[sahmed]

Dear Foamers
I am trying to simulate a simple 3D pipe flow with a wedge-shaped geometry using pisoFoam>ras>cavity solver. The reason I am using piso, not ico is that, I have to use another solver with chemical kinetics which uses Piso as its base flow solver. My flow is laminar with an inlet velocity of 0.1384 m/s, tube length 355mm, tube radius 42mm with a slanted part at the inlet (the geometry with the boundaries mentioned is attached with this post). Since my flow is laminar, in the constant>RASProperties.RASModel, I put 'laminar' with unchanged turbulenceProperties and transportProperties-

RASProperties:

FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "constant";
object RASProperties;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

RASModel laminar; //kEpsilon;

turbulence off;

printCoeffs off;


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

turbulenceProperties:

FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "constant";
object turbulenceProperties;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

simulationType RASModel;


transportProperties:

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

transportModel Newtonian;

nu nu [ 0 2 -1 0 0 0 0 ] 1e-05;

CrossPowerLawCoeffs
{
nu0 nu0 [ 0 2 -1 0 0 0 0 ] 1e-06;
nuInf nuInf [ 0 2 -1 0 0 0 0 ] 1e-06;
m m [ 0 0 1 0 0 0 0 ] 1;
n n [ 0 0 0 0 0 0 0 ] 1;
}

BirdCarreauCoeffs
{
nu0 nu0 [ 0 2 -1 0 0 0 0 ] 1e-06;
nuInf nuInf [ 0 2 -1 0 0 0 0 ] 1e-06;
k k [ 0 0 1 0 0 0 0 ] 0;
n n [ 0 0 0 0 0 0 0 ] 1;
}

Since I dont have turbulence, I didnt change any value of epsilon, k, nut and nuTilda in the 0 folder and I just put my pressure (P/rho) and velocity conditions-

FoamFile
{
version 2.0;
format ascii;
class volScalarField;
object p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField uniform 85654.5;

boundaryField
{
inlet
{
type zeroGradient;
}

outlet
{
type fixedValue;
value uniform 85654.5;
}

frontwall
{
type zeroGradient;
}

outerwall
{
type zeroGradient;
}

axisym_f1
{
type wedge;
}
axisym_f2
{
type wedge;
}
}


FoamFile
{
version 2.0;
format ascii;
class volVectorField;
object U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField uniform (0.01311 0 0);

boundaryField
{
inlet
{
type fixedValue;
value uniform (0.138475 0 0);
}

outlet
{
type zeroGradient;
}

frontwall
{
type fixedValue;
value uniform (0 0 0);
}

outerwall
{
type fixedValue;
value uniform (0 0 0);
}

axisym_f1
{
type wedge;
}
axisym_f2
{
type wedge;
}
}


My problem is, I am not getting a parabolic profile even after running for a longer time and the jet from the inlet is not breaking rather it is moving forward on and on. The recirculation bubble is also moving/stretching with the flow. This is definitely wrong.

Do you have any idea why this is happening? PLEASE share any of your experience of suggestion.
Thanks in advance

[sahmed]

Any of your suggestion will be highly appreciated. Please share if you faced similar problems.

~SFA