On the relevance of bubbles and potential flows for stellar convection

TL;DR

This paper critically examines a new convection theory for stellar physics based on bubbles in potential flows, identifying fundamental issues that undermine its physical applicability and effectiveness.

Contribution

It provides a detailed critique of Pasetto et al.'s proposed convection model, highlighting its theoretical flaws and limitations in capturing stellar convection.

Findings

Identifies problems in the derivation of the new convection theory.

Shows the spherical bubble potential flow framework is inadequate for stellar convection.

Concludes the proposed theory is not physically applicable.

Abstract

Recently Pasetto et al. have proposed a new method to derive a convection theory appropriate for the implementation in stellar evolution codes. Their approach is based on the simple physical picture of spherical bubbles moving within a potential flow in dynamically unstable regions, and a detailed computation of the bubble dynamics. Based on this approach the authors derive a new theory of convection which is claimed to be parameter free, non-local and time-dependent. This is a very strong claim, as such a theory is the holy grail of stellar physics. Unfortunately we have identified several distinct problems in the derivation which ultimately render their theory inapplicable to any physical regime. In addition we show that the framework of spherical bubbles in potential flows is unable to capture the essence of stellar convection, even when equations are derived correctly.