[openfoam_user]

Dear OF-users,

I am simulating a water jet in air using interFoam. The simulation runs well.
To summarize my boundary conditions are:
For U
IN
{
type fixedValue;
value uniform (0 150 0);
OUT
{
type fixedValue;
value uniform (0 0 0);
}

ATMOSPHERE
{
type pressureInletOutletVelocity;
value uniform (0 0 0);
}

For p_rgh:
IN
{
type zeroGradient;
}

OUT
{
type zeroGradient;
}

ATMOSPHERE
{
type totalPressure;
p0 uniform 0;
U U;
phi phi;
rho rho;
psi none;
gamma 1;
value uniform 0;
}

My question is the following.
Is it also possible to impose a fixed pressure value at the inlet IN ?

Best regards,
Stephane.

[openfoam_user]

someone can help me ?
Stephane.

[ignacio]

Hello Stephane,

I think that in the boundaries OpenFOAM uses either pressure or velocity to compute the non-defined variable.
If you define velocity and pressure with fixedValue it will probably crash (at least in my case it does).

If you set the velocity to fixedValue at inlet, then pressure must be zeroGradient and then OpenFOAM will calculate it with the continuity equation.

Normally you would set

U
{
boundaryField
{
inlet
{
type fixedValue;
value uniform (0.76 0 0);
}

outlet
{
type inletOutlet;
inletValue uniform (0 0 0);
}
}
}


p
{
boundaryField
{
inlet
{
type zeroGradient;
}
outlet
{
type fixedValue;
value uniform 2.69e5;
}
}
}

Hope this helps

[openfoam_user]

Hi,
to summarize it is not possible to define both velocity and pressure for the inlet bc. OK. What is important for incompressible flows (channel flows) is the pressure variation.
Just to clarify, for my case, the bc OUT is not an outlet but a wall. It is a water jet into atmosphere with a vertical wall in front of the jet.
Regards,
Stephane.