Control of the Cylinder Wake Instabilities by an External Magnetic Field

The standard cylinder wake is considered for the magnetohydrodynamic (MHD) case: The fluid is electrically conducting and exposed to an external uniform magnetic field of different directions. In general, the magnetic field stabilizes the flow, the vortex street can be suppressed for each Re. A numerical simulation of the time-dependent flow as well as a simple analytical stability analysis will be presented and compared with available and own experiments. The experimentally found tendency of an increasing level of low-frequency perturbations for an increasing magnetic field will be discussed and compared with the analytical stability analysis. Typical features of the MHD case will be presented: Drag increase, up- and downstream wakes, surface pressure redistribution, recirculation bubbles at high Re, etc.