Abstract
We have studied the transition between pure potential flow and turbulent flow around a quartz tuning fork resonator in superfluid at millikelvin temperatures. Turbulent flow is identified by an additional drag force on the fork prongs due to the creation of quantized vortices. When driven at a constant driving force amplitude, the transition to turbulence causes an abrupt decrease in the velocity amplitude of the prongs. For a range of driving forces, continuous switching is observed between the two flow states. We have made a statistical study of the switching characteristics and of the lifetimes of the unstable states. We find a characteristic velocity which separates quasistable turbulent flow at higher velocities and quasistable potential flow at lower velocities. We show that the potential-to-turbulent flow transition is driven by random processes involving remanent vortices pinned to the prongs.
5 More- Received 11 February 2014
- Revised 15 April 2014
DOI:https://doi.org/10.1103/PhysRevB.89.214503
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Published by the American Physical Society