multi-turbulence model

turbotel · July 11, 2011, 07:20

hi,

I'm simulating rotating machinery problem.
inlet is mass-flow & temperature.
outlet is static pressure.
after solving (SST - is my turbulence) predicted inlet pressure is 32% more than test data.
what's is the problem?

for this i plan to choose some other turbulence model for stationary (ex. volute..) domains and SST for rotating domain only.
Is that good idea first?

pl somebody help me.
thank you

ghorrocks · July 11, 2011, 19:08

http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F

Abou ali · July 13, 2011, 12:17

Hi,
First, you have to verify your machine dimensions especially the inlet and outlet areas then do a mesh sensitivity study, finaly try to obtain an Ypls less than 2 near the walls if you are using SST model.

turbotel · July 14, 2011, 06:36

hi ali,
what is " check machine dimensions especially the inlet and outlet areas"
Pl explain.
thank you

ghorrocks · July 14, 2011, 07:52

He means check that your geometry matches the experiment. Other than that all his comments (and much more detail) are mentioned on the FAQ link I referenced.

turbotel · July 14, 2011, 07:56

ok.
I have not done any changes in CAD model. it's same as test model.
and now i'm trying to find out my discretization error.
thank for your info.

July 11, 2011, 07:20	multi-turbulence model	#1
turbotel New Member Join Date: Nov 2010 Posts: 26 Rep Power: 15	hi, I'm simulating rotating machinery problem. inlet is mass-flow & temperature. outlet is static pressure. after solving (SST - is my turbulence) predicted inlet pressure is 32% more than test data. what's is the problem? for this i plan to choose some other turbulence model for stationary (ex. volute..) domains and SST for rotating domain only. Is that good idea first? pl somebody help me. thank you

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July 11, 2011, 19:08		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,692 Rep Power: 143	http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F

July 13, 2011, 12:17		#3
Abou ali Member Join Date: Nov 2009 Posts: 49 Rep Power: 16	Hi, First, you have to verify your machine dimensions especially the inlet and outlet areas then do a mesh sensitivity study, finaly try to obtain an Ypls less than 2 near the walls if you are using SST model.

July 14, 2011, 06:36		#4
turbotel New Member Join Date: Nov 2010 Posts: 26 Rep Power: 15	hi ali, what is " check machine dimensions especially the inlet and outlet areas" Pl explain. thank you

July 14, 2011, 07:52		#5
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,692 Rep Power: 143	He means check that your geometry matches the experiment. Other than that all his comments (and much more detail) are mentioned on the FAQ link I referenced.

July 14, 2011, 07:56		#6
turbotel New Member Join Date: Nov 2010 Posts: 26 Rep Power: 15	ok. I have not done any changes in CAD model. it's same as test model. and now i'm trying to find out my discretization error. thank for your info.