Vortex shedding frequency of a moving obstacle in a Bose–Einstein condensate

Abstract We experimentally investigate the periodic vortex shedding dynamics in a highly oblate Bose–Einstein condensate using moving penetrable Gaussian obstacle. The frequency f v is measured as function of obstacle velocity and characterized by linear relationship = ( ? c ) with being critical velocity. proportionality constant linearly decreased decrease strength, whereas approaches speed sound. When size increases, both are decreased. discuss possible association Strouhal number context universal superfluid. further investigated for an oscillating found to be consistent . obstacle’s maximum exceeds but its oscillation amplitude not large enough create dipole, we observe that vortices generated low-density boundary region trapped condensate, which attributed phonon emission from