Decay of Counterflow Quantum Turbulence in Superfluid 4He

We have simulated the decay of thermal counterflow quantum turbulence from a statistically steady state at T=1.9 K, with the assumption that the normal fluid is at rest during the decay. The results are consistent with the predictions of the Vinen equation (in essence the vortex line density decays as t−1). For the statistically steady state, we determine the parameter c2, which connects the curvature of the vortex lines and the mean separation of vortices. A formula connecting the parameter χ2 of the Vinen equation with c2 is shown to agree with the results of the simulations. Disagreement with experiment is discussed briefly.