Boundary-layer turbulence in experiments of quasi-Keplerian flows

TL;DR

This study uses numerical simulations to show that in quasi-Keplerian flows, turbulence is confined to boundary layers at high Reynolds numbers, challenging the expectation of turbulence in such flows.

Contribution

The paper demonstrates through simulations that turbulence in quasi-Keplerian flows remains confined to boundary layers and does not develop in the bulk at high Reynolds numbers.

Findings

Turbulence is confined to boundary layers at high Reynolds numbers.

Flow in the bulk relaminarizes as Reynolds number increases.

Supports that turbulence is unlikely in isothermal quasi-Keplerian flows.

Abstract

Most flows in nature and engineering are turbulent because of their large velocities and spatial scales. Laboratory experiments of rotating quasi-Keplerian flows, for which the angular velocity decreases radially but the angular momentum increases, are however laminar at Reynolds numbers exceeding one million. This is in apparent contradiction to direct numerical simulations showing that in these experiments turbulence transition is triggered by the axial boundaries. We here show numerically that as the Reynolds number increases turbulence becomes progressively confined to the boundary layers and the flow in the bulk fully relaminarizes. Our findings support that turbulence is unlikely to occur in isothermal constant density quasi-Keplerian flows.