Two-dimensional simulation of vortex points and tracer particles in counterflowing He-II.

The article presents results obtained based on numerical simulation of two-dimensional vortex points and inertial tracer particles in two-component counterflowing superfluid He-II. In the low temperature limit (no normal fluid, no friction) our model would reduce to Onsager's famous vortex gas. The flow of the normal component of the He-II is assumed uniform, while the superfluid velocity field is induced by vortex points which model three-dimensional quantized vortex lines. Probability density functions of velocity and acceleration of tracer particles and superfluid velocity field are obtained. We find that tails of probability distributions follow power-laws with various exponents, except in the case of sufficiently coarse-grained superfluid velocity field, where Gaussian shape is observed. The decay of the number of vortices is also studied, yielding results in agreement with Vinen's phenomenological model of quantum turbulence. [ABSTRACT FROM AUTHOR]