BlockMesh Drill Down Challenge flow through Cavity
Intention:For the following diagram, with the use of icoFOAM solver , simulate the flow through a backward facing step.
The geometry shown above is created by five blocks using OpenFoam.It could have been created using three blocks too,but to capture results in a better way,it is created through 5 blocks.
##For Grading factor 0.2
- Number of cells along the x direction (longer dimension) = 200
- Number of cells along the y direction = 10
#BlockMeshDict File:
/*--------------------------------*- C++ -*----------------------------------*\\
========= |
\\\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\\\ / O peration | Website: https://openfoam.org
\\\\ / A nd | Version: 7
\\\\/ M anipulation |
\\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
convertToMeters 0.01;
vertices
(
(0 0 0)
(8 0 0)
(8 0.5 0)
(0 0.5 0)
(0 0 0.1)
(8 0 0.1)
(8 0.5 0.1)
(0 0.5 0.1)
(8 1 0)
(0 1 0)
(8 1 0.1)
(0 1 0.1)
(20 0.5 0)
(20 1 0)
(20 0.5 0.1)
(20 1 0.1)
(20 0 0)
(20 0 0.1)
(20 -1 0)
(8 -1 0)
(20 -1 0.1)
(8 -1 0.1)
);
blocks
(
hex (0 1 2 3 4 5 6 7) (200 10 1) simpleGrading (1 5 1)
hex (3 2 8 9 7 6 10 11) (200 10 1) simpleGrading (1 0.2 1)
hex (2 12 13 8 6 14 15 10) (200 10 1) simpleGrading (5 0.2 1)
hex (1 16 12 2 5 17 14 6) (200 10 1) simpleGrading (5 5 1)
hex (19 18 16 1 21 20 17 5) (200 10 1) simpleGrading (5 5 1)
)
;
edges
(
);
boundary
(
inlet
{
type patch;
faces
(
(3 7 11 9)
(0 4 7 3)
);
}
outlet
{
type patch;
faces
(
(14 12 13 15)
(17 16 12 14)
(20 18 16 17)
);
}
frontAndBack
{
type empty;
faces
(
(2 3 9 8)
(7 6 10 11)
(12 2 8 13)
(14 15 10 6)
(1 0 3 2)
(5 6 7 4)
(16 1 2 12)
(17 14 6 5)
(18 19 1 16)
(20 17 5 21)
);
}
fixedWalls
{
type wall;
faces
(
(10 8 9 11)
(15 13 8 10)
(1 5 4 0)
(18 20 21 19)
(19 21 5 1)
);
}
);
mergePatchPairs
(
);
// ************************************************************************* //#ControlDict file:
/*--------------------------------*- C++ -*----------------------------------*\\
========= |
\\\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\\\ / O peration | Website: https://openfoam.org
\\\\ / A nd | Version: 7
\\\\/ M anipulation |
\\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location \"system\";
object controlDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
application icoFoam;
startFrom startTime;
startTime 0;
stopAt endTime;
endTime 0.6;
deltaT 0.00001;
writeControl timeStep;
writeInterval 20;
purgeWrite 0;
writeFormat ascii;
writePrecision 6;
writeCompression off;
timeFormat general;
timePrecision 6;
runTimeModifiable true;
// ************************************************************************* //#Velocity Boundary Condition File:
/*--------------------------------*- C++ -*----------------------------------*\\
========= |
\\\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\\\ / O peration | Website: https://openfoam.org
\\\\ / A nd | Version: 7
\\\\/ 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 (1 0 0);
}
outlet
{
type zeroGradient;
}
fixedWalls
{
type noSlip;
value uniform (0 0 0);
}
frontAndBack
{
type empty;
}
}
// ************************************************************************* //#Pressure Boundary Condition file:
/*--------------------------------*- C++ -*----------------------------------*\\
========= |
\\\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\\\ / O peration | Website: https://openfoam.org
\\\\ / A nd | Version: 7
\\\\/ 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;
}
fixedWalls
{
type zeroGradient;
}
frontAndBack
{
type empty;
}
}
// ************************************************************************* //-------------------**************************************************************************************----------------------
##For Grading factor 0.5:
#BlockMeshdict file:
/*--------------------------------*- C++ -*----------------------------------*\\
========= |
\\\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\\\ / O peration | Website: https://openfoam.org
\\\\ / A nd | Version: 7
\\\\/ M anipulation |
\\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
convertToMeters 0.01;
vertices
(
(0 0 0)
(8 0 0)
(8 0.5 0)
(0 0.5 0)
(0 0 0.1)
(8 0 0.1)
(8 0.5 0.1)
(0 0.5 0.1)
(8 1 0)
(0 1 0)
(8 1 0.1)
(0 1 0.1)
(20 0.5 0)
(20 1 0)
(20 0.5 0.1)
(20 1 0.1)
(20 0 0)
(20 0 0.1)
(20 -1 0)
(8 -1 0)
(20 -1 0.1)
(8 -1 0.1)
);
blocks
(
hex (0 1 2 3 4 5 6 7) (200 10 1) simpleGrading (1 2 1)
hex (3 2 8 9 7 6 10 11) (200 10 1) simpleGrading (1 0.5 1)
hex (2 12 13 8 6 14 15 10) (200 10 1) simpleGrading (2 0.5 1)
hex (1 16 12 2 5 17 14 6) (200 10 1) simpleGrading (2 2 1)
hex (19 18 16 1 21 20 17 5) (200 10 1) simpleGrading (2 2 1)
)
;
edges
(
);
boundary
(
inlet
{
type patch;
faces
(
(3 7 11 9)
(0 4 7 3)
);
}
outlet
{
type patch;
faces
(
(14 12 13 15)
(17 16 12 14)
(20 18 16 17)
);
}
frontAndBack
{
type empty;
faces
(
(2 3 9 8)
(7 6 10 11)
(12 2 8 13)
(14 15 10 6)
(1 0 3 2)
(5 6 7 4)
(16 1 2 12)
(17 14 6 5)
(18 19 1 16)
(20 17 5 21)
);
}
fixedWalls
{
type wall;
faces
(
(10 8 9 11)
(15 13 8 10)
(1 5 4 0)
(18 20 21 19)
(19 21 5 1)
);
}
);
mergePatchPairs
(
);
// ************************************************************************* //----------------*****************************************************************************************---------------------
##For Grading factor 0.8:
#BlockMeshdict file:
/*--------------------------------*- C++ -*----------------------------------*\\
========= |
\\\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\\\ / O peration | Website: https://openfoam.org
\\\\ / A nd | Version: 7
\\\\/ M anipulation |
\\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
convertToMeters 0.01;
vertices
(
(0 0 0)
(8 0 0)
(8 0.5 0)
(0 0.5 0)
(0 0 0.1)
(8 0 0.1)
(8 0.5 0.1)
(0 0.5 0.1)
(8 1 0)
(0 1 0)
(8 1 0.1)
(0 1 0.1)
(20 0.5 0)
(20 1 0)
(20 0.5 0.1)
(20 1 0.1)
(20 0 0)
(20 0 0.1)
(20 -1 0)
(8 -1 0)
(20 -1 0.1)
(8 -1 0.1)
);
blocks
(
hex (0 1 2 3 4 5 6 7) (200 10 1) simpleGrading (1 1.25 1)
hex (3 2 8 9 7 6 10 11) (200 10 1) simpleGrading (1 0.8 1)
hex (2 12 13 8 6 14 15 10) (200 10 1) simpleGrading (1.25 0.8 1)
hex (1 16 12 2 5 17 14 6) (200 10 1) simpleGrading (1.25 1.25 1)
hex (19 18 16 1 21 20 17 5) (200 10 1) simpleGrading (1.25 1.25 1)
)
;
edges
(
);
boundary
(
inlet
{
type patch;
faces
(
(3 7 11 9)
(0 4 7 3)
);
}
outlet
{
type patch;
faces
(
(14 12 13 15)
(17 16 12 14)
(20 18 16 17)
);
}
frontAndBack
{
type empty;
faces
(
(2 3 9 8)
(7 6 10 11)
(12 2 8 13)
(14 15 10 6)
(1 0 3 2)
(5 6 7 4)
(16 1 2 12)
(17 14 6 5)
(18 19 1 16)
(20 17 5 21)
);
}
fixedWalls
{
type wall;
faces
(
(10 8 9 11)
(15 13 8 10)
(1 5 4 0)
(18 20 21 19)
(19 21 5 1)
);
}
);
mergePatchPairs
(
);
// ************************************************************************* //##For different grading factor,results shows some changes in velocity values.As finer mesh will give better,more accurate results,so where we want to know velocity value,mesh size should be kept finer near that region.
Like from results at 0.085m in x direction and 0m in y direction:
For 0.2 grading factor ,Velocity =0.62066 m/s
For 0.5 grading factor ,Velocity =0.62868 m/s
For 0.8 grading factor ,Velocity =0.63442 m/s