Week 11 - Simulation of Flow through a pipe in OpenFoam
Aim : To numerically validate the Hagen- Poiseuille's equation for the laminar flow through pipe.
Theory :
code of blockMeshDict file
/*--------------------------------*- C++ -*----------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 8
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
convertToMeters 1;
vertices
(
(0.00035 0 0) //0
(0.0007 0.0099 0) //1
(0 0.0099 0) //2
(0.00035 0 3) //3
(0.0007 0.0099 3) //4
(0 0.0099 3) //5
);
blocks
(
hex (0 1 2 0 3 4 5 3) (40 1 250) simpleGrading (0.1 1 1)
);
edges
(
);
boundary
(
inlet
{
type patch;
faces
(
(0 2 1 0)
);
}
outlet
{
type patch;
faces
(
(3 4 5 3)
);
}
upperWall
{
type wall;
faces
(
(1 2 5 4)
);
}
lowerWall
{
type wall;
faces
(
(0 3 3 0)
);
}
frontAndBack
{
type empty;
faces
(
(0 3 5 2)
(0 1 4 3)
);
}
);
mergePatchPairs
(
);
// ************************************************************************* //code of blockMeshDict file using Matlab
close all
clear all
clc;
l = 3;
d = 0.02;
r = d/2;
angle = 4;
alpha = angle/2;
f1 = fopen('blockMeshDict.txt','w');
fprintf(f1,'/*--------------------------------*- C++ -*----------------------------------*/\n');
fprintf(f1,' ========= |\n');
fprintf(f1,' \\ / F ield | OpenFOAM: The Open Source CFD Toolbox\n');
fprintf(f1,' \\ / O peration | Website: https://openfoam.org\n');
fprintf(f1,' \\ / A nd | Version: 8\n');
fprintf(f1,' \\/ M anipulation |\n');
fprintf(f1,'\*---------------------------------------------------------------------------*/\n');
fprintf(f1,'FoamFile\n');
fprintf(f1,'{\n');
fprintf(f1,' version 2.0;\n');
fprintf(f1,' format ascii;\n');
fprintf(f1,' class dictionary;\n');
fprintf(f1,' object blockMeshDict;\n');
fprintf(f1,'}\n');
fprintf(f1,'// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //\n');
fprintf(f1,'\nconvertToMeters 1;\n');
fprintf(f1,'\nvertices\n');
fprintf(f1,'(\n');
fprintf(f1,' (%f',r*sind(alpha));
fprintf(f1,' 0 0) //0 \n');
fprintf(f1,' (%f',2*r*sind(alpha));
fprintf(f1,' %f',r*cosd(alpha));
fprintf(f1,' 0) //1\n');
fprintf(f1,' (0');
fprintf(f1,' %f',r*cosd(alpha));
fprintf(f1,' 0) //2\n');
fprintf(f1,' (%f',r*sind(alpha));
fprintf(f1,' 0 %f',l);
fprintf(f1,') //3\n');
fprintf(f1,' (%f',2*r*sind(alpha));
fprintf(f1,' %f',r*cosd(alpha));
fprintf(f1,' %f',l);
fprintf(f1,'//4\n');
fprintf(f1,' (0 %f',r*cosd(alpha));
fprintf(f1,' %f',l);
fprintf(f1,'//5\n');
fprintf(f1,');\n');
fprintf(f1,'\nblocks\n');
fprintf(f1,'(\n');
fprintf(f1,' hex (0 1 2 0 3 4 5 3) (40 1 250) simpleGrading (0.1 1 1)\n');
fprintf(f1,');\n');
fprintf(f1,'\nedges\n');
fprintf(f1,'(\n');
fprintf(f1,');\n');
fprintf(f1,'\nboundary\n');
fprintf(f1,'(\n');
fprintf(f1,' inlet\n');
fprintf(f1,' {\n');
fprintf(f1,' type patch;\n');
fprintf(f1,' faces\n');
fprintf(f1,' (\n');
fprintf(f1,' (0 2 1 0)\n');
fprintf(f1,' );\n');
fprintf(f1,' }\n');
fprintf(f1,' outlet\n');
fprintf(f1,' {\n');
fprintf(f1,' type patch;\n');
fprintf(f1,' faces\n');
fprintf(f1,' (\n');
fprintf(f1,' (3 4 5 3)\n');
fprintf(f1,' );\n');
fprintf(f1,' }\n');
fprintf(f1,' upperWall\n');
fprintf(f1,' {\n');
fprintf(f1,' type wall;\n');
fprintf(f1,' faces\n');
fprintf(f1,' (\n');
fprintf(f1,' (1 2 5 4)\n');
fprintf(f1,' );\n');
fprintf(f1,' }\n');
fprintf(f1,' lowerWall\n');
fprintf(f1,' {\n');
fprintf(f1,' type wall;\n');
fprintf(f1,' faces\n');
fprintf(f1,' (\n');
fprintf(f1,' (0 3 3 0)\n');
fprintf(f1,' );\n');
fprintf(f1,' }\n');
fprintf(f1,' frontAndBack\n');
fprintf(f1,' {\n');
fprintf(f1,' type empty;\n');
fprintf(f1,' faces\n');
fprintf(f1,' (\n');
fprintf(f1,' (0 3 5 2)\n');
fprintf(f1,' (0 1 4 3)\n');
fprintf(f1,' );\n');
fprintf(f1,' }\n');
fprintf(f1,');\n');
fprintf(f1,'\nmergePatchPairs\n');
fprintf(f1,'(\n');
fprintf(f1,');\n');
fprintf(f1,'// ************************************************************************* //\n');
code of pressure file
/*--------------------------------*- C++ -*----------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 8
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
object p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 2 -2 0 0 0 0];
internalField uniform 0;
boundaryField
{
inlet
{
type zeroGradient;
}
outlet
{
type fixedValue;
value uniform 0.02008;
}
upperWall
{
type zeroGradient;
}
lowerWall
{
type zeroGradient;
}
frontAndBack
{
type empty;
}
}
// ************************************************************************* //code of velocity file
/*--------------------------------*- C++ -*----------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 8
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volVectorField;
object U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 1 -1 0 0 0 0];
internalField uniform (0 0 0);
boundaryField
{
inlet
{
type fixedValue;
value uniform (0 0 0.094);
}
outlet
{
type zeroGradient;
}
upperWall
{
type noSlip;
}
lowerWall
{
type noSlip;
}
frontAndBack
{
type empty;
}
}
// ************************************************************************* //code of controlDict file
dt = 0.01 sec
end time = length/avg velocity = 30 sec (approx.)
/*--------------------------------*- C++ -*----------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 8
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object controlDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
application icoFoam;
startFrom startTime;
startTime 0;
stopAt endTime;
endTime 30;
deltaT 0.01;
writeControl timeStep;
writeInterval 20;
purgeWrite 0;
writeFormat ascii;
writePrecision 6;
writeCompression off;
timeFormat general;
timePrecision 6;
runTimeModifiable true;
// ************************************************************************* //velocity profile at x = 0.2 m
velocity profile at x = 1 m
velocity profile at x = 2 m
velocity profile at x = 2.5 m
velocity profile at x = 2.8 m
fully developed velocity profile
pressure drop across the length
Shear-stress curve for pipe flow:
