Document Type


Publication Date





Todd Johnson


Magnetohydrodynamics (MHD) is the behavior of conducting fluids in electric and magnetic fields. Plasmas, liquid metals, and water are all examples of a conducting fluid with magnetic properties. Much of MHD is fluid-flow and the effects of electromagnetic fields on them, but propulsion is also a possibility. A magnetohydrodynamic salt water propulsion system was constructed to observe the effects of salinity on resistivity, and then on the overall efficiency of the drive. Salinity of water and corresponding resistivity was altered to optimize fluid velocity. The apparatus used was a rectangular tube with permanent magnets perpendicular to aluminum electrodes. The fluid acts as a conductor for the Lorentz force, effectively creating an underwater drive without moving parts. In a static no-flow setup, a pressure differential on the order of 10 Pascals was measured. In steady-state free flow, fluid flow of approximately 1 meter per second was observed.

Included in

Physics Commons