[Peter88]

Hi,

I am busy for a test case using buoyantBoussinesqPimpleFOAM.
It is case with natural convection. The 2D geometry exist out of a square domain, with in the middle a cilinder. The cilinder has a temperature of 400K and the surrounding field has a temperature of 300K. I made the sides and bottom pressure inlets and the top a pressure outlet. I used buoyantBoussinesqPimpleFoam, because the case is lightly compressible and transient. When I am post processing the case I see that the heat that is rising is instable. Some kind of velocity waves comes in the domain from the outside. This is probably due to not matching density with my boundary temperature, or something. Any body ideas? How can I fix this? Define a rhoInf? How?

I will put my boundary conditions below, to see what I have done.

Alphat:
{
p_out
{
type zeroGradient;
}

p_in
{
type zeroGradient;
}

sym_back
{
type empty;
}

sym_front
{
type empty;
}

wall
{
type alphatWallFunction;
value uniform 0;
}
}

Epsilon:
{
p_out
{
type zeroGradient;
}
p_in
{
type zeroGradient;
}
sym_back
{
type empty;
}
sym_front
{
type empty;
}
wall
{
type epsilonWallFunction;
Cmu 0.09;
kappa 0.41;
E 9.8;
value uniform 0.01;
}
}

K:

internalField uniform 0.1;

boundaryField
{
p_out
{
type zeroGradient;
}
p_in
{
type zeroGradient;
}
sym_back
{
type empty;
}
sym_front
{
type empty;
}
wall
{
type kqRWallFunction;
value uniform 0.1;
}
}

Kappat:

internalField uniform 0;

boundaryField
{
p_out
{
type zeroGradient;
}

p_in
{
type zeroGradient;
}

sym_back
{
type empty;
}

sym_front
{
type empty;
}

wall
{
type kappatJayatillekeWallFunction;
Prt 0.85;
value uniform 0;
}
}

P:
internalField uniform 1e5;

boundaryField
{
p_out
{
type calculated;
value $internalField;
}

p_in
{
type calculated;
value $internalField;
}

sym_back
{
type empty;
}

sym_front
{
type empty;
}

wall
{
type calculated;
value $internalField;
}
}

p_rgh:


internalField uniform 1e5;

boundaryField
{
p_out
{
type buoyantPressure;
value uniform 1e5;
}

p_in
{
type buoyantPressure;
value uniform 1e5;
}

sym_back
{
type empty;
}

sym_front
{
type empty;
}

wall
{
type buoyantPressure;
value uniform 1e5;
}
}

T:

internalField uniform 300;

boundaryField
{
p_out
{
type zeroGradient;
}

p_in
{
type fixedValue;
value uniform 300;
}

sym_back
{
type empty;
}

sym_front
{
type empty;
}

wall
{
type fixedValue;
value uniform 400;
}
}

U:
internalField uniform (0 0 0);

boundaryField
{
p_out
{
type zeroGradient;
}
p_in
{
type pressureInletVelocity;
value uniform (0 0 0);
}
sym_back
{
type empty;
}
sym_front
{
type empty;
}
wall
{
type fixedValue;
value uniform (0 0 0);
}
}

I hope somebody can help me out. I can send the case file to email or something.

With kind regards

Peter Rupert