ANSYS CFX: Produce swirling flow using cylindrical components

neilduffy1024 · July 6, 2010, 10:49

Hi, I want to mimic swirling flow into a furnace using cylindrical components in the boundary conditions. I want to specify a mass flowrate followed by the flow direction. The axis of rotation will be specified as two points.

There is no decription in the user guides how the theta component is used. When selecting the cylindrical velocity components the units are for linear velocity, ie m/s etc, which obviously depends on the distance from the axis of rotation, yet there is no description in the user guides of how CFX accounts for this. Can the theta component be specified in terms of an angular velocity, ie radians/s, or as a linear velocity dependent on the distance from the axis of rotation, ie a velocity profile, perhaps using a CEL expression? If so, is there a simpler/more efficient method of describing this than through user Fortran?

Any help would be greatly appreciated.

Thanks,

Neil

magnusDux85 · June 4, 2013, 18:18

I have the same question. I want to mimic swirling flow in the injector.

ghorrocks · June 5, 2013, 07:02

Not sure if you can specify this using a rotating boundary coordinate system. Have a look and try it.

But it is easy to set this up as CEL expressions. A bit of maths to work out, that's all.

magnusDux85 · August 7, 2013, 08:52

Quote:

Originally Posted by ghorrocks

Not sure if you can specify this using a rotating boundary coordinate system. Have a look and try it.

But it is easy to set this up as CEL expressions. A bit of maths to work out, that's all.

Have you ever tried, could you give us some details?

ghorrocks · August 7, 2013, 09:00

No, never needed to do it so I have never done it.

But my second point is that it is easy to write it in the global coordinates, the transformation from cylindrical to global cartesian coords is pretty simple. So if it cannot be done in cylindrical coords then do it in global coords.

July 6, 2010, 10:49	ANSYS CFX: Produce swirling flow using cylindrical components	#1
neilduffy1024 Member Neil Duffy Join Date: Mar 2010 Posts: 34 Rep Power: 16	Hi, I want to mimic swirling flow into a furnace using cylindrical components in the boundary conditions. I want to specify a mass flowrate followed by the flow direction. The axis of rotation will be specified as two points. There is no decription in the user guides how the theta component is used. When selecting the cylindrical velocity components the units are for linear velocity, ie m/s etc, which obviously depends on the distance from the axis of rotation, yet there is no description in the user guides of how CFX accounts for this. Can the theta component be specified in terms of an angular velocity, ie radians/s, or as a linear velocity dependent on the distance from the axis of rotation, ie a velocity profile, perhaps using a CEL expression? If so, is there a simpler/more efficient method of describing this than through user Fortran? Any help would be greatly appreciated. Thanks, Neil Last edited by neilduffy1024; July 7, 2010 at 10:22.

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June 4, 2013, 18:18		#2
magnusDux85 Member Michal Join Date: Dec 2012 Posts: 39 Rep Power: 14	I have the same question. I want to mimic swirling flow in the injector.

June 5, 2013, 07:02		#3
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	Not sure if you can specify this using a rotating boundary coordinate system. Have a look and try it. But it is easy to set this up as CEL expressions. A bit of maths to work out, that's all.

August 7, 2013, 09:00		#5
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	No, never needed to do it so I have never done it. But my second point is that it is easy to write it in the global coordinates, the transformation from cylindrical to global cartesian coords is pretty simple. So if it cannot be done in cylindrical coords then do it in global coords.