Turbulent drag on a low-frequency vibrating grid in superfluid He-4 at very low temperatures

Bradley, D. I. and Fisher, S. N. and Guenault, A. M. and Haley, R. P. and Kumar, Mukesh and Lawson, C. R. and Schanen, Roch and McClintock, P. V. E. and Munday, Lydia and Pickett, G. R. and Poole, Malcolm and Tsepelin, V. and Williams, Paul (2012) Turbulent drag on a low-frequency vibrating grid in superfluid He-4 at very low temperatures. Physical review b, 85 (22). -. ISSN 1098-0121

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Abstract

We present measurements of the dissipative turbulent drag on a vibrating grid in superfluid He-4 over a wide range of (low) frequencies. At high velocities, the dissipative drag is independent of frequency and is approximately the same as that measured in normal liquid He-4. We present measurements on a similar grid in superfluid He-3-B at low temperatures which shows an almost identical turbulent drag coefficient at low frequencies. However, the turbulent drag in He-3-B is substantially higher at higher frequencies. We also present measurements of the inertial drag coefficient for grid turbulence in He-4. The inertial drag coefficient is significantly reduced by turbulence in both superfluid and normal liquid He-4.

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