On Hodge decomposition, effective viscous flux and compressible Navier-Stokes

TL;DR

This paper investigates the relationship between Hodge decomposition and the regularizing effects of the effective viscous flux in compressible Navier-Stokes equations, focusing on global weak solutions with spatially mollified density-dependent viscosities.

Contribution

It extends the understanding of the connection between Hodge decomposition and viscous flux regularization to cases with density-dependent viscosities.

Findings

Established global existence of weak solutions under new conditions.

Analyzed the impact of spatial mollification on viscosity.

Connected Hodge decomposition properties to solution regularity.

Abstract

It has been known, since the pioneering works by Serre, Hoff, Va\u{i}gant-Kazhikhov, Lions and Feireisl, among others, the regularizing properties of the effective viscous flux and its characterization as the function whose gradient is the gradient part in the Hodge decomposition of the Newtonian force of the fluid, when the shear viscosity of the fluid is constant. In this article, we explore further the connection between the Hodge decomposition of the Newtonian force and the regularizing properties of its gradient part, by addressing the problem of the global existence of weak solutions for compressible Navier-Stokes equations with both viscosities depending on a spatial mollification of the density.