Observation of the turbulent flow in superfluid 4He using a vibrating wire

Transition to Turbulence for a Quartz Tuning Fork in Superfluid 4He

“…We associate this with extra drag arising from quantised vortex lines, so we will loosely refer to this as the "turbulent regime" to distinguish it from the "laminar regime" without vortex lines at lower velocities. Similar behaviour has been observed previously for forks [28,29,31,33], vibrating grids [17,18], vibrating wire resonators [1,2,[6][7][8][9][10][11] and oscillating spheres [19][20][21][22] in superfluid 4 He.…”

“…This irreproducibility of fork behaviour may limit their use as reliable cryogenic tools at the lowest temperatures. However, measurements in the new cell now revealed switching between the laminar and turbulent regimes and hysteresis, allowing for comparison with similar observations made previously with wire resonators [1,2,[6][7][8][9][10][11] and oscillating spheres [19][20][21][22]. A typical response curve, taken at 8 mK and 1 bar pressure, is shown in figure 5.…”

“…At higher temperatures the transition is less clear, somewhat masked due to increased linear damping. Nevertheless, the turbulent drag force is found to be independent of temperature below 1 K. In further investigations of the transition region at low temperatures, we find hysteresis and switching behaviour similar to that observed for vibrating wires and spheres [1,2,[6][7][8][9][10][11][19][20][21][22]. There are however some important differences which we discuss below.…”

“…There is much interest in the behaviour of vibrating objects immersed in the quantum fluids 3 He and 4 He. The recent expansion in activity has been largely inspired by developments in the study of turbulence, with several groups investigating oscillating wires [1][2][3][4][5][6][7][8][9][10][11][12], grids [13][14][15][16][17][18], spheres [19][20][21][22][23][24][25] and quartz tuning forks [26][27][28][29][30][31][32][33]. Mechanical probes give much information about the dynamics of superfluids and their excitations.…”

“…In superfluid 3 He advances in experimental techniques have enabled studies of the production and decay of turbulence by vibrating wires and grids [4,5,[13][14][15][16]. In superfluid 4 He the turbulent damping of an oscillating grid has been probed [17,18], and studies of spheres [19][20][21][22] and vibrating wires [1,2,[6][7][8][9][10][11] show common features such as hysteresis around the turbulent transition, likely related to the properties of remnant vortices. Recent attention has been given to the production of quantum turbulence by quartz tuning forks [28,31,33].…”