Difficulty in setting a udf periodic boundary condition
 

Hello,

I am running a simulation over a fin, I have two options either to give periodic boundary condition with user defined pressure jump, given by:

P(x,y,z)=−βx+p(x,y,z)

Here, β is the linear component of the pressure and p(x,y,z) is periodic pressure component. β=(Pressure inlet-pressure outlet)/fin length.

My second option is to map the simulation data from outlet and initialize it as an inlet to achieve a fully developed flow condition. Can someone help me with this ?

What does any of this this have to do with a UDF? Btw, we are in Star correct?

All you have to do is select the two boundaries, right click, and create the periodic interface. In physics values Star doesn't let you specify Beta, you have to specify the pressure jump, which is Beta x periodic length. You could do more work and create custom functions or parameters that would convert Beta to a pressure jump if you needed to automate.

Thank you for the response. Yes, I am using STAR. I don't have the exact pressure jump value, I tried creating a custom function but was unable to do so. It is showing an error stating that, the expression for pressure jump (name of the function I created) cannot be solved for pressure jump. I guess the periodic length that I defined was wrong. Hence the error, I am trying to define the periodic length. I would really appreciate if you can help me with this. Thank you.

You are free to vent your frustrations if that's all you're looking for =)


If you want help with an error, maybe post details about the error you are dealing with... Start by dumping your expression.