Emergent Universal Drag Law in a Model of Superflow

TL;DR

This paper demonstrates a universal drag law in superfluid flow, showing that quantum turbulence exhibits classical-like drag behavior across different obstacle geometries and Reynolds numbers, confirmed through numerical simulations.

Contribution

It introduces the existence of a universal drag law in superfluid wake flows and proposes a method for experimental measurement of superfluid drag forces.

Findings

Universal drag law confirmed in superfluid wake flows.

Quantized vortices nucleation underpins the drag behavior.

Method proposed for experimental measurement of superfluid drag.

Abstract

Despite the fundamentally different dissipation mechanisms, many laws and phenomena of classical turbulence equivalently manifest in quantum turbulence. The Reynolds law of dynamical similarity states that two objects of same geometry across different length scales are hydrodynamically equivalent under the same Reynolds number, leading to a universal drag coefficient law. In this work we confirm the existence of a universal drag law in a superfluid wake, facilitated by the nucleation of quantized vortices. We numerically study superfluid flow across a range of Reynolds numbers for the paradigmatic classical hard-wall and the Gaussian obstacle, popular in experimental quantum hydrodynamics. In addition, we provide a feasible method for measuring superfluid drag forces in an experimental environment using control volumes.