limited turbulent viscosity

December 21, 2004, 13:37

Hi all and happy hollidays: My problem is this : --Step 1: helium gas injection during 1 mn into a large cylinder filled with air at atmospheric pressure. The model is turbulent,compressible, time step 0.1 s. --Step 2: Stop helium injection and monitor helium equilibrium with air inside the cylinder during 250mn. During this step, along with the residuals , I monitor the average facelet velocity. For the fisrt few sconds , eveything was fine, afterwards, I have this message displayed : TURBULENT VISCOSITY LIMITED TO VISCOSITY RATIO OF 10E5. I changed the time step from 0.1s to 1s to 5s to 10s and I still have this message displayed. Am I doing something wrong, should the underrelaxation factor be pretty low or should I set an even bigger time step. Thanx for your help

December 26, 2004, 11:29

Hi,

Search the archive, there is quite a lot messages posted on this subject..

Regards,

Emre

December 21, 2004, 13:37	limited turbulent viscosity	#1
ahourri Guest Posts: n/a	Hi all and happy hollidays: My problem is this : --Step 1: helium gas injection during 1 mn into a large cylinder filled with air at atmospheric pressure. The model is turbulent,compressible, time step 0.1 s. --Step 2: Stop helium injection and monitor helium equilibrium with air inside the cylinder during 250mn. During this step, along with the residuals , I monitor the average facelet velocity. For the fisrt few sconds , eveything was fine, afterwards, I have this message displayed : TURBULENT VISCOSITY LIMITED TO VISCOSITY RATIO OF 10E5. I changed the time step from 0.1s to 1s to 5s to 10s and I still have this message displayed. Am I doing something wrong, should the underrelaxation factor be pretty low or should I set an even bigger time step. Thanx for your help

December 26, 2004, 11:29	Re: limited turbulent viscosity	#2
emre Guest Posts: n/a	Hi, Search the archive, there is quite a lot messages posted on this subject.. Regards, Emre

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