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Observation of Bistable Turbulence in Quasi-Two-Dimensional Superflow
E Varga1, V Vadakkumbatt1, A J Shook1
1Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada.
Physical Review Letters
|July 24, 2020
Summary
Turbulent flow in two dimensions can surprisingly form large-scale order. This study observed two stable turbulent states in superfluid helium-4, explained by opposing large-scale flow regions.
Area of Science:
- Fluid dynamics
- Quantum turbulence
- Condensed matter physics
Background:
- Two-dimensional turbulence typically develops large-scale order, contrasting with 3D turbulence.
- Superfluid helium-4 exhibits unique properties like zero viscosity and quantized vortices.
Purpose of the Study:
- To investigate turbulent flow behavior in a nearly two-dimensional channel of superfluid helium-4.
- To understand the emergence of order and potential bistability in such a system.
Main Methods:
- Experimental observation of steady-state flow in a nearly two-dimensional channel.
- Utilizing superfluid helium-4 with its unique properties of vanishing viscosity and discrete vorticity.
Main Results:
- Observed unusual turbulent behavior in steady-state flow.
- Identified two distinct, bistable turbulent states for specific experimental parameters.
- Linked bistability to the formation of large-scale regions with opposite vorticity.
Conclusions:
- Turbulence in 2D superfluid helium-4 can exhibit bistability.
- The presence of large-scale regions of opposing vorticity is key to this observed bistability.
- This finding challenges conventional understanding of turbulence and order in 2D systems.
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