Subcritical dissipation in three-dimensional superflows

Area of Science:

• Fluid Dynamics
• Quantum Mechanics
• Condensed Matter Physics

Background:

• Superfluidity describes frictionless flow in quantum fluids.
• Understanding flow dynamics around obstacles is crucial for experimental applications.
• Previous studies often focused on two-dimensional (2D) models.

Purpose of the Study:

• To investigate three-dimensional (3D) superflows past a circular cylinder.
• To analyze vortex dynamics and their impact on flow properties.
• To determine the critical velocity in 3D superflows and compare it to 2D.

Main Methods:

• Numerical integration of the nonlinear Schrödinger equation.
• Generation of 3D initial data from 2D vortex solutions.
• Observation of vortex behavior and interaction with the cylinder.

Main Results:

• Generation of quasistationary half-ring vortices pinned to the cylinder.
• Observation of 3D vortex stretching leading to dissipation and drag.
• Vortices are either dissipated or absorbed by the cylinder.
• The 3D critical velocity is found to be significantly lower than the 2D critical velocity.

Conclusions:

• Three-dimensional effects fundamentally alter superfluid flow dynamics compared to 2D.
• Dissipation and drag are significant in 3D superflows due to vortex stretching.
• The reduced critical velocity has important implications for experimental setups involving Bose-Einstein condensates and superfluid helium.