On the continuity in time of solutions to a generalized Navier--Stokes--Fourier system

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Hauptverfasser: Bulíček, Miroslav, Kaplický, Petr, Wintrová, Lucie
Format: Preprint
Veröffentlicht: 2025
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author Bulíček, Miroslav
Kaplický, Petr
Wintrová, Lucie
author_facet Bulíček, Miroslav
Kaplický, Petr
Wintrová, Lucie
contents We consider the flow of a generalized non-Newtonian incompressible heat-conducting fluid in a~bounded two-dimensional domain, subject to Dirichlet boundary conditions for velocity and temperature. The fluid obeys a power-law constitutive relation for the Cauchy stress with exponent~$p$. For $p\geq 2$ and finite-energy initial data, we establish the existence of a global-in-time weak solution that satisfies the entropy equality. The novelty of this work is the rigorous proof of time continuity of the temperature in $L^1(Ω)$, a property not previously established in this setting. Furthermore, we prove regularity and time continuity for a weak solution of the entropy equation with a convective term and an $L^1$ right-hand side under minimal assumptions on the velocity regularity, in arbitrary spatial dimensions. We show that this continuity is equivalently described by vanishing dissipation on high level sets, a truncated variational inequality for admissible test functions, or the associated equality. This reveals the connection between energy dissipation, weak stability, and temporal regularity.
format Preprint
id arxiv_https___arxiv_org_abs_2510_21218
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On the continuity in time of solutions to a generalized Navier--Stokes--Fourier system
Bulíček, Miroslav
Kaplický, Petr
Wintrová, Lucie
Analysis of PDEs
35Q30, 35K61, 35K92, 37L15, 76D03, 76E30
We consider the flow of a generalized non-Newtonian incompressible heat-conducting fluid in a~bounded two-dimensional domain, subject to Dirichlet boundary conditions for velocity and temperature. The fluid obeys a power-law constitutive relation for the Cauchy stress with exponent~$p$. For $p\geq 2$ and finite-energy initial data, we establish the existence of a global-in-time weak solution that satisfies the entropy equality. The novelty of this work is the rigorous proof of time continuity of the temperature in $L^1(Ω)$, a property not previously established in this setting. Furthermore, we prove regularity and time continuity for a weak solution of the entropy equation with a convective term and an $L^1$ right-hand side under minimal assumptions on the velocity regularity, in arbitrary spatial dimensions. We show that this continuity is equivalently described by vanishing dissipation on high level sets, a truncated variational inequality for admissible test functions, or the associated equality. This reveals the connection between energy dissipation, weak stability, and temporal regularity.
title On the continuity in time of solutions to a generalized Navier--Stokes--Fourier system
topic Analysis of PDEs
35Q30, 35K61, 35K92, 37L15, 76D03, 76E30
url https://arxiv.org/abs/2510.21218