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-   -   Time Evolution of TKE (LES) (http://www.cfd-online.com/Forums/openfoam/86391-time-evolution-tke-les.html)

MaryBau March 21, 2011 18:37

Time Evolution of TKE (LES)
 
Hi All;

I am simulating decaying turbulence using a case very similar to the tutorial channelFoam/channel395. The only difference is that I have cyclic boundaries in all directions, so no walls.

I want to plot the time evolution of the averaged turbulence kinetic energy, but I am not sure how.

1. Are there any utilities already coded in OF to do this easily?

2. If not, how can I modify postChannel to get the TKE per time step for the whole domain, and not per region?

I tried modifying the function collapse() in channelIndexTemplate.C to returned the summedField instead of the regionField, but got wierd results.

Thanks, I appreciate your help!!

Mary

ozgur March 22, 2011 08:40

Hi,

If you are returning summedField instead of regionField you are still getting discrete values for different regions on the vertical line.

The only difference is that instead of getting the average values, you are getting the cumulative values of the fields, which are summed over discrete cell values. Therefore the values are still on region basis and also the cell value summation doesnot represent true integratation over those planes !

So, by an alternative loop maybe in an alternative function you may calculate and return the value of the overall field value integration which needs to be done by an algorithm like trapezoidal or simpson etc.


Özgür


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