Week 8 - BlockMesh Drill down challenge
- Mesh Specifications:
- Number of cells along the x-direction (longer dimension) = 200
- Number of cells along the y-direction = 10
- Grading factor near all walls - 0.2
- A smaller grading factor produces a more uniform mesh.
f = (size of end cell) / (size of starting cell)
- Boundary Condition Specification:
- Block:
- Steps for Simulation
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 0.01;
vertices
(
(0 0 0) //Vertex number 0
(8 0 0) //Vertex number 1
(8 0.5 0) //Vertex number 2
(0 0.5 0) //Vertex number 3
(8 1 0) //Vertex number 4
(0 1 0) //Vertex number 5
(20 1 0) //Vertex number 6
(20 0.5 0) //Vertex number 7
(20 0 0) //Vertex number 8
(20 -1 0) //Vertex number 9
(8 -1 0) //Vertex number 10
(0 0 0.1) //Vertex number 11
(8 0 0.1) //Vertex number 12
(8 0.5 0.1) //Vertex number 13
(0 0.5 0.1) //Vertex number 14
(8 1 0.1) //Vertex number 15
(0 1 0.1) //Vertex number 16
(20 1 0.1) //Vertex number 17
(20 0.5 0.1) //Vertex number 18
(20 0 0.1) //Vertex number 19
(20 -1 0.1) //Vertex number 20
(8 -1 0.1) //Vertex number 21
);
blocks
(
hex (0 1 2 3 11 12 13 14) (200 10 1) simpleGrading (1 1 1)
hex (3 2 4 5 14 13 15 16) (200 10 1) simpleGrading (1 1 1)
hex (2 7 6 4 13 18 17 15) (200 10 1) simpleGrading (1 1 1)
hex (1 8 7 2 12 19 18 13) (200 10 1) simpleGrading (1 1 1)
hex (10 9 8 1 21 20 19 12) (200 10 1) simpleGrading (1 1 1)
);
edges
(
);
boundary
(
inlet
{
type patch;
faces
(
(0 11 14 3)
(3 14 16 5)
);
}
outlet
{
type patch;
faces
(
(9 8 19 20)
(8 7 18 19)
(7 6 17 18)
);
}
frontAndBack
{
type empty;
faces
(
(0 3 2 1)
(3 5 4 2)
(10 1 8 9)
(1 2 7 8)
(2 4 6 7)
(11 12 13 14)
(14 13 15 16)
(21 20 19 12)
(12 19 18 13)
(13 18 17 15)
);
}
noslipwalls
{
type wall;
faces
(
(5 16 15 4)
(4 15 17 6)
(0 1 12 11)
(10 21 12 1)
(10 9 20 21)
);
}
);
mergePatchPairs
(
);
// ************************************************************************* //
ControlDict 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;
location "system";
object controlDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
application icoFoam;
startFrom startTime;
startTime 0;
stopAt endTime;
endTime 0.25;
deltaT 1e-5;
writeControl timeStep;
writeInterval 100;
purgeWrite 0;
writeFormat ascii;
writePrecision 6;
writeCompression off;
timeFormat general;
timePrecision 6;
runTimeModifiable true;
// ************************************************************************* //VolScalarField- Pressure Boundary Conditions 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 1 -1 0 0 0 0];
internalField uniform (0 0 0);
boundaryField
{
inlet
{
type fixedValue;
value uniform (1 0 0);
}
outlet
{
type zeroGradient;
}
frontAndBack
{
type empty;
}
noslipwalls
{
type noSlip;
}
}
// ************************************************************************* //Pressure:
/*--------------------------------*- 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;
}
frontAndBack
{
type empty;
}
noslipwalls
{
type zeroGradient;
}
}
// ************************************************************************* //For Grading Scheme 1
hex (0 1 2 3 11 12 13 14) (200 10 1) simpleGrading (1 1 1)
hex (3 2 4 5 14 13 15 16) (200 10 1) simpleGrading (1 1 1)
hex (2 7 6 4 13 18 17 15) (200 10 1) simpleGrading (1 1 1)
hex (1 8 7 2 12 19 18 13) (200 10 1) simpleGrading (1 1 1)
hex (10 9 8 1 21 20 19 12) (200 10 1) simpleGrading (1 1 1)
Velocity without Surface Edges
Velocity with Surface Edges
U Magnitude Plot
For Grading Scheme 0.2
hex (0 1 2 3 11 12 13 14) (200 10 1) simpleGrading (0.2 1.2 1)
hex (3 2 4 5 14 13 15 16) (200 10 1) simpleGrading (0.2 0.2 1)
hex (2 7 6 4 13 18 17 15) (200 10 1) simpleGrading (1.2 0.2 1)
hex (1 8 7 2 12 19 18 13) (200 10 1) simpleGrading (1.2 1.2 1)
hex (10 9 8 1 21 20 19 12) (200 10 1) simpleGrading (1.2 1.2 1)
U without Surface Edges
U with Surface Edges
U Magnitude Plot
For Grading Scheme 0.5
hex (0 1 2 3 11 12 13 14) (200 10 1) simpleGrading (0.5 1.5 1)
hex (3 2 4 5 14 13 15 16) (200 10 1) simpleGrading (0.5 0.5 1)
hex (2 7 6 4 13 18 17 15) (200 10 1) simpleGrading (1.5 0.5 1)
hex (1 8 7 2 12 19 18 13) (200 10 1) simpleGrading (1.5 1.5 1)
hex (10 9 8 1 21 20 19 12) (200 10 1) simpleGrading (1.5 1.5 1)
U without Surface Edges
U with Surface Edges
Graph
For Grading Scheme 0.8
hex (0 1 2 3 11 12 13 14) (200 10 1) simpleGrading (0.8 1.8 1)
hex (3 2 4 5 14 13 15 16) (200 10 1) simpleGrading (0.8 0.8 1)
hex (2 7 6 4 13 18 17 15) (200 10 1) simpleGrading (1.8 0.8 1)
hex (1 8 7 2 12 19 18 13) (200 10 1) simpleGrading (1.8 1.8 1)
hex (10 9 8 1 21 20 19 12) (200 10 1) simpleGrading (1.8 1.8 1)
U without Surface Edges
U with Surface Edges
Graph
CONCLUSION:
|
Mesh Grading Factor |
Velocity Magnitude(U) Approximate value |
Executing Time |
|
0.2 |
1.1m/s |
153.89s |
|
0.5 |
1.1m/s |
156.82s |
|
0.8 |
1.1m/s |
155.07s |
|
1 |
1.1m/s |
160.07s |
- By changing the simple grading factor from the value of 0.8 to 0.2 the mesh becomes finer and the solution becomes very accurate.
- From the graph, it can be seen that the value of velocity in all the cases ti be approximate as 1.1m/s at a distance of 0.085 from the inlet in X-axis.
- The Execution time is lower for lower meshing grading factor