18 September 2015 2 867 Report

As a phD researcher, I am trying to validate my solver through use of decaying isotropic turbulence. I preferred to use the Wray1997 data, which would be a good step towards evaluating my solver's performance. However, I am confused with the setup of the benchmark case. The data is not very informative because it is an unpublished set of data. The main issue i came across is the nondimensionalization. in the Wray data, the time starts at 1.0045, which i suppose dimensional time in seconds. don't know why it starts at 1.0045, though, maybe referring to the Re=100.45.. So if it is dimensionless, what are the parameters to nondimensionalize? They could be eddy turnover time, integral length scale, taylor scale and rms velocity. But they all change in time! Additionally, in the wray data the viscosity is given as 3.5014006E-4. is it dimensional kinematic viscosity? Another question to raise is about the given initial field. I developed a Matlab code to obtain the 3-D energy spectrum from the given field. it works fine, except it does not catch the exact magnitude of the 512^3 data's given spectrum, where my spectrum looks like an earlier stage (see the attached figure). The question is, is the given field somewhat an earlier state than the Re=100.45 initial spectrum or my code has a mistake somehow? 

You can also see in the figure my result assuming every given thing is dimensional

Thanks in advance

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