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Pipe flow simulation problem with pisoFoam: not getting parabolic profile

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Old   September 7, 2016, 13:21
Default Pipe flow simulation problem with pisoFoam: not getting parabolic profile
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Sheikh Ahmed
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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
Attached Files
File Type: docx wedge.docx (132.0 KB, 15 views)
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Old   September 7, 2016, 15:00
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Sheikh Ahmed
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Any of your suggestion will be highly appreciated. Please share if you faced similar problems.

~SFA
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Tags
jet breakup, laminar flow, pipe flow, pisofoam, wedge type

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