Stability and dissipation of laminar vortex flow in superfluid ³He-B

A central question in the dynamics of vortex lines in superfluids is dissipation on approaching the zero temperature limit 𝑇→0. From both NMR measurements and vortex filament calculations, we find that vortex flow remains laminar up to large Reynolds numbers Re_𝛼∼10³ in a cylinder filled with ³He−B. This is different from viscous fluids and superfluid ⁴He, where the corresponding responses are turbulent. In ³He−B, laminar vortex flow is possible in the bulk volume even in the presence of sizable perturbations from axial symmetry to below 0.2⁢𝑇_c. The laminar flow displays no excess dissipation beyond mutual friction, which vanishes in the 𝑇→0 limit, in contrast with turbulent vortex motion where dissipation has been earlier measured to approach a large 𝑇-independent value at 𝑇 ≲ 0.2⁢𝑇_c.