Learning Forum

[maria.marinari]

Hi Everyone,

I was wondering if anyone knew of a way of adding additional turbulence at an internal boundary. Either through a UDF or an extra boundary condition. The boundary in question already has a fan boundary condition on it, can you add additional boundary conditions to the same boundary?

If anyone has any ideas I would really appreciate it.

All the best,

Maria

[Rob]

Not at the surface boundary, but you can add "stuff" into cell zones using source terms. 

[maria.marinari]

Thanks so much would I do that using user-defined scalers?

[Rob]

You can, or just add more "turbulence".

[maria.marinari]

Ah, right I see. Is there a way to do this just on the cells at the boundary rather than everywhere in the domain?

[Rob]

Yes and no. There's no reason you can't split some cells to add the source too, so you add it to a whole zone which isn't the same as the whole model. Otherwise you need a UDF; expressions may also work but not sure where we've got re conditional source terms. 

[maria.marinari]

Could I then theoretically write a UDF That creates a cell zone from all the cells directly behind the faces on the boundary and add a source term to them?

[Rob]

Yes, you'd need to ID the surface, it's normal and then tag the cells. Check expressions too, you may be able to set

IF  15

ELSE source = 0.0

[maria.marinari]

Awesome thanks so much!

Where would I hook in a udf like that, do you know which macro should I use to base the udf off?

[Rob]

You'd need DEFINE_SOURCE https://ansyshelp.ansys.com/account/Secured?returnurl=/Views/Secured/corp/v221/en/flu_udf/flu_udf_sec_define_source.html

[maria.marinari]

Thanks so much for all your help!