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-   -   Averaging LES (http://www.cfd-online.com/Forums/fluent/48648-averaging-les.html)

 iko July 1, 2008 14:55

Averaging LES

I'm runnning and LES simulation, and I want to do an averaging of the mean velocity and rms. And as you know for an LES solution, time-averaged data can only be derived by data-sampling and processing. For my first simulation I stored multiple data sets from LES solutions and then compute averaging of several samples (for mean and rms velocity) with matlab and tecplot. As ou imagine it was a tedious task. So I'm thinking now that instead of storing multiple data sets, it is most efficient to define the data-processing up front and execute it on-the-fly.

I'd like to know how I can set the Sampling Interval such that Data Sampling for Time Statistics can be performed at the specified frequency? My timestep is 0.2 ms, and my integral time scale is about 20ms. I need a sampling interval of 20 ms, which mean every 100 time step ( 100*0.2=20ms) How can I set the sampling Interval? And is it possible to compute the averaging with fluent (averaging with at least 35 samples) ?

Sincerely

 arkur July 1, 2008 18:23

Re: Averaging LES

Fluent should do it for you. You need to do any averaging at all.

 iko July 1, 2008 18:35

Re: Averaging LES

I know fluent is able to do it,

but the question is : how can I set the Sampling Interval?

 Paolo Lampitella July 3, 2008 05:55

Re: Averaging LES

In the iterate panel, under options, enable "Data Sampling for Time Statistics" and choose your sampling interval, that is "How many time steps do you want it is going to be?"

It's just there; after that the unsteady statistics will be automatically available under "display-contours"

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