[martyn88]

Hello all,

I am trying to simulate a supersonic turbulent free jet but am struggling to get a stable case running.

I think, as is often the case, the problem may lie in the boundary conditions.

Has anyone done a similar simulation that could perhaps advise me on appropriate boundary conditions?

My mesh is effectively a 1/8th section of a converging diverging nozzle surrounded by ambient fluid (atmospheric air)

Here are some images of my mesh:

meshpic.jpg

Foam mesh.jpg

inlet is the small leftmost face (nozzle inlet)
inlet 2 is the leftward facing face
nozzle wall is the horizontal face above inlet
freestream1 is the horizontal face just above the nozzle wall
freestream 2 is the large horizontal face on top
outlet is the rightward facing face
two side boundaries are cyclic AMI


My main concern is the outlet. Initially I defined just inlet, nozzle wall, cyclic boundaries and all other faces were outlet (inlet2, freestream1, freestream2 and outlet) but was unsure if it could handle multiple outlets.


I am using the rhoPimpleFoam solver and below are my 0 files:

FoamFile
{
version 2.0;
format ascii;
class volVectorField;
location "5e-05";
object U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions [0 1 -1 0 0 0 0];

internalField uniform (2 0 0);

boundaryField
{
inlet
{
type uniformFixedValue;
uniformValue table
(
(0 (10 0 0))
(0.08 (50 0 0))
(0.1 (50 0 0))
(0.3 (400 0 0))
);
}
inlet2
{
type uniformFixedValue;
uniformValue table
(
(0 (2 0 0))
(0.1 (2 0 0))
(0.4 (0 0 0))
);
}
outlet
{
type pressureInletOutletVelocity;
value uniform (2 0 0);
}
nozzlewall
{
type fixedValue;
value uniform (0 0 0);
}
face1
{
type cyclicAMI;
}
freestream1
{
type slip;
value uniform (0 0 0);
}
freestream2
{
type slip;
value uniform (0 0 0);
}
FaceGroup8
{
type cyclicAMI;
}
}


// ************************************************** *********************** //

FoamFile
{
version 2.0;
format ascii;
class volScalarField;
location "5e-05";
object T;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions [0 0 0 1 0 0 0];

internalField uniform 300;

boundaryField
{
inlet
{
type totalTemperature;
gamma 1.338;
phi phi;
psi psi;
T0 uniform 973;
value uniform 973;
}
inlet2
{
type zeroGradient;//totalTemperature
//gamma 1.338;
//phi phi;
//psi psi;
//T0 uniform 300;

}
outlet
{
type inletOutletTotalTemperature;
gamma 1.4;
T0 uniform 300;
value uniform 300;
}
nozzlewall
{
type fixedValue;
value uniform 300;
}
face1
{
type cyclicAMI;
}
freestream1
{
type zeroGradient;
}
freestream2
{
type zeroGradient;
}
FaceGroup8
{
type cyclicAMI;
}
}


// ************************************************** *********************** //

FoamFile
{
version 2.0;
format ascii;
class volScalarField;
location "5e-05";
object p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions [1 -1 -2 0 0 0 0];

internalField uniform 101325;

boundaryField
{
inlet
{
type zeroGradient;
}
inlet2
{
type zeroGradient;
}
outlet
{
type totalPressure;
rho rho;
psi none;
gamma 1.4;
p0 uniform 101325;
value uniform 101325;
}
nozzlewall
{
type zeroGradient;
}
face1
{
type cyclicAMI;
}
freestream1
{
type zeroGradient;
}
freestream2
{
type zeroGradient;
}
FaceGroup8
{
type cyclicAMI;
}
}


// ************************************************** *********************** //

FoamFile
{
version 2.0;
format ascii;
class volScalarField;
location "5e-05";
object muSgs;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions [1 -1 -1 0 0 0 0];

internalField uniform 0;

boundaryField
{
inlet
{
type calculated;
value uniform 0;
}
inlet2
{
type calculated;
value uniform 0;
}
outlet
{
type calculated;
value uniform 0;
}
nozzlewall
{
type muSgsUSpaldingWallFunction;
Cmu 0.09;
kappa 0.41;
E 9.8;
value uniform 0;
}
face1
{
type cyclicAMI;
}
freestream1
{
type calculated;
value uniform 0;
}
freestream2
{
type calculated;
value uniform 0;
}
FaceGroup8
{
type cyclicAMI;
}
}


// ************************************************** *********************** //

FoamFile
{
version 2.0;
format ascii;
class volScalarField;
location "5e-05";
object k;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions [0 2 -2 0 0 0 0];

internalField uniform 2e-05;

boundaryField
{
inlet
{
type fixedValue;
value uniform 2e-05;
}
inlet2
{
type zeroGradient;
}
outlet
{
type inletOutlet;
inletValue uniform 2e-05;
value uniform 2e-05;
}
nozzlewall
{
type compressible::kqRWallFunction;
value uniform 2e-05;
}
face1
{
type cyclicAMI;
}
freestream1
{
type zeroGradient;
}
freestream2
{
type zeroGradient;
}
FaceGroup8
{
type cyclicAMI;
}
}


// ************************************************** *********************** //

FoamFile
{
version 2.0;
format ascii;
class volTensorField;
location "5e-05";
object B;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions [0 2 -2 0 0 0 0];

internalField uniform (0 0 0 0 0 0 0 0 0);

boundaryField
{
inlet
{
type fixedValue;
value uniform (0 0 0 0 0 0 0 0 0);
}
inlet2
{
type fixedValue;
value uniform (0 0 0 0 0 0 0 0 0);
}
outlet
{
type inletOutlet;
inletValue uniform (0 0 0 0 0 0 0 0 0);
value uniform (0 0 0 0 0 0 0 0 0);
}
nozzlewall
{
type zeroGradient;
}
face1
{
type cyclicAMI;
}
freestream1
{
type zeroGradient;
}
freestream2
{
type zeroGradient;
}
FaceGroup8
{
type cyclicAMI;
}
}


// ************************************************** *********************** //

FoamFile
{
version 2.0;
format ascii;
class volScalarField;
location "5e-05";
object alphaSgs;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions [1 -1 -1 0 0 0 0];

internalField uniform 0;

boundaryField
{
inlet
{
type calculated;
value uniform 0;
}
inlet2
{
type calculated;
value uniform 0;
}
outlet
{
type calculated;
value uniform 0;
}
nozzlewall
{
type alphaSgsWallFunction;
Cmu 0.09;
kappa 0.41;
E 9.8;
value uniform 0;
}
face1
{
type cyclicAMI;
}
freestream1
{
type calculated;
value uniform 0;
}
freestream2
{
type calculated;
value uniform 0;
}
FaceGroup8
{
type cyclicAMI;
}
}


// ************************************************** *********************** //


Any help would be greatly appreciated.

Thankyou in advance