Cylindrical Components Boundary Conditions

magnusDux85 · August 8, 2013, 07:02

Do somebody can give clear instruction how understand cylindrical components from ANSYS point of view? Are they unit vectors or what?

I want to mimic swirling flow in injector of combustion chamber.

ghorrocks · August 8, 2013, 08:03

I do not understand what you are asking. Cylindrical coords for what? A local coord system? Or a 2D axisymmetric simulation? And what are you modelling in your injector - the flow inside the injector, the spray it creates or a combustion model?

magnusDux85 · August 8, 2013, 08:06

Cylindrical comp. of flow direction as a result I want to have fuel well mixed with oxygen.

ghorrocks · August 8, 2013, 08:09

I still do not understand what you are asking. Have you completed a simulation and you want to extract the velocity of something in cylindrical corrds? If so what is something?

magnusDux85 · August 8, 2013, 08:14

Please have a look:

http://postimg.org/image/4rqo0p3dt/ injector is modeled in this case as a point source...

ghorrocks · August 8, 2013, 08:20

I assume you are asking what form the cylindrical coords are. Yes, they are unit vectors. But I think you can enter any vector and CFX will take them as unit vectors anyway.

magnusDux85 · August 8, 2013, 08:24

You are right, I was asking about it thx.

magnusDux85 · August 8, 2013, 08:32

But how check influence of these components on swirling properties in the simplest way?

magnusDux85 · August 8, 2013, 13:38

Very difficult to predict

.

magnusDux85 · August 8, 2013, 14:16

To do the topic more understandable I have attached image:

ghorrocks · August 8, 2013, 18:47

Your image was not attached and your question is still not clear.

But if you are asking how can you assess the importance of the direction vector on your simulation - you can do this with a simple sensitivity analysis. Just run a series of simulations with different direction vectors and compare the results. If there is no significant change in the result then the direction vector makes little difference.

magnusDux85 · August 9, 2013, 02:45

Quote:

Originally Posted by ghorrocks

Your image was not attached and your question is still not clear.

But if you are asking how can you assess the importance of the direction vector on your simulation - you can do this with a simple sensitivity analysis. Just run a series of simulations with different direction vectors and compare the results. If there is no significant change in the result then the direction vector makes little difference.

Thank you know it is: http://postimg.org/image/hj4w0kz45/

mirabella · August 11, 2013, 18:26

Hello

I am facing the same issue. I want to generate a certain swirl in an axisymmetric slice section of a burner chamber. The question is then here, how is the flow direction related to the swirl strength and to the flow pattern?
Therefore, I need first of all to know the exact definition of theta component?

August 8, 2013, 07:02	Cylindrical Components Boundary Conditions	#1
magnusDux85 Member Michal Join Date: Dec 2012 Posts: 39 Rep Power: 13	Do somebody can give clear instruction how understand cylindrical components from ANSYS point of view? Are they unit vectors or what? I want to mimic swirling flow in injector of combustion chamber.

August 11, 2013, 18:26	swirl modeling	#13
mirabella New Member mira Join Date: Jun 2011 Posts: 6 Rep Power: 14	Hello I am facing the same issue. I want to generate a certain swirl in an axisymmetric slice section of a burner chamber. The question is then here, how is the flow direction related to the swirl strength and to the flow pattern? Therefore, I need first of all to know the exact definition of theta component?

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August 8, 2013, 08:03		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,701 Rep Power: 143	I do not understand what you are asking. Cylindrical coords for what? A local coord system? Or a 2D axisymmetric simulation? And what are you modelling in your injector - the flow inside the injector, the spray it creates or a combustion model?

August 8, 2013, 08:06		#3
magnusDux85 Member Michal Join Date: Dec 2012 Posts: 39 Rep Power: 13	Cylindrical comp. of flow direction as a result I want to have fuel well mixed with oxygen.

August 8, 2013, 08:09		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,701 Rep Power: 143	I still do not understand what you are asking. Have you completed a simulation and you want to extract the velocity of something in cylindrical corrds? If so what is something?

August 8, 2013, 08:14		#5
magnusDux85 Member Michal Join Date: Dec 2012 Posts: 39 Rep Power: 13	Please have a look: http://postimg.org/image/4rqo0p3dt/ injector is modeled in this case as a point source...

August 8, 2013, 08:20		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,701 Rep Power: 143	I assume you are asking what form the cylindrical coords are. Yes, they are unit vectors. But I think you can enter any vector and CFX will take them as unit vectors anyway.

August 8, 2013, 08:24		#7
magnusDux85 Member Michal Join Date: Dec 2012 Posts: 39 Rep Power: 13	You are right, I was asking about it thx.

August 8, 2013, 08:32		#8
magnusDux85 Member Michal Join Date: Dec 2012 Posts: 39 Rep Power: 13	But how check influence of these components on swirling properties in the simplest way?

August 8, 2013, 13:38		#9
magnusDux85 Member Michal Join Date: Dec 2012 Posts: 39 Rep Power: 13	Very difficult to predict .

August 8, 2013, 14:16		#10
magnusDux85 Member Michal Join Date: Dec 2012 Posts: 39 Rep Power: 13	To do the topic more understandable I have attached image:

August 8, 2013, 18:47		#11
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,701 Rep Power: 143	Your image was not attached and your question is still not clear. But if you are asking how can you assess the importance of the direction vector on your simulation - you can do this with a simple sensitivity analysis. Just run a series of simulations with different direction vectors and compare the results. If there is no significant change in the result then the direction vector makes little difference.