Abstract: The flow of weak electrolyte solution can be controlled by Lorentz force generated by the suitably-chosen electromagnetic field. Lorentz force can be used to suppress the vortex shedding and eliminate the vortex street in the flow around a bluff body for the suppression of vortex-induced vibration (VIV). To investigate the evolutions of VIV suppression by Lorentz force, an exponential polar coordinate system is set up on a moving cylinder, and the stream function-vorticity equations considering the Lorentz force and its initial/boundary conditions, an expression of hydrodynamic force on the cylinder surface as well as the cylinder response equations are then derived. The whole evolutions of cylinder from resting and then undergoing development and suppression due to Lorentz force are calculated and discussed. The development process of cylinder vibration, vortexes shedding and energy transfer, and the deformation and shift of drag-lift phase diagram are described. The results show that the reason of cylinder oscillation is the periodic vibration of lift which is induced by wake vortexes due to flow separation. The fluid flow near boundary layer is changed and the flow separation is suppressed by the Lorentz force on the surface of cylinder so that the flow field tends to symmetry and the periodic vibration of lift is suppressed. The cylinder oscillation can be suppressed and even eliminated for a large value of Lorentz force.

Key words: ordnance science and technology, flow control, vortex-induced vibration, Lorentz force, oscillatory suppression