Finally, we prove a blow up criterion for the full compressible Navier-Stokes equations just in terms of the gradient of the velocity. / In this thesis, the author study the blowup of solutions for strong and classical solutions to the compressible Navier-Stokes equations. In the first part, we prove a blow up criterion for strong solutions to the compressible Navier-Stokes equations, similar to the Beal-Kato-Majda criterion for the ideal incompressible flows. / The same criterion for classical solutions to the compressible Navier-Stokes equations is established in the second part of this thesis. In addition, initial vacuum is allowed in both cases. / Huang, Xiangdi. / Adviser: Zhouping Xin. / Source: Dissertation Abstracts International, Volume: 73-09(E), Section: B. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 90-96). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

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A numerical simulation of steady and unsteady two-dimensional flows past cylinder with dimples based on highly accurate pseudospectral method is the subject of the present thesis. The vorticity-streamfunction formulation of two-dimensional incompressible Navier-Stokes equations with no-slip boundary conditions is used. The system is formulated on a unit disk using curvilinear body fitted coordinate system. Key issues of the curvilinear coordinate transformation are discussed, to show its importance in properly defined node distribution. For the space discretization of the governing system the Fourier-Chebyshev pseudospectral approximation on a unit disk is implemented. To handle the singularity at the pole of the unit disk the approach of defining the computational grid proposed by Fornberg was implemented. Two algorithms for solving steady and unsteady problems are presented. For steady flow simulations the non-linear time-independent Navier-Stokes problem is solved using the Newton's method. For the time-dependent problem the semi-implicit third order Adams-Bashforth/Backward Differentiation scheme is used. In both algorithms the fully coupled system with two no-slip boundary conditions is solved. Finally numerical result for both steady and unsteady solvers are presented. A comparison of results for the smooth cylinder with those from other authors shows good agreement. Spectral accuracy is demonstrated using the steady solver. / February 2007

Paderborn, University, Fachb. Mathematik-Informatik, Diss. 1985.

Thèse de doctorat : Sciences : Mathématiques Appliquées : Toulon : 2002. / Thèse publiée sur le site TEL. Bibliographie p.243-247.

Thèse de doctorat : Sciences : Mathématiques Appliquées : Toulon : 2002. / Titre provenant du cadre-titre. Bibliographie p.243-247.

Thèse doctorat : Mécanique des fluides : La Rochelle : 2004. / Bibliogr. p. 223-229.

Thèse de doctorat : Mécanique et énergétique : INPL : 2008. / Titre provenant de l'écran-titre.

The first part of this thesis is devoted to a regularity criterion for solutions of the Incompressible Navier-Stokes equations in terms of regularity of the solutions along the streamlines. More precisely, we prove that we can ensure the full regularity of a given suitable weak solution provided we have good control on the second derivative of the velocity along the direction of the streamlines of the fluid. In the second part of this thesis, we will show that the global regularity of a suitable weak solution u for the incompressible Navier-Stokes equations holds under the condition that [mathematical equation] is integrable in space time variables. / text

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