{ "id": "1508.03318", "version": "v1", "published": "2015-08-13T19:38:13.000Z", "updated": "2015-08-13T19:38:13.000Z", "title": "Regularity Criterion to the axially symmetric Navier-Stokes Equations", "authors": [ "Dongyi Wei" ], "comment": "13 pages, 0 figures", "categories": [ "math.AP" ], "abstract": "Smooth solutions to the axially symmetric Navier-Stokes equations obey the following maximum principle:$\\|ru_\\theta(r,z,t)\\|_{L^\\infty}\\leq\\|ru_\\theta(r,z,0)\\|_{L^\\infty}.$ We first prove the global regularity of solutions if $\\|ru_\\theta(r,z,0)\\|_{L^\\infty}$ or $ \\|ru_\\theta(r,z,t)\\|_{L^\\infty(r\\leq r_0)}$ is small compared with certain dimensionless quantity of the initial data. This result improves the one in Zhen Lei and Qi S. Zhang \\cite{1}. As a corollary, we also prove the global regularity under the assumption that $|ru_\\theta(r,z,t)|\\leq\\ |\\ln r|^{-3/2},\\ \\ \\forall\\ 0