Reynolds Stress model in CFX vs Fluent

December 6, 2005, 23:09

Hi.. I currently have access to both CFX & Fluent 6. I've done some simulation in CFX5.7.1 before and wish to compare the same model in Fluent. CFX5.7.1 has a range of Reynodls Stress Model:

1.SSG model developed by Speziale,Sarkar & Gatski,

2.LRR-IP (isotropisation for production) & -QI (Quasi-Isotropic) developed by Launder,Reece & Rodi

3.Baseline omega model

4.omega-Reynolds Stress model

From what I read from Fluent manual, Reynolds stress model used in Fluent 6 is developed by Gibson & Launder, Launder, and Launder et al.

Does anyone know if Fluent's RST model is the same as LRR-IP or LRR-QI used in CFX? I notice that in Fluent the constant Ce1=1.44,Ce2=1.92,C_mu=0.09 etc... whie in CFX the constant Ce1=1.45,Ce2=1.9,C_mu=0.1152 etc for LRR-IP... Are they the same model?

Thanks for your information. Cheers,Tim

ghorrocks · October 7, 2009, 07:19

I don't know the details of the RSM models, all I can suggest is you compare the constants and modelled equations and check they are the same.

Don't forget that the numerics of Fluent and CFX are very different so even if the model is the same it would not surprise me to get quite different results.

December 6, 2005, 23:09	Reynolds Stress model in CFX vs Fluent	#1
Tim Guest Posts: n/a	Hi.. I currently have access to both CFX & Fluent 6. I've done some simulation in CFX5.7.1 before and wish to compare the same model in Fluent. CFX5.7.1 has a range of Reynodls Stress Model: 1.SSG model developed by Speziale,Sarkar & Gatski, 2.LRR-IP (isotropisation for production) & -QI (Quasi-Isotropic) developed by Launder,Reece & Rodi 3.Baseline omega model 4.omega-Reynolds Stress model From what I read from Fluent manual, Reynolds stress model used in Fluent 6 is developed by Gibson & Launder, Launder, and Launder et al. Does anyone know if Fluent's RST model is the same as LRR-IP or LRR-QI used in CFX? I notice that in Fluent the constant Ce1=1.44,Ce2=1.92,C_mu=0.09 etc... whie in CFX the constant Ce1=1.45,Ce2=1.9,C_mu=0.1152 etc for LRR-IP... Are they the same model? Thanks for your information. Cheers,Tim

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October 7, 2009, 07:19		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	I don't know the details of the RSM models, all I can suggest is you compare the constants and modelled equations and check they are the same. Don't forget that the numerics of Fluent and CFX are very different so even if the model is the same it would not surprise me to get quite different results.