Turbulence Calculation

Simon_CFD · May 26, 2015, 09:07

Hello,

at the inlet there is the turbulent inlet boundary condition.

Now I like to calculate/measure the intensity at L/4, L/2, 3L/4 and L (L = length of the pipe).

Could you give me a tip?

Thank you!

Nicole · May 27, 2015, 06:41

Hi Simon,

Do you know what equation you would like to use to calculate the turbulence intensity? I remember looking for it a while back but I could not figure out exactly what OpenFOAM uses. I am by no means a turbulence expert, but if you have an equation for it then I might be able to help you implement that in OpenFOAM. Have you looked at the sample utility? I have not used it myself yet.

Regards,
Nicole

Blanco · May 30, 2015, 12:36

Hello,
it really depends on what kind of turbulence modelling you are using. If you are using rans equations then you can choose different turbulence models, as k-eps, k-omega, etc. If you have k available in your turb model then you can calculate turb intensity by deriving if from k value, because k is turbulence kinetic energy and it's directly linkend to turb intensity.
You can sample the k value where you want using the "sample" utility with a sampleDict.
If otherwise you are doing Les, you have turb components of velocities, therefore you can directly calculate turb intensity.

Best

May 26, 2015, 09:07	Turbulence Calculation	#1
Simon_CFD New Member Join Date: May 2015 Posts: 1 Rep Power: 0	Hello, at the inlet there is the turbulent inlet boundary condition. Now I like to calculate/measure the intensity at L/4, L/2, 3L/4 and L (L = length of the pipe). Could you give me a tip? Thank you!

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May 27, 2015, 06:41		#2
Nicole Member Nicole Andrew Join Date: Sep 2014 Location: Pretoria, South Africa Posts: 58 Rep Power: 11	Hi Simon, Do you know what equation you would like to use to calculate the turbulence intensity? I remember looking for it a while back but I could not figure out exactly what OpenFOAM uses. I am by no means a turbulence expert, but if you have an equation for it then I might be able to help you implement that in OpenFOAM. Have you looked at the sample utility? I have not used it myself yet. Regards, Nicole

May 30, 2015, 12:36		#3
Blanco Senior Member Blanco Join Date: Mar 2009 Location: Torino, Italy Posts: 193 Rep Power: 17	Hello, it really depends on what kind of turbulence modelling you are using. If you are using rans equations then you can choose different turbulence models, as k-eps, k-omega, etc. If you have k available in your turb model then you can calculate turb intensity by deriving if from k value, because k is turbulence kinetic energy and it's directly linkend to turb intensity. You can sample the k value where you want using the "sample" utility with a sampleDict. If otherwise you are doing Les, you have turb components of velocities, therefore you can directly calculate turb intensity. Best