Developed quantum turbulence and its decay

This article is primarily a review of our knowledge of the correspondence between classical and quantum turbulence, though it is interspersed with a few new interpretations. This review is deemed timely because recent work in quantum turbulence promises to provide a better understanding of aspects of classical turbulence, though the two fields of turbulence have similarities as well as differences. We pay a particular attention to the conceptually simplest case of zero temperature limit where quantum turbulence consists of a tangle of quantized vortex line and represents a simple prototype of turbulence. At finite temperature, we anchor ourselves at the level of two-fluid description of the superfluid state-consisting of a normal viscous fluid and a frictionless superfluid-and review much of the available knowledge on quantum turbulence in liquid helium (both He II and 3He-B). We consider counterflows in which the normal and superfluid components flow against each other, as well as co-flows in which the direction of the two fluids is the same. We discuss experimental methods, phenomenological results as well as key theoretical concepts.