Turbulent dissipation rate

Hello,

I have a spectral analysis plot with frequency (Hz) on x-axis and power spectral density ((cm/s)^2/Hz) on y-axis. My interest is to obtain the turbulent dissipation rate using Kolmogorov -5/3 law. I tried but I'm not sure on how to draw the -5/3 slope line on the log-log plot to find the inertial subrange. I have attached an excel sheet that shows the power spectrum data obtained from adv. Could someone please guide me on how to estimate the turbulent dissipation rate?

Please e-mail me at sudheer_2sudheer@yahoo.co.in

Thank you.

Ram

I'm collecting data in turbulent flow (open channel) with a sampling frequency of 30 Hz for 3 min. Does the turbulent dissipation rate estimate using Kolmogorov -5/3 law (Power spectrum) depends on sampling frequency and time ?

Ram

Hi Ram,

This is really more a fluid mechanics question, but I'll do my best to point you to a few references. Assuming the data came from a Nortek Vectrino or Vector, you could actually download the trial version of ExploreV and take a look at the help files included. I think they have a decent explanation of this process. The free software WinADV might also allow you to do this and have a good help file.

You can also take a look at the following reference (and references cited there): http://www.nortek-as.com/lib/bibliography/turbulent-dissipation-estimates-from-pulse-coherent-doppler-instruments

I'd also recommend taking a look at one of the classic texts on turbulence such as Tennekes and Lumley, A First Course in Turbulence or Davidson's Turbulence: An Introduction for Scientists and Engineers.

P.J.