On well-posedness of a mildly dissipative family of active scalar equations in borderline Sobolev spaces

Fuente: arXiv
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Autori principali: Kumar, Anuj, Martinez, Vincent R.
Natura: Preprint
Pubblicazione: 2023
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author Kumar, Anuj
Martinez, Vincent R.
author_facet Kumar, Anuj
Martinez, Vincent R.
contents This paper considers a family of active scalar equations which modify the generalized surface quasi-geostrophic (gSQG) equations through its constitutive law and a dissipative perturbation. These modifications are characteristically mild in the sense that they are logarithmic. The problem of well posedness, in the sense of Hadamard, is then studied in a borderline setting of regularity in analogy to the scaling-critical spaces of the gSQG equations. A novelty of the system considered is the nuanced form of smoothing provided by the proposed mild form of dissipation, which is able to support global well-posedness at the Euler endpoint, but in a setting where the inviscid counterpart is known to be ill-posed. A novelty of the analysis lies in the simultaneous treatment of modifications in the constitutive law, dissipative mechanism, and functional setting, which the existing literature has typically treated separately. A putatively sharp relation is identified between each of the distinct system-modifiers that is consistent with previous studies that considered these modifications in isolation. This unified perspective is afforded by the introduction of a linear model equation, referred to as the protean system, that successfully incorporates the more delicate commutator structure collectively possessed by the gSQG family and upon which each facet of well-posedness can effectively be reduced to its study.
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id arxiv_https___arxiv_org_abs_2309_05844
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle On well-posedness of a mildly dissipative family of active scalar equations in borderline Sobolev spaces
Kumar, Anuj
Martinez, Vincent R.
Analysis of PDEs
76B03, 35Q35, 35Q86, 35B45
This paper considers a family of active scalar equations which modify the generalized surface quasi-geostrophic (gSQG) equations through its constitutive law and a dissipative perturbation. These modifications are characteristically mild in the sense that they are logarithmic. The problem of well posedness, in the sense of Hadamard, is then studied in a borderline setting of regularity in analogy to the scaling-critical spaces of the gSQG equations. A novelty of the system considered is the nuanced form of smoothing provided by the proposed mild form of dissipation, which is able to support global well-posedness at the Euler endpoint, but in a setting where the inviscid counterpart is known to be ill-posed. A novelty of the analysis lies in the simultaneous treatment of modifications in the constitutive law, dissipative mechanism, and functional setting, which the existing literature has typically treated separately. A putatively sharp relation is identified between each of the distinct system-modifiers that is consistent with previous studies that considered these modifications in isolation. This unified perspective is afforded by the introduction of a linear model equation, referred to as the protean system, that successfully incorporates the more delicate commutator structure collectively possessed by the gSQG family and upon which each facet of well-posedness can effectively be reduced to its study.
title On well-posedness of a mildly dissipative family of active scalar equations in borderline Sobolev spaces
topic Analysis of PDEs
76B03, 35Q35, 35Q86, 35B45
url https://arxiv.org/abs/2309.05844