Hi.

You can use tecplot for your post-processing. by means of tecplot, you can probe velocity fluctuations or turbulence kinetic energy in an arbitrary point. then, you can use FFT to get your energy spectrum. it gives you the results with respect to frequency. then you can change it into wave number or whatever you want.

hope it would be useful.

First, the theoretical inertial range k^-5/3 exists for particolar condition, that is in regions of the flow where turbulence can be assumed homogenous/isotropic. This law describes an energy cascade that happens like the flow were almost inviscid.

Therefore, you have to describe your flow problem as it not necessarily will show such behavior.

Then, be careful that a LES solution does not resolve up to the Kolmogorov scale. Your energy spectra extends only up to the grid cut-off (Nyquist) kc=pi/h.

The standard way to get an energy spectra is to perform the FFT of a velocity component and plot the modulus of the Fourier coefficients versus the wavenumbers (k=n*2*pi/L). You have to average the coefficients along the homogeneous directions.

Maybe I am worng, but I remember that some options for the statistics are present in FLuent. However, Matlab is suitable to do the statistical analysis.

Probably Dr Denise Hertwig ([email protected]) or Dr Nektarios Koutsourakis ([email protected]) can help you.

Reading my PoF paper might help you. 

Thank you all! The FFT idea works nicely enough on MATLAB, and even CFD-Post does a decent job, altough a bit too slow... Dr. Fang, I'll read your paper, still haven't had time to do it.