The superfluid Reynolds number and the transition from potential flow to turbulence in superfluid $^4$He at mK temperatures

摘要

This comment is on Phys.Rev.Lett. 144, 155302 (2015) by M.T. Reeves, T.P.Billam, B.P. Anderson, and A.S. Bradley "Identifying a superfluid Reynoldsnumber via dynamical similarity" where a new superfluid Reynolds number isintroduced. This definition is shown to be useful in the data analysis of thefinite lifetime of turbulence observed with an oscillating sphere in superfluidhelium at mK temperatures in a small velocity interval $\Delta v =(v-v_c)$ justabove the critical velocity $v_c$. The very rapid increase of the lifetime withincreasing superfluid Reynolds number is compared with the "supertransient"turbulence observed in classical pipe flow.