Learning Forum

[Max4]

Hi,

I want to set a static pressure as boundary condition at the inlet of a system.

In the FLUENT User´s Guide I have found this:

Is there any tricks in order to set a static pressure at the inlet?

Regards,

Maxime

 

[DrAmine]

You need a UDF to adjust the total pressure so that it results in the desired static pressure. All inflow quantities are total quantities. 

[Max4]

Thanks for the reply.

What should such a function look like?

Should I use a DEFINE_PROFILE macro ?

Regards,

Maxime

[Rob]

Yes, you're wanting DEFINE_PROFILE. 

[DrAmine]

The only possible hook is the DEFINE_PROFILE to set the total pressure as sum of the desired value for static pressure+ dynamic part (if compressible flow then an isentropic relationship between stagnation With the new Fluent Expression you can do that with some relaxation without any UDF.

[Max4]

Hi,

Thanks for your answers.

The problem is that I have a transient flow (compressible flow) and the velocity at the inlet is varying. So it´s not possible to set the total pressure as sum of the desired value.

Is there any solution to set a constant static pressure for transient flow?

Regards,

Maxime

[Max4]

Is it possible to reverse the inlet and outlet in order to be able to put a static pressure at the real inlet (outlet2)? At the inlet2 can I set a negative value for mass flow rate or velocity in order to models an exit (=outlet)?

[Rob]

You can use a negative mass flow: just change the vector direction.