Analysis of a nonisothermal Maxwell--Stefan system with degenerate thermal conductivity

Abstract: We prove the global-in-time existence of weak solutions for the Maxwell--Stefan--Fourier system with physically motivated degenerate thermal conductivity $κ(θ)=θ<sup>α$, for $0&lt;α\leq2$. In contrast to existing nonisothermal compressible theories based on nondegenerate conductivities, the entropy inequality no longer gives control of the quantities $\nablaθ$ and $\nabla \logθ$. The main new ingredient is a renormalized energy estimate, which yields compactness of the temperature and allows the identification of the degenerate heat flux.