buoyant flow in a horizontal duct
 

hi,
I am trying to solve flow in a horizontal duct with inflow/outflow and constant temperature walls (top and bottom). I tried to solve it using buoyantPimpleFoam. I am not sure what I am doing wrong in my boundary conditions that give me unreasonable results.

I will appreciate any helpful comments.

my inlet BCs:

U:
inlet
{
type surfaceNormalFixedValue;
refValue uniform -0.01;
}

T:
inlet
{
type zeroGradient;
}

p:
inlet
{
type calculated;
value $internalField;
}

p_rgh:
inlet
{
type fixedValue;
value uniform 1e5;
}

For you temperature you should define an inlet temperature, you do have an temperature of the flow that comes in, don't you?

so for T inlet BC, I would suggest

Roman,
Thank you for reply.
I had already tested it with defined temperature and it would not help. The problem is I get reverse flow at inlet and also very large pressure inside the domain.
Now, I define p_rgh, T, and U as a constant value (at inlet), and still get a wrong answer.

Does anyone know what excatly the surfaceNormalFixedValue does at the inlet?
How can I learn the way openfoam handles boundary conditions?

Thank you,

inlet conditions and outlet conditions
 

Inlet conditions

U:
inlet
{
type fixedValue;
value uniform (1 0 0);
}

p_rgh:
inlet
{
type buoyantPressure;
rho rhok;
value uniform 1e5;
}
T:
inlet
{
type fixedValue;
value uniform 293;
}

outlet conditions

U:
outlet
{
type pressureInletOutletVelocity;
value uniform (0 0 0);
}

p_rgh:
{
type fixedValue;
rho rhok;
value uniform 1e5;
}

T:
outlet
{
type zeroGradient;
}

thanks Roman,
I tried this and worked well:

p_rgh:
-----------
inlet
{
type zeroGradient;
}

outlet
{
type fixedValue;
value uniform 1e5;
}

U:
--------
inlet
{
type surfaceNormalFixedValue;
refValue uniform -0.01;
}

outlet
{
type zeroGradient;
}

what does rho rhok; mean?

does it matter if use fixedValue instead of buoyantPressure for p_rgh at outlet?

thank you

buoyantPressure for p_rgh is also a zeroGradient boundary condition, but especially designed for buoyantFlows.

The description from OF for buoyantPressure is