[jonior]

in boundary condition i want to ask about if i have an opening (not pressure in or out) just opening i want from the simulation to predict if the flow will goes out from it or it will be like a vacuum ??? which boundary condition should i use in fluent (note: in CFX boundary condition has a type called opening i didn't found the same in fluent)

[jonior]

pls did any one know the answer my simulation is stopped bcz i couldn't adjust it

[marauder]

I think 'Outflow' boundary condition should help. But a better explanation of problem would be good to decide.

[jonior]

no, i cannot use outflow bcz i am modeling a compressible flow t t the socend outle

in my problem i have 4 pressure inlets and 2 outlets for air one of them i know that the pressure will goes out from it but the second outlet i dont know if the pressure will goes out or will be reversed to goes out from the first out let

[marauder]

Originally Posted by jonior

In my problem i have 4 pressure inlets and 2 outlets for air one of them i know that the pressure will goes out from it but the second outlet i dont know if the pressure will goes out or will be reversed to goes out from the first out let

Then outlets will be pressure oulets with the pressure at outlet to be specified.

[jamalf64]

Hi dear friend
I think you can use symmetry boundary condition. Its Ok.

[pakk]

Originally Posted by jamalf64

Hi dear friend
I think you can use symmetry boundary condition. Its Ok.

Don't do this. A symmetry boundary condition will block flow, so it is not ok.

If you don't know if it is an inlet or an outlet, I would start by assuming it is an outlet. Select the "pressure outlet" boundary condition, and apply the pressure on the outside of your inlet/outlet.

Then do your simulation until it converges. You might see messages like "20 faces in surface 40 have reversed flow" (I don't remember the exact phrasing), this means your "outlet" is really an inlet (or at least partially). Once your simulation has converged, look at the solution. If your "outlet" has fluid coming into the system, your guess was wrong. In that case, change it into an inlet.

[stuart23]

If it is a compressible simulation, you should be using pressure far-field

Stu

[jonior]

thanks for all. i am trying in inlet and outlet

but i don't know about far-field could you explain more.

[maryam74121]

hi every one
im simulating a kind of micro chamber which has 4 vents for air it means that this boundry can be inlet and outlet simultaneously just for air and it shouldnt pass phase 2 (water) across itself.which boundry i can use?
my simulation is vof and transient
im glad to hear from you
tnx