turbulent length scale

Tobi · June 3, 2013, 12:16

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

Thanks in advance.
Tobi

Henning86 · June 3, 2013, 12:24

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

turbulentMixingLengthDissipationRateInlet

you need the mixinglength 0.07.

Tobi · June 3, 2013, 12:34

Hi,

thanks for your reply.

I just wanted to know how to calculate 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.

abhishekramgadia · July 23, 2013, 06:22

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

Thanks in advance.

Tobi · July 23, 2013, 16:24

Hi,

http://www.cfd-online.com/Wiki/Turbulence_length_scale

abhishekramgadia · July 25, 2013, 02:01

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

UHGAR · October 12, 2016, 00:19

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

June 3, 2013, 12:16	turbulent length scale	#1
Tobi Super Moderator Tobias Holzmann Join Date: Oct 2010 Location: Bad Wörishofen Posts: 2,711 Blog Entries: 6 Rep Power: 52	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 Thanks in advance. Tobi

June 3, 2013, 12:24		#2
Henning86 Member Join Date: Nov 2012 Posts: 83 Rep Power: 13	i dont know for what you need it excatly but for this BC turbulentMixingLengthDissipationRateInlet you need the mixinglength 0.07. Tobi and anaspauzi like this.

June 3, 2013, 12:34		#3
Tobi Super Moderator Tobias Holzmann Join Date: Oct 2010 Location: Bad Wörishofen Posts: 2,711 Blog Entries: 6 Rep Power: 52	Hi, thanks for your reply. I just wanted to know how to calculate 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. Last edited by Tobi; April 23, 2019 at 06:38.

July 23, 2013, 06:22	Looking for Reference	#4
abhishekramgadia New Member Abhishek Ramgadia Join Date: May 2009 Posts: 3 Rep Power: 17	Can you please provide me a reference from where you got the equations: l = d_hyd * 0.038 l = d_hyd * 0.07 Thanks in advance. er99 likes this.

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July 23, 2013, 16:24		#5
Tobi Super Moderator Tobias Holzmann Join Date: Oct 2010 Location: Bad Wörishofen Posts: 2,711 Blog Entries: 6 Rep Power: 52	Hi, http://www.cfd-online.com/Wiki/Turbulence_length_scale

July 25, 2013, 02:01		#6
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October 12, 2016, 00:19		#7
UHGAR New Member UHGAR Join Date: Sep 2016 Posts: 12 Rep Power: 10	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