Dynamics of vortex tangle without mutual friction in superfluid 4 He

摘要: A recent experiment has shown that a tangle of quantized vortices in superfluid ${}^{4}\mathrm{He}$ decayed even at mK temperatures where the normal fluid was negligible and no mutual friction worked. Motivated by this experiment, work studies numerically dynamics vortex without friction, thus showing self-similar cascade process, whereby large loops break up to smaller ones, proceeds is closely related with its free decay. This process which may be covered higher just one zero temperature Feynman proposed long ago. The full Biot-Savart calculation made for dilute vortices, while localized induction approximation used dense tangle. former finds elementary scenario: reconnection excites waves along them makes kinked, could suppressed if kinked parts reconnect they belong to, dividing into small loops. latter simulation under shows such actually self-similarly continues make vortices. Considering interatomic size longer keep picture vortex, leads decay line density. presence supported also investigating classification type distribution density consistent solution Vinen's equation originally derived on basis idea homogeneous turbulence process. revealed an intrinsic system from fluid. obtained result compared theory discusses Kelvin wave sound radiation.