Turbulent helium II flow through different narrow channels

Turbulent helium II flow is investigated in an annular gap of about 10 μm width and in superfilters with a pore size ≤ 0.1 μm. Of primary interest is the flow behavior at high mass flow rates. In the cases of both an annular gap and superfilters, deviations from the low-flow-rate behavior are found, which can be attributed to different reasons. Both systems with their separately determined characteristics are then combined in a parallel arrangement in order to study the flow in a channel system with nonuniform dimensions, as is realized, e.g., in a porous plug. The parallel system permits checks of different hypotheses on the flow behavior. The results show that certain simplistic ideas about the internal geometry of a porous plug are inadequate for the hydrodynamic treatment