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Fluid pinch-off in superfluid and normal 4He.
J C Burton1, J E Rutledge, P Taborek
1Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA.
Summary
High-speed videos reveal liquid helium (4He) droplet pinch-off dynamics are similar in normal and superfluid states. The fluid neck evolution follows power laws, with exponents n=2/3 near pinch-off and n=2/5 in an intermediate regime.
Area of Science:
- Fluid Dynamics
- Low-Temperature Physics
- Quantum Fluids
Background:
- Understanding the pinch-off dynamics of low-viscosity fluids is crucial for various physical phenomena.
- Liquid helium (4He) exhibits unique quantum properties in its superfluid state, necessitating investigation into its fluid behavior under extreme conditions.
Purpose of the Study:
- To investigate the pinch-off dynamics of liquid 4He droplets across a range of temperatures (1.33 K to 4.8 K).
- To compare the pinch-off behavior in both the normal and superfluid states of liquid 4He.
- To characterize the evolution of the minimum neck radius during the pinch-off process using power-law analysis.
Main Methods:
- High-speed video recording of liquid 4He droplet pinch-off.
- Image analysis to determine the minimum neck radius (rmin) as a function of time to pinch-off (tau).
- Temperature control of the liquid 4He droplets within the range of 1.33 K to 4.8 K.
Main Results:
- No qualitative differences in pinch-off behavior were observed between the normal and superfluid states of 4He.
- The final stage of pinch-off resembles a cone piercing a sphere, consistent with other low-viscosity fluids.
- The minimum neck radius evolution follows power laws (rmin ∝ τα), with n=2/3 observed near pinch-off and at the onset of the process.
- An intermediate crossover regime was identified, characterized by a power-law exponent of n=2/5.
Conclusions:
- The pinch-off dynamics of liquid 4He are remarkably similar in both normal and superfluid phases.
- The observed power-law scaling provides quantitative insights into the fluid mechanics of droplet pinch-off.
- The findings contribute to a fundamental understanding of quantum fluid behavior and low-viscosity fluid dynamics.
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