Implement swirl as "internal" BC with calculated u_axial

lentschi · October 27, 2011, 04:18

Hello everyone,

as you can see in the attched pdf-file, I want to calculate the case as follows:

A diffuser is determined in a water volume, the "global BCs" are the Velocity u=2m/s (Inlet) and p=0bar (Outlet). Now I want to implement a "swirl" as additional interior BC at an interface with the velocities (in cylindric coordinates) v_radial=1m/s and v_theta=0.8m/s, though v_axial should be the calculated u at this mentonoid interface!!
In fluent and OF it is possible to arranged that. But is this possible in CFX 13 too?And how can I implement it??

Thanks in advance.

Regards

lentschi · October 27, 2011, 04:49

Sorry, I forget the pdf....

ghorrocks · October 27, 2011, 06:13

Sounds like this should just be a momentum source term. Look it up in the documentation.

lentschi · October 28, 2011, 07:16

Hello,

thank you for your reply but there establish some problems with the momentum sources:

1) this is only for subdomains, not to use for Interfaces/BC (maybe I have overlook/missunderstood something)
2) I need velocities, not momentums

Regards

ghorrocks · October 28, 2011, 15:49

To fix 1 you just make the entire domain a subdomain. But the second part of your question is the crux of the problem, I cannot think of a way to make it act only at the interface and in the correct direction.

Question 2 is fine, a momentum source can specify velocities. The "momentum" refers to what equation it applies to, not what is applied.

lentschi · November 2, 2011, 02:53

OK,thank you for your answer!

Regards

bhatiadinesh · November 2, 2011, 04:58

Are you trying to simulate something which actually physically exists ? if, yes, what is the actual arrangement there ?

October 27, 2011, 04:18	Implement swirl as "internal" BC with calculated u_axial	#1
lentschi Member sirLentschi Join Date: Nov 2010 Posts: 80 Rep Power: 15	Hello everyone, as you can see in the attched pdf-file, I want to calculate the case as follows: A diffuser is determined in a water volume, the "global BCs" are the Velocity u=2m/s (Inlet) and p=0bar (Outlet). Now I want to implement a "swirl" as additional interior BC at an interface with the velocities (in cylindric coordinates) v_radial=1m/s and v_theta=0.8m/s, though v_axial should be the calculated u at this mentonoid interface!! In fluent and OF it is possible to arranged that. But is this possible in CFX 13 too?And how can I implement it?? Thanks in advance. Regards Last edited by lentschi; October 27, 2011 at 04:47.

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October 27, 2011, 06:13		#3
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	Sounds like this should just be a momentum source term. Look it up in the documentation.

October 28, 2011, 07:16		#4
lentschi Member sirLentschi Join Date: Nov 2010 Posts: 80 Rep Power: 15	Hello, thank you for your reply but there establish some problems with the momentum sources: 1) this is only for subdomains, not to use for Interfaces/BC (maybe I have overlook/missunderstood something) 2) I need velocities, not momentums Regards

October 28, 2011, 15:49		#5
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	To fix 1 you just make the entire domain a subdomain. But the second part of your question is the crux of the problem, I cannot think of a way to make it act only at the interface and in the correct direction. Question 2 is fine, a momentum source can specify velocities. The "momentum" refers to what equation it applies to, not what is applied.

November 2, 2011, 02:53		#6
lentschi Member sirLentschi Join Date: Nov 2010 Posts: 80 Rep Power: 15	OK,thank you for your answer! Regards

November 2, 2011, 04:58		#7
bhatiadinesh Member D Join Date: Nov 2010 Posts: 50 Rep Power: 15	Are you trying to simulate something which actually physically exists ? if, yes, what is the actual arrangement there ?