{"page":"3023-3054","year":"2024","citation":{"ama":"Winkler M. Externally forced blow-up and optimal spaces for source regularity in the two-dimensional Navier–Stokes system. Mathematische Annalen. 2024;391(2):3023-3054. doi:10.1007/s00208-024-02987-6","apa":"Winkler, M. (2024). Externally forced blow-up and optimal spaces for source regularity in the two-dimensional Navier–Stokes system. Mathematische Annalen, 391(2), 3023–3054. https://doi.org/10.1007/s00208-024-02987-6","chicago":"Winkler, Michael. “Externally Forced Blow-up and Optimal Spaces for Source Regularity in the Two-Dimensional Navier–Stokes System.” Mathematische Annalen 391, no. 2 (2024): 3023–54. https://doi.org/10.1007/s00208-024-02987-6.","short":"M. Winkler, Mathematische Annalen 391 (2024) 3023–3054.","bibtex":"@article{Winkler_2024, title={Externally forced blow-up and optimal spaces for source regularity in the two-dimensional Navier–Stokes system}, volume={391}, DOI={10.1007/s00208-024-02987-6}, number={2}, journal={Mathematische Annalen}, publisher={Springer Science and Business Media LLC}, author={Winkler, Michael}, year={2024}, pages={3023–3054} }","mla":"Winkler, Michael. “Externally Forced Blow-up and Optimal Spaces for Source Regularity in the Two-Dimensional Navier–Stokes System.” Mathematische Annalen, vol. 391, no. 2, Springer Science and Business Media LLC, 2024, pp. 3023–54, doi:10.1007/s00208-024-02987-6.","ieee":"M. Winkler, “Externally forced blow-up and optimal spaces for source regularity in the two-dimensional Navier–Stokes system,” Mathematische Annalen, vol. 391, no. 2, pp. 3023–3054, 2024, doi: 10.1007/s00208-024-02987-6."},"title":"Externally forced blow-up and optimal spaces for source regularity in the two-dimensional Navier–Stokes system","_id":"63248","user_id":"31496","publisher":"Springer Science and Business Media LLC","publication":"Mathematische Annalen","issue":"2","doi":"10.1007/s00208-024-02987-6","publication_status":"published","abstract":[{"lang":"eng","text":"Abstract\r\n The Navier–Stokes system \r\n \r\n $$\\begin{aligned} \\left\\{ \\begin{array}{l} u_t + (u\\cdot \\nabla ) u =\\Delta u+\\nabla P + f(x,t), \\\\ \\nabla \\cdot u=0, \\end{array} \\right. \\end{aligned}$$\r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n u\r\n t\r\n \r\n +\r\n \r\n (\r\n u\r\n ·\r\n ∇\r\n )\r\n \r\n u\r\n =\r\n Δ\r\n u\r\n +\r\n ∇\r\n P\r\n +\r\n f\r\n \r\n (\r\n x\r\n ,\r\n t\r\n )\r\n \r\n ,\r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n ∇\r\n ·\r\n u\r\n =\r\n 0\r\n ,\r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n is considered along with homogeneous Dirichlet boundary conditions in a smoothly bounded planar domain \r\n \r\n $$\\Omega $$\r\n \r\n Ω\r\n \r\n \r\n . It is firstly, inter alia, observed that if \r\n \r\n $$T>0$$\r\n \r\n \r\n T\r\n >\r\n 0\r\n \r\n \r\n \r\n and \r\n \r\n $$\\begin{aligned} \\int _0^T \\bigg \\{ \\int _\\Omega |f(x,t)| \\cdot \\ln ^\\frac{1}{2} \\big (|f(x,t)|+1\\big ) dx \\bigg \\}^2 dt <\\infty , \\end{aligned}$$\r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n ∫\r\n 0\r\n T\r\n \r\n \r\n {\r\n \r\n \r\n ∫\r\n Ω\r\n \r\n \r\n |\r\n f\r\n \r\n (\r\n x\r\n ,\r\n t\r\n )\r\n \r\n |\r\n \r\n ·\r\n \r\n ln\r\n \r\n 1\r\n 2\r\n \r\n \r\n \r\n (\r\n \r\n \r\n |\r\n f\r\n \r\n (\r\n x\r\n ,\r\n t\r\n )\r\n \r\n |\r\n \r\n +\r\n 1\r\n \r\n )\r\n \r\n d\r\n x\r\n \r\n \r\n }\r\n \r\n 2\r\n \r\n d\r\n t\r\n <\r\n ∞\r\n ,\r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n then for all divergence-free \r\n \r\n $$u_0\\in L^2(\\Omega ;{\\mathbb {R}}^2)$$\r\n \r\n \r\n \r\n u\r\n 0\r\n \r\n ∈\r\n \r\n L\r\n 2\r\n \r\n \r\n (\r\n Ω\r\n ;\r\n \r\n \r\n R\r\n \r\n 2\r\n \r\n )\r\n \r\n \r\n \r\n \r\n , a corresponding initial-boundary value problem admits a weak solution u with \r\n \r\n $$u|_{t=0}=u_0$$\r\n \r\n \r\n \r\n \r\n u\r\n |\r\n \r\n \r\n t\r\n =\r\n 0\r\n \r\n \r\n =\r\n \r\n u\r\n 0\r\n \r\n \r\n \r\n \r\n . For any positive and nondecreasing \r\n \r\n $$L\\in C^0([0,\\infty ))$$\r\n \r\n \r\n L\r\n ∈\r\n \r\n C\r\n 0\r\n \r\n \r\n (\r\n \r\n [\r\n 0\r\n ,\r\n ∞\r\n )\r\n \r\n )\r\n \r\n \r\n \r\n \r\n such that \r\n \r\n $$\\begin{aligned} \\frac{L(\\xi )}{\\ln ^\\frac{1}{2} \\xi } \\rightarrow 0 \\qquad \\text{ as } \\xi \\rightarrow \\infty , \\end{aligned}$$\r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n L\r\n (\r\n ξ\r\n )\r\n \r\n \r\n \r\n ln\r\n \r\n 1\r\n 2\r\n \r\n \r\n ξ\r\n \r\n \r\n →\r\n 0\r\n \r\n \r\n as\r\n \r\n ξ\r\n →\r\n ∞\r\n ,\r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n this is complemented by a statement on nonexistence of such a solution in the presence of smooth initial data and a suitably constructed \r\n \r\n $$f:\\Omega \\times (0,T)\\rightarrow {\\mathbb {R}}^2$$\r\n \r\n \r\n f\r\n :\r\n Ω\r\n ×\r\n \r\n (\r\n 0\r\n ,\r\n T\r\n )\r\n \r\n →\r\n \r\n \r\n R\r\n \r\n 2\r\n \r\n \r\n \r\n \r\n fulfilling \r\n \r\n $$\\begin{aligned} \\int _0^T \\bigg \\{ \\int _\\Omega |f(x,t)| \\cdot L\\big (|f(x,t)|\\big ) dx \\bigg \\}^2 dt < \\infty . \\end{aligned}$$\r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n ∫\r\n 0\r\n T\r\n \r\n \r\n {\r\n \r\n \r\n ∫\r\n Ω\r\n \r\n \r\n |\r\n f\r\n \r\n (\r\n x\r\n ,\r\n t\r\n )\r\n \r\n |\r\n \r\n ·\r\n \r\n L\r\n \r\n (\r\n \r\n |\r\n f\r\n \r\n (\r\n x\r\n ,\r\n t\r\n )\r\n \r\n |\r\n \r\n )\r\n \r\n d\r\n x\r\n \r\n \r\n \r\n }\r\n \r\n 2\r\n \r\n d\r\n t\r\n <\r\n ∞\r\n .\r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n This resolves a fine structure in the borderline case \r\n \r\n $$p=1$$\r\n \r\n \r\n p\r\n =\r\n 1\r\n \r\n \r\n \r\n and \r\n \r\n $$q=2$$\r\n \r\n \r\n q\r\n =\r\n 2\r\n \r\n \r\n \r\n appearing in results on existence of weak solutions for sources in \r\n \r\n $$L^q((0,T);L^p(\\Omega ;{\\mathbb {R}}^2))$$\r\n \r\n \r\n \r\n L\r\n q\r\n \r\n \r\n (\r\n \r\n (\r\n 0\r\n ,\r\n T\r\n )\r\n \r\n ;\r\n \r\n L\r\n p\r\n \r\n \r\n (\r\n Ω\r\n ;\r\n \r\n \r\n R\r\n \r\n 2\r\n \r\n )\r\n \r\n )\r\n \r\n \r\n \r\n \r\n when \r\n \r\n $$p\\in (1,\\infty ]$$\r\n \r\n \r\n p\r\n ∈\r\n (\r\n 1\r\n ,\r\n ∞\r\n ]\r\n \r\n \r\n \r\n and \r\n \r\n $$q\\in [1,\\infty ]$$\r\n \r\n \r\n q\r\n ∈\r\n [\r\n 1\r\n ,\r\n ∞\r\n ]\r\n \r\n \r\n \r\n satisfy \r\n \r\n $$\\frac{1}{p}+\\frac{1}{q}\\le \\frac{3}{2}$$\r\n \r\n \r\n \r\n 1\r\n p\r\n \r\n +\r\n \r\n 1\r\n q\r\n \r\n ≤\r\n \r\n 3\r\n 2\r\n \r\n \r\n \r\n \r\n , and on nonexistence if here \r\n \r\n $$p\\in [1,\\infty )$$\r\n \r\n \r\n p\r\n ∈\r\n [\r\n 1\r\n ,\r\n ∞\r\n )\r\n \r\n \r\n \r\n and \r\n \r\n $$q\\in [1,\\infty )$$\r\n \r\n \r\n q\r\n ∈\r\n [\r\n 1\r\n ,\r\n ∞\r\n )\r\n \r\n \r\n \r\n are such that \r\n \r\n $$\\frac{1}{p}+\\frac{1}{q}>\\frac{3}{2}$$\r\n \r\n \r\n \r\n 1\r\n p\r\n \r\n +\r\n \r\n 1\r\n q\r\n \r\n >\r\n \r\n 3\r\n 2\r\n \r\n \r\n \r\n \r\n ."}],"language":[{"iso":"eng"}],"author":[{"last_name":"Winkler","full_name":"Winkler, Michael","first_name":"Michael","id":"31496"}],"status":"public","type":"journal_article","publication_identifier":{"issn":["0025-5831","1432-1807"]},"volume":391,"date_updated":"2025-12-18T20:13:05Z","intvolume":" 391","date_created":"2025-12-18T19:02:09Z"}