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-   -   Spectral methods need help - Poiseuille flow (http://www.cfd-online.com/Forums/main/72457-spectral-methods-need-help-poiseuille-flow.html)

vetnav February 5, 2010 14:51

Spectral methods need help - Poiseuille flow
 
Hello folks,

I am using a spectral code to carry out linear stability analysis, I validated the code for the plane Poiseuille flow for Re = 10000 and wave number = 1 (the case in Hydrodynamic stability by Drazin 1981, p. no 221-223) and obtained similar distribution of eigen values and c= 0.2375+0.0037i but there seems to be a problem with my imaginary part of eigen function distribution.
As I am using MATLAB, the eigen function is calculated by MATLAB built in functions so why only imaginary part of eigen function is not varying as it should in the book??

Secondly, I did the calculations for production term and it is positive with a peak near the wall this is as per the books theory as on p.no. 425, so even when I am not getting a proper imaginary part of eigen function I end up getting proper Reynolds stress distribution and production.

Also I need help in calculating vorticity from this eigen functions, I did the calculations but when I plot them though I can see that the boundary layer is unstable vortex loops are aligning to one side.

Thank you


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