How can vorticity be produced in irrotationally forced flows?

TL;DR

This paper investigates how vorticity can be generated in flows that are initially irrotational, focusing on mechanisms like baroclinicity, rotation, and shear in a viscous fluid, with relevance to astrophysical phenomena such as supernovae.

Contribution

It analyzes the effects of baroclinicity, rotation, and shear on vorticity production in spherical, irrotational flows, especially in astrophysical contexts like the interstellar medium.

Findings

Baroclinicity can generate vorticity in irrotational flows.

Rotation influences vorticity production in viscous fluids.

Shear contributes to vorticity generation in the studied flows.

Abstract

A spherical hydrodynamical expansion flow can be described as the gradient of a potential. In that case no vorticity should be produced, but several additional mechanisms can drive its production. Here we analyze the effects of baroclinicity, rotation and shear in the case of a viscous fluid. Those flows resemble what happens in the interstellar medium. In fact in this astrophysical environment supernovae explosion are the dominant flows and, in a first approximation, they can be seen as spherical. One of the main difference is that in our numerical study we examine only weakly supersonic flows, while supernovae explosions are strongly supersonic.