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-   -   Implement swirl as "internal" BC with calculated u_axial (https://www.cfd-online.com/Forums/cfx/93811-implement-swirl-internal-bc-calculated-u_axial.html)

 lentschi October 27, 2011 04:18

Implement swirl as "internal" BC with calculated u_axial

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??

Regards

 lentschi October 27, 2011 04:49

1 Attachment(s)
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 03:53