away from the wall. The curl of the Lorentz force, which acts as a vorticity source, is characterized and the shapes and sizes of the sources of each of the three components are presented.