Lie Group Analysis, Direct Numerical Simulation and Wavelet Analysis of a Turbulent Channel Flow Rotating about the Streamwise Direction.
Technische Universität, Darmstadt
[Ph.D. Thesis], (2007)
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|Item Type:||Ph.D. Thesis|
|Title:||Lie Group Analysis, Direct Numerical Simulation and Wavelet Analysis of a Turbulent Channel Flow Rotating about the Streamwise Direction|
In this thesis turbulent channel flow with streamwise rotation has been investigated by means of an analytical and a numerical method. First investigations were done in 1998 by Oberlack employing the symmetry group theory. Oberlack showed that there is a new turbulent scaling law related to the turbulent channel flow rotating about the mean flow direction. The induction of a cross flow in the spanwise direction is the most obvious difference compared to the classical case, rotation about the spanwise direction. Established on these results the new scaling law was derived using Lie group analysis of the two-point correlation equations. Further it was shown that all six components of the Reynolds stress tensor are non-zero. To verify these effects a Direct Numerical Simulation was performed. The influence of the rotation was studied at three different Reynolds numbers (Re=180, 270 and 560) and at a variety of different rotation rates. Both the induced cross flow and the fact that the six components of the Reynolds stress tensor are non-zero could be verified. In addition a significant decay of the streamwise maximum velocity between Ro=5.2 and 10 was noticed. At the same time the cross flow reaches a maximum at about Ro=10 and then decreases for higher rotation rates. These observations are called 'rotation drag effect' (RDE). Furthermore a Wavelet analysis was performed to obtain more insight into the RDE and the corresponding structural effects. Therefore the Coherent Vortex Extraction (CVE) method was applied to six selected three-dimensional DNS data sets at Re=180. The compression rate as well as the enstrophy of the coherent vorticity component show a noticeable reverse between Ro=5.2 and 10. This tendency is supported by the skewness and the flatness of the coherent vorticity component. In general the results confirm a significant change in the flow dynamics.
|Place of Publication:||Darmstadt|
|Uncontrolled Keywords:||channel flow, fluid dynamics, wavelets, Lie group|
|Classification DDC:||600 Technik, Medizin, angewandte Wissenschaften > 620 Ingenieurwissenschaften|
|Divisions:||16 Department of Mechanical Engineering|
|Date Deposited:||17 Oct 2008 09:22|
|Last Modified:||07 Dec 2012 11:52|
|Referees:||Schäfer, Prof. Dr. Michael|
|Advisors:||Oberlack, Prof. Dr.- Martin|
|Refereed:||24 January 2007|