Turbulent flows at cryogenic temperatures: a new frontier

Cryogenic helium is of significant value in generating, and studying, the highest possible Reynolds and Rayleigh number flows under controlled laboratory conditions, primarily due to its extremely low value of kinematic viscosity. We consider here critical helium gas and the two liquid phases, helium I and helium II. Such flows are already being generated and studied using suitable cryogenic equipment. We outline the current experiments and existing proposals for future studies that include gaseous and liquid helium I and II.