Orifice plate using rasInterFoam

gareth__it_power · March 19, 2009, 04:41

I'm trying to validate a simple orifice plate model for use in a larger assembly, but it is not behaving as I would expect. As you can see below the 'tail' from the orifice adheres to one side of the duct, rather than remaining symmetrical. Is this expected? Duct is 25mm wide, air, inlet velocity = 0.5m/s.

kev4573 · March 20, 2009, 15:31

This might be the Coanda effect at work, where a jet attaches itself to a boundary. There are papers out there that describe this phenomena.

kerstin · March 22, 2009, 08:26

Hi,
Is this result from steady state simulation?
Maybe transient run shows fluctuation of this tail up and down?
I would guess, that's not impossible for this kind of flow to show such a behaviour.
Kerstin

Linse · June 20, 2012, 09:41

Long time ago this has been. But I am experiencing something similar at the moment. The strange thing is: While using an incompressible solver, everything looks fine and qualitatively similar to ISO 5167-2 results.

But if I use rhoSimpleFoam instead of simpleFoam I get kind of two layers, one behaving normally in the outer half of the flow and something close to a jet in the middle half of the flow...

Any ideas concerning that?
Could you maybe tell which solver you used at that time, if it was compressible or incompressible, if you solved the "problem" or accepted the flow to be different from what one would have expected?

March 19, 2009, 04:41	Orifice plate using rasInterFoam	#1
gareth__it_power New Member Gareth Join Date: Mar 2009 Posts: 24 Rep Power: 17	I'm trying to validate a simple orifice plate model for use in a larger assembly, but it is not behaving as I would expect. As you can see below the 'tail' from the orifice adheres to one side of the duct, rather than remaining symmetrical. Is this expected? Duct is 25mm wide, air, inlet velocity = 0.5m/s.

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March 20, 2009, 15:31		#2
kev4573 Senior Member Kevin Smith Join Date: Mar 2009 Posts: 104 Rep Power: 17	This might be the Coanda effect at work, where a jet attaches itself to a boundary. There are papers out there that describe this phenomena.

March 22, 2009, 08:26		#3
kerstin New Member Kerstin Heinen Join Date: Mar 2009 Location: Ludwigshafen, Germany Posts: 27 Rep Power: 17	Hi, Is this result from steady state simulation? Maybe transient run shows fluctuation of this tail up and down? I would guess, that's not impossible for this kind of flow to show such a behaviour. Kerstin

June 20, 2012, 09:41		#4
Linse Senior Member Bernhard Linseisen Join Date: May 2010 Location: Heilbronn Posts: 183 Blog Entries: 1 Rep Power: 15	Long time ago this has been. But I am experiencing something similar at the moment. The strange thing is: While using an incompressible solver, everything looks fine and qualitatively similar to ISO 5167-2 results. But if I use rhoSimpleFoam instead of simpleFoam I get kind of two layers, one behaving normally in the outer half of the flow and something close to a jet in the middle half of the flow... Any ideas concerning that? Could you maybe tell which solver you used at that time, if it was compressible or incompressible, if you solved the "problem" or accepted the flow to be different from what one would have expected?