Quantum Turbulence in Coflow of Superfluid $$^{4}$$4He

We study numerically nonuniform quantum turbulence of coflow in a square channel by the vortex filament model. Coflow means that superfluid velocity $$\varvec{v}_\mathrm{s}$$vs and normal fluid velocity $$\varvec{v}_\mathrm{n}$$vn flow in the same direction. Quantum turbulence for thermal counterflow has been long studied theoretically and experimentally. In recent years, experiments of coflow have been performed to observe different features from thermal counterflow. By supposing that $$\varvec{v}_\mathrm{s}$$vs is uniform and $$\varvec{v}_\mathrm{n}$$vn takes the Hagen–Poiseuille profile, simulations find that quantized vortices are distributed inhomogeneously. Vortices like to accumulate on the surface of a cylinder with $$\varvec{v}_\mathrm{s} \simeq \varvec{v}_\mathrm{n}$$vs≃vn. Consequently, the vortex configuration becomes degenerate from three-dimensional to two-dimensional.