Breakdown of Potential Flow to Turbulence around a Sphere Oscillating in Superfluid He-4 above the Critical Velocity

W. Schoepe, R. Hänninen, M. Niemetz

The onset of turbulent flow around an oscillating sphere in superfluid ${}^4$He is known to occur at a critical velocity $v_c\sim \sqrt{\kappa \omega }$ where $\kappa$ is the circulation quantum and…