000032411 001__ 32411
000032411 005__ 20180501105756.0
000032411 0247_ $$2doi$$a10.5075/epfl-thesis-1934
000032411 02471 $$2nebis$$a3864682
000032411 037__ $$aTHESIS_LIB 000032411 041__$$aeng
000032411 088__ $$a1934 000032411 245__$$aNumerical study of transitions in Taylor-Couette flow
000032411 260__ $$aLausanne$$bEPFL$$c1999 000032411 269__$$a1999
000032411 300__ $$a170 000032411 336__$$aTheses
000032411 502__ $$aAlbin Boelcs, Georges Labrosse, Peter Monkewitz, Ernest Mund, Alfio Quarteroni, Brian Smith 000032411 520__$$aThis thesis is divided into two parts. In the first one       the creation of a complete numerical tool, from the mesh       generation to the data treatment, is presented. However time       consuming this part has been, this is not the most important       one. The second and more important part is concerned with the       description and physical interpretation of the results       obtained with the numerical tool previously developed.  The numerical tool, which exists in its quasi-final         version since mid-1997, fully satisfies the following         requirements. It is specifically designed to study the flow         in the annular space between coaxial,         differentially-rotating cylinders of finite length. The         spectral element method is used for the space         discretization. The study of transition requires the high         accuracy warranted by this type of method. The numerical         scheme has also to be efficient. This requirement is         satisfied, due to the fully-explicit time scheme adopted,         where both diffusive and non-linear terms of the         Navier-Stokes equations are treated explicitly, and the         direct inversion of the pseudo-Laplacian matrix applied to         the pressure. This inversion is performed in the most         efficient way with a fast diagonalization technique. In the         Reynolds numbers range we are interested in, the time-step         limitation due to the linear viscous term is only slightly         more stringent than the one due to the non-linear term. The         last requirement that has been fulfilled has been to design         as simple a code as possible.         The entire code is constructed from a number of well-known         algorithms, fitted together to enhance efficiency. However,         the way we regularize the boundary conditions is new. It         represents the physics more precisely than Tavener et         al. [65]. There is a second original feature in our         code, which is linked to the time scheme. We derived our         time discretization from the scheme of Gavrilakis et         al. [31]. Their scheme cannot be applied to cylindrical         coordinates as it is. We thus had to modify it. The second part of the thesis consists of the numerical         study of the first transitions of the Taylor-Couette flow         in a finite-length geometry. The aspect ratio between the         length of the cylinders and the gap between them has been         chosen equal to twelve; this is small enough for the         effects of the upper and lower boundaries of the flow to be         significant. It is believed that these end-effects play a         non-negligible role in the transition of the flow. On the         other hand, the aspect ratio is large enough to make         qualitative comparisons with the infinite-length case,         which has been studied extensively both theoretically and         numerically. The transition process depends on a relatively         large number of parameters. Our investigation focuses on         the case where the cylinders rotate in opposite directions.         The study of counter-rotating Taylor-Couette flow for a         large but finite aspect ratio is the main originality of         this thesis. Furthermore, the physical mechanism of the         appearance of the second bifurcation in classical         Taylor-Couette flow, where only the inner cylinder is         rotating, is described in the light of the non-linear         interaction between velocity and vorticity.
000032411 700__ $$0(EPFLAUTH)105728$$aMagère, Eric$$g105728 000032411 720_2$$0240906$$aDeville, Michel$$edir.$$g104955 000032411 8564_$$s6547594$$uhttps://infoscience.epfl.ch/record/32411/files/EPFL_TH1934.pdf$$yTexte intégral / Full text$$zTexte intégral / Full text 000032411 909C0$$0252047$$pLIN$$xU10316
000032411 909CO $$ooai:infoscience.tind.io:32411$$pDOI2$$pDOI$$pthesis
000032411 918__ $$aSTI$$cIGM
000032411 919__ $$aLIN 000032411 920__$$a1999-10-1$$b1999 000032411 970__$$a1934/THESES
000032411 973__ $$aEPFL$$sPUBLISHED
000032411 980__ aTHESIS