## Fluids

#### Intial Gauge Pressure in Fluent

• PhillipEng
Subscriber

Guys i have one doubt about Gauge Pressure. For example, I'll start to try simulate a car and  i want to find Drag, but in the  boundary condition exist : Intlet Air and Outlet Air( this two names i put on).

Intlet Air there are two place to put data: Velocity Magnitude(m/s) and Supersonic/ Initial Gauge Pressure (Pa).

In  Velocity Magnitude(m/s) i put : 50 m/s and Supersonic/ Initial Gauge Pressure (Pa) = 0 Pa . With velocity data, it's still nescessary set on initial pressure Gauge ?

• José Mantovani
Subscriber

Hello Phillip,

I would recommend that you configure the inlet of domain as velocity-inlet and the outlet of the domain as a pressure-outlet. Adjust velocity as you prefer, in normal magnitude to boundary or in components. And generally for these cases an outlet pressure of Pout = 0 Pa is used. Make sure that the geometry surfaces of the car are configured as a wall.

I hope I've helped.

Best Regards,

Mantovani.

• Karthik R

Hello,

The Supersonic / Initial gauge pressure, as indicated by its name, is used to prescribe static pressure for supersonic flows. Here is a screenshot from Fluent Users Guide. I urge you to read more about this in the Users guide. Please also have a look at Initialization in the Fluent Theory Guide. I hope this helps.

Thank you.

Best Regards,

Karthik

• José Mantovani
Subscriber

Following what Kremella has explained, I can be sure that it is not the case of the flow through the car, even more so by the admitted velocity of 50 m / s, forming a subsonic and incompressible flow. Try what I said.

Hugs,

Mantovani.

• PhillipEng
Subscriber

Ty, guys for support. Now, I understand more about Initialization in Fluent, for this case.

• DrAmine
Ansys Employee

Just to add as general CFD hint:  only for supersonic flows we need to provide 5 B.C information on inflow boundaries instead of 4 for a subsonic case for a 3D case. On outlet B.C we do not need to provide anything for a supersonic flow where we require one information to be provided for subsonic flow.