CFX Streamline Curvature Correction model

flow.pratish · May 28, 2010, 03:32

CFX 12.0 has got a streamline curvature correction model. Also, it provides few parameteric tuning into it, such as CSCALE. When to use this model ? and what shall be the range of values for CSALE ? Would be greatfull if someone tells about why its to be used ..

ghorrocks · May 28, 2010, 08:47

It is to correct turbulence generation in strongly swirling flows. Don't fiddle with the constants unless you REALLY know what you are doing, and certainly not before reading the literature about what the constants mean.

flow.pratish · May 28, 2010, 08:52

Thanks Glenn for the reply. Exactly the same flow i am trying to simulate which has strong swirls in it. However, the solution shows intense variation as I change the parameter CSCALE value over small ranges ....

flow.pratish · May 28, 2010, 08:59

even in smaller range of values for CSCALE, such as, 1, 1.5 and 2.0, the solution varies immensly. The CFX Solver theory guide do not talk about any guidance on it. They do not suggest any range for it. For how much intense swirl flow what value of cscale one shall belive on ? no idea. Secondly, if the sreamline curvature correction model does take care of the curvature effect due to swirl flow then why shall we need the cscale ?

ghorrocks · May 28, 2010, 09:07

Quote:

The CFX Solver theory guide do not talk about any guidance on it.

As I said, there should be a literature reference for the model in the documentation. You won't get anywhere until you follow that up. Do not fiddle with the constants until you know what they mean.

Whether you need the curvature correction model or not is up to you. Run with it and without it and see if it makes a difference to your models. Also keep in mind that other turbulence models may be more appropriate such as RSM or LES. 2-equation turbulence models are well known to have problems with strongly swirling flows.

flow.pratish · May 28, 2010, 09:59

yes Glenn, i googled through the CFX document for streamline curvature correction model, which pointed to Literature article by Spalart & Shur.
I checked with the article as well, surprisingly, the original model as in the article does not talk about any scaling factor as such.

ghorrocks · May 29, 2010, 08:10

You would have to talk to CFX support for more detailed information about this model then.

hesamking · August 29, 2012, 16:44

I am simulating blood flow in an artery and my streamlines doesn't start from inlet and their shape is swirling instead of straight through the artery (pipe). do u have any idea what the problem can be?
I have attached the pic
thanks,

ghorrocks · August 29, 2012, 19:32

Your image is unreadable.

But the problem is going to be in your setup, or it is not fully converged.

Please do not hijack threads. For a new question start a new thread.

May 28, 2010, 03:32	CFX Streamline Curvature Correction model	#1
flow.pratish New Member Join Date: May 2010 Posts: 4 Rep Power: 0	CFX 12.0 has got a streamline curvature correction model. Also, it provides few parameteric tuning into it, such as CSCALE. When to use this model ? and what shall be the range of values for CSALE ? Would be greatfull if someone tells about why its to be used ..

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May 28, 2010, 08:47		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	It is to correct turbulence generation in strongly swirling flows. Don't fiddle with the constants unless you REALLY know what you are doing, and certainly not before reading the literature about what the constants mean.

May 28, 2010, 08:52		#3
flow.pratish New Member Join Date: May 2010 Posts: 4 Rep Power: 0	Thanks Glenn for the reply. Exactly the same flow i am trying to simulate which has strong swirls in it. However, the solution shows intense variation as I change the parameter CSCALE value over small ranges ....

May 28, 2010, 08:59		#4
flow.pratish New Member Join Date: May 2010 Posts: 4 Rep Power: 0	even in smaller range of values for CSCALE, such as, 1, 1.5 and 2.0, the solution varies immensly. The CFX Solver theory guide do not talk about any guidance on it. They do not suggest any range for it. For how much intense swirl flow what value of cscale one shall belive on ? no idea. Secondly, if the sreamline curvature correction model does take care of the curvature effect due to swirl flow then why shall we need the cscale ?

May 28, 2010, 09:59		#6
flow.pratish New Member Join Date: May 2010 Posts: 4 Rep Power: 0	yes Glenn, i googled through the CFX document for streamline curvature correction model, which pointed to Literature article by Spalart & Shur. I checked with the article as well, surprisingly, the original model as in the article does not talk about any scaling factor as such.

May 29, 2010, 08:10		#7
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	You would have to talk to CFX support for more detailed information about this model then.

August 29, 2012, 19:32		#9
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	Your image is unreadable. But the problem is going to be in your setup, or it is not fully converged. Please do not hijack threads. For a new question start a new thread.