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-   -   turbulent length scale (https://www.cfd-online.com/Forums/openfoam/118733-turbulent-length-scale.html)

 Tobi June 3, 2013 11:16

turbulent length scale

Hi all,

its a very simple question!

Is the turbulence length-scale in OpenFOAM based on the mixing-length ?

Its due to the fact of estimation of l

l = d_hyd * 0.038
l = d_hyd * 0.07

I am not 100% sure what to use.
In the past I thought that OF uses only the length-scale so I used always 0.038

Tobi

 Henning86 June 3, 2013 11:24

i dont know for what you need it excatly but for this BC

turbulentMixingLengthDissipationRateInlet

you need the mixinglength 0.07.

 Tobi June 3, 2013 11:34

Hi,

I just wanted to know how to calculate the the length scale for the cfd-online calculator:

http://www.cfd-online.com/Tools/turbulence.php

But thanks for your replay. So I think I need to set up the mixingLength (0.07) for the omega BC too.

Looking for Reference

Can you please provide me a reference from where you got the equations:
l = d_hyd * 0.038
l = d_hyd * 0.07

 Tobi July 23, 2013 15:24

Thanks Tobi,
I am looking for a literature (text book / journal paper) reference and not a web-page reference.

 UHGAR October 11, 2016 23:19

Hi, Foamers!

Can I get your valuable suggestions?
I would like to track the Turbulent length scales at every time step and at a particular location in flow field, and use it in paraFoam as well in quantitative post processing. How can I do it?

How the length scales field will be created just like u,p, k etc., ?

My main intention of doing this is, I wanted to compare my simulation jet (modeled by RANS) turbulent length scales with experimentally measured length scales.

Thanks,
UHGAR

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