Turbulence modelling in OpenFoam

nore5 · February 14, 2013, 11:22

Hello,

I find some difficulties defining the right parameters related to turbulence modelling in OpenFoam. in fact, I tried to follow the same steps available in the user guide to set a turbulence model but the result is always the same, my simulations /when I set up a case from scratch/ crash with very high bounding values of turbulence parameters after the first time steps.

How can I learn how to set up an accurate turbulence model please? I can t find a tutorial that focuses on that in particular / a part from user guide/...

Any advice and guidelines are welcome too.

Thanks in advance.

Nore

Lieven · February 14, 2013, 13:38

Hi Nore,

Are you using RANS or LES?

Often this type of crash is caused by a bad initial condition or/and by (incompatible) boundary conditions. One 'trick' that can help obtaining better initial conditions is by running potentialFoam first for a number of time steps...

Cheers,

L

chegdan · February 14, 2013, 16:31

For RANS-based simulations ( and you're sure your boundary conditions are correct), in addition to potentialFoam as an initial condition you can:

Use upwind schemes to start with
Run the turbulent case with the laminar model first, then turn on turbulence mid simulation
use the converged first order result as an initial condition for higher order schemes

These are just some quick tips.

nore5 · February 15, 2013, 15:04

Dan and Lieven thank you for these hints.

I will try to apply it to a case and see what happens.

BUT how to make sure the BC are the right ones too please?

Thanks again.

February 14, 2013, 11:22	Turbulence modelling in OpenFoam	#1
nore5 New Member Join Date: Jan 2013 Posts: 20 Rep Power: 13	Hello, I find some difficulties defining the right parameters related to turbulence modelling in OpenFoam. in fact, I tried to follow the same steps available in the user guide to set a turbulence model but the result is always the same, my simulations /when I set up a case from scratch/ crash with very high bounding values of turbulence parameters after the first time steps. How can I learn how to set up an accurate turbulence model please? I can t find a tutorial that focuses on that in particular / a part from user guide/... Any advice and guidelines are welcome too. Thanks in advance. Nore

February 14, 2013, 16:31		#3
chegdan Senior Member Daniel P. Combest Join Date: Mar 2009 Location: St. Louis, USA Posts: 621 Rep Power: 0	For RANS-based simulations ( and you're sure your boundary conditions are correct), in addition to potentialFoam as an initial condition you can: Use upwind schemes to start with Run the turbulent case with the laminar model first, then turn on turbulence mid simulation use the converged first order result as an initial condition for higher order schemes These are just some quick tips.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
OpenFOAM: LES turbulence model names	Ollie	OpenFOAM	5	January 7, 2013 11:24
OpenFOAM: LES turbulence model names	Ollie	Main CFD Forum	1	April 11, 2011 14:03
Homogeneous Turbulence Modelling	Zaktatir	CFX	0	December 15, 2010 10:37
Recompile turbulence model in OpenFoam	qtian	OpenFOAM Running, Solving & CFD	7	November 26, 2007 16:51
modelling transition with v2f turbulence model	pablo	FLUENT	0	August 7, 2006 16:44

February 14, 2013, 13:38		#2
Lieven Senior Member Lieven Join Date: Dec 2011 Location: Leuven, Belgium Posts: 299 Rep Power: 23	Hi Nore, Are you using RANS or LES? Often this type of crash is caused by a bad initial condition or/and by (incompatible) boundary conditions. One 'trick' that can help obtaining better initial conditions is by running potentialFoam first for a number of time steps... Cheers, L

February 15, 2013, 15:04		#4
nore5 New Member Join Date: Jan 2013 Posts: 20 Rep Power: 13	Dan and Lieven thank you for these hints. I will try to apply it to a case and see what happens. BUT how to make sure the BC are the right ones too please? Thanks again.