NUMERICAL INVESTIGATION OF THE FLOW PROPERTIES OF HE-II

In the framework of the reconnecting vortex-tangle model, flow properties of He II were studied numerically. The Crank-Nicolson method was used to calculate the motion of quantized He-4 vortices, assuming smooth walls in infinitely long channels, applying periodic boundary conditions in the direction of the flow, and with friction coefficients alpha = 0.1 and alpha' = 0. Flow channels with square and circular cross sections and infinitely wide slits were studied. The superfluid velocity profile was assumed to be flat; the normal-component velocity profile was either flat or parabolic. Special interest was paid to the time-averaged line-length density and the average mutual-friction force density as functions of the difference between the average normal-fluid velocity and the externally applied superfluid velocity. The influence of the periodicity length on the calculated flow properties was determined. The results were compared with experiment.