{"title":"Uniqueness of Mild Solutions to the Navier-Stokes Equations in Weak-type \\(L^d\\) Space","authors":"Zhirun Zhan","doi":"10.1007/s00021-025-00945-z","DOIUrl":null,"url":null,"abstract":"<div><p>This paper deals with the uniqueness of mild solutions to the forced or unforced Navier-Stokes equations in the whole space. It is known that the uniqueness of mild solutions to the unforced Navier-Stokes equations holds in <span>\\(L^{\\infty }(0,T;L^d({\\mathbb {R}}^d))\\)</span> when <span>\\(d\\ge 4\\)</span>, and in <span>\\(C([0,T];L^d({\\mathbb {R}}^d))\\)</span> when <span>\\(d\\ge 3\\)</span>. As for the forced Navier-Stokes equations, when <span>\\(d\\ge 3\\)</span> the uniqueness of mild solutions in <span>\\(C([0,T];L^{d,\\infty }({\\mathbb {R}}^d))\\)</span> with force <i>f</i> and initial data <span>\\(u_{0}\\)</span> in appropriate Lorentz spaces is known. In this paper we show that for <span>\\(d\\ge 3\\)</span>, the uniqueness of mild solutions to the forced Navier-Stokes equations in <span>\\( C((0,T];{\\widetilde{L}}^{d,\\infty }({\\mathbb {R}}^d))\\cap L^\\beta (0,T;{\\widetilde{L}}^{d,\\infty }({\\mathbb {R}}^d))\\)</span> for <span>\\(\\beta >2d/(d-2)\\)</span> holds when there is a mild solution in <span>\\(C([0,T];{\\widetilde{L}}^{d,\\infty }({\\mathbb {R}}^d))\\)</span> with the same initial data and force. Here <span>\\({\\widetilde{L}}^{d,\\infty }\\)</span> is the closure of <span>\\({L^{\\infty }\\cap L^{d,\\infty }}\\)</span> with respect to <span>\\(L^{d,\\infty }\\)</span> norm.</p></div>","PeriodicalId":649,"journal":{"name":"Journal of Mathematical Fluid Mechanics","volume":"27 3","pages":""},"PeriodicalIF":1.3000,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Mathematical Fluid Mechanics","FirstCategoryId":"100","ListUrlMain":"https://link.springer.com/article/10.1007/s00021-025-00945-z","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATHEMATICS, APPLIED","Score":null,"Total":0}
引用次数: 0
Abstract
This paper deals with the uniqueness of mild solutions to the forced or unforced Navier-Stokes equations in the whole space. It is known that the uniqueness of mild solutions to the unforced Navier-Stokes equations holds in \(L^{\infty }(0,T;L^d({\mathbb {R}}^d))\) when \(d\ge 4\), and in \(C([0,T];L^d({\mathbb {R}}^d))\) when \(d\ge 3\). As for the forced Navier-Stokes equations, when \(d\ge 3\) the uniqueness of mild solutions in \(C([0,T];L^{d,\infty }({\mathbb {R}}^d))\) with force f and initial data \(u_{0}\) in appropriate Lorentz spaces is known. In this paper we show that for \(d\ge 3\), the uniqueness of mild solutions to the forced Navier-Stokes equations in \( C((0,T];{\widetilde{L}}^{d,\infty }({\mathbb {R}}^d))\cap L^\beta (0,T;{\widetilde{L}}^{d,\infty }({\mathbb {R}}^d))\) for \(\beta >2d/(d-2)\) holds when there is a mild solution in \(C([0,T];{\widetilde{L}}^{d,\infty }({\mathbb {R}}^d))\) with the same initial data and force. Here \({\widetilde{L}}^{d,\infty }\) is the closure of \({L^{\infty }\cap L^{d,\infty }}\) with respect to \(L^{d,\infty }\) norm.
期刊介绍:
The Journal of Mathematical Fluid Mechanics (JMFM)is a forum for the publication of high-quality peer-reviewed papers on the mathematical theory of fluid mechanics, with special regards to the Navier-Stokes equations. As an important part of that, the journal encourages papers dealing with mathematical aspects of computational theory, as well as with applications in science and engineering. The journal also publishes in related areas of mathematics that have a direct bearing on the mathematical theory of fluid mechanics. All papers will be characterized by originality and mathematical rigor. For a paper to be accepted, it is not enough that it contains original results. In fact, results should be highly relevant to the mathematical theory of fluid mechanics, and meet a wide readership.