Time Accurate Unstructured Grid Adaption in Two and Three Dimensions

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dc.contributor.advisor Dr. D. Scott McRae, Committee Chair en_US
dc.contributor.advisor Dr. Jack R. Edwards, Committee Member en_US
dc.contributor.advisor Dr. Hassan A. Hassan, Committee Member en_US
dc.contributor.advisor Dr. C. T. Kelley, Committee Member en_US
dc.contributor.author Carpenter, James Givens, V en_US
dc.date.accessioned 2010-04-02T18:45:12Z
dc.date.available 2010-04-02T18:45:12Z
dc.date.issued 2007-12-07 en_US
dc.identifier.other etd-10222007-214317 en_US
dc.identifier.uri http://www.lib.ncsu.edu/resolver/1840.16/4115
dc.description.abstract The adaption algorithm of Benson et al is extended to three dimensional unstructured grids, building on the previous extension to two dimensional unstructured grids. R-refinement grid adaption is performed using a center of mass equation constructed from a weight function computed from solution gradients. Solution variables are updated using a coupled approach where the flux interface for each cell face is adjusted by the local grid velocity. Modifications to the integration scheme are incorporated to account for volume changes due to grid adaption through the introduction of an unsteady residual term which is resolved using sub-iterations at each timestep. The previous structured grid definition of grid velocity is shown to be inadequate for unstructured grid motion, and a new conservation based grid velocity equation is constructed from the local face displacement, which is designed to capture the volume change and preserve geometric conservation. Time accuracy is demonstrated for two and three dimensions using a shock tube simulation. Implementation for three dimensions is accomplished using a parallel, point implicit commercial flow solver. Incorporation of the gridspeed terms in the flux interface equations is presented along with the modifications to the implicit integration scheme required to account for the volume change as the grid is displaced. Extension to three dimensions required development of smoothing routines designed to preserve or recapture grid quality for arbitrary tetrahedral grids based on a geometric quality definition. A wing section under a prescribed sinusoidal motion is presented as a demonstration case to show the efficacy of the method. Computational results are compared to experimental data and solutions obtained using CFL3D. en_US
dc.rights I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dis sertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. en_US
dc.subject Conservative en_US
dc.subject Moving Grid en_US
dc.subject CFD en_US
dc.subject Geometric Conservation Law en_US
dc.title Time Accurate Unstructured Grid Adaption in Two and Three Dimensions en_US
dc.degree.name PhD en_US
dc.degree.level dissertation en_US
dc.degree.discipline Aerospace Engineering en_US


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