BlockMesh Drill Down Challenge
The main aim of this project is to simulate the flow through the backward facing step by using the blocks in icoFoam solver and postprocess the results like velocity profile at the step of 0.085m from the start point of the blocks.
The blocks are built by one by one by using the nodes of all three axis There are 5 blocks are used for this project.The number of cells in the x-Direction is 200 and in the y-direction 10 and in the Zdirection it should be the 1.we have to edit the blockmeshdict file in order to run the simulation.
The block diagramm looks like this in 2D and Isometric view
The below shown code for the simple grading .we are edit this code in the blockMeshdict file located in system folder.
/*--------------------------------*- 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)//point 0
(8 0 0)//point 1
(8 0.5 0)//point 2
(0 0.5 0)//point 3
(8 1 0)//point 4
(0 1 0)//point 5
(20 1 0)//point 6
(20 0.5 0)//point 7
(20 0 0)//point 8
(20 -1 0)//point 9
(8 -1 0)//point 10
(0 0 0.1)//point 11
(8 0 0.1)//point 12
(8 0.5 0.1)//point 13
(0 0.5 0.1)//point 14
(8 1 0.1)//point 15
(0 1 0.1)//point 16
(20 1 0.1)//point 17
(20 0.5 0.1)//point 18
(20 0 0.1)//point 19
(20 -1 0.1)//point 20
(8 -1 0.1)//point 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
(
);
// ************************************************************************* //For pressure boundary conditions:
/*--------------------------------*- 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;
}
Noslipwalls
{
type zeroGradient;
}
frontAndBack
{
type empty;
}
}For velocity Boundary conditions
/*--------------------------------*- 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;
}
Noslipwalls
{
type noSlip;
}
frontAndBack
{
type empty;
}
}
Controldict conditions
/*--------------------------------*- 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 0.5;
deltaT 0.00001;
writeControl timeStep;
writeInterval 20;
purgeWrite 0;
writeFormat ascii;
writePrecision 6;
writeCompression off;
timeFormat general;
timePrecision 6;
runTimeModifiable true;
// ************************************************************************* //The pressure ,velocity boundary conditions in folder 0 will remain same for all the mesh grading factor we just change the block and controldict file in the system remains also same for every mesh grading factor.If the courant number is exceeds the maximum limit then we have to change the dt value for every mesh grading factor. The starting time is zero and the end time is 0.5
For simple Meshing grade scheme of 1:
The mesh block diagram
The pressure variations diagram
The velocity variations diagram
The velocity Profile:
The velocity profile at a distance of 0.085 m near the step from the inlet as shown below
For simple Meshing grade scheme of 0.2:
For this we kept the code same and a little bit changes are done i.e in blocks .what we changes is shownbelow remaning code has no changes.
blocks
(
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)
);The mesh block diagram
The pressure variations diagram
The velocity variations diagram
The velocity Profile
The velocity profile at a distance of 0.085 m near the step from the inlet as shown below
For simple Meshing grade scheme 0.5:
For this we kept the code same and a little bit changes are done i.e in blocks .what we changes is shownbelow remaning code has no changes.
blocks
(
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)
);
The mesh block diagram
The pressure variations diagram
The velocity variations diagram
The velocity Profile
The velocity profile at a distance of 0.085 m near the step from the inlet as shown below
For simple Meshing grade scheme 0.8:
For this we kept the code same and a little bit changes are done i.e in blocks .what we changes is shownbelow remaning code has no changes.
blocks
(
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)
);The mesh block diagram
The pressure variations diagram
The velocity variations diagram
The velocity Profile
The velocity profile at a distance of 0.085 m near the step from the inlet as shown below
Conlusion:
All The velocity graphs obtainted from the different meshing grading factors are similiar with a negligible variations.As the mesher size is lower i.e for finer mesh we can visualize the accurate output.