Week 8 - Simulation of a backward facing step in OpenFOAM
open terminal
open foam tutarioal using shortcut tut
open cavity file using below command
cd incompressible/icoFoam/cavity/
copy cavity file to run file with name of test_cavity using this command
cp -r cavity $FOAM_RUN/test_cavity
- To create block/backward facing step geometry
first the copied file is saved in run
file to open that file the run file is opened using run shortcut
cd test_cavity/system/
gedit blockMeshDict
for grading factor 1
`gf=(size of end cell)/(size of initial cell)`
/--------------------------------- C++ -----------------------------------\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 10
\\/ M anipulation |
\---------------------------------------------------------------------------/
FoamFile
{
format ascii;
class dictionary;
object blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
convertToMeters 1;
vertices
(
(0 0 0)//0
(0.08 0 0)//1
(0.08 0.005 0)//2
(0 0.005 0)//3
(0.08 0.01 0)//4
(0 0.01 0)//5
(0.2 0.01 0)//6
(0.2 0.005 0)//7
(0.2 0 0)//8
(0.2 -0.01 0)//9
(0.08 -0.01 0)//10
(0 0 0.1)//11
(0.08 0 0.1)//12
(0.08 0.005 0.1)//13
(0 0.005 0.1)//14
(0.08 0.01 0.1)//15
(0 0.01 0.1)//16
(0.2 0.01 0.1)//17
(0.2 0.005 0.1)//18
(0.2 0 0.1)//19
(0.2 -0.01 0.1)//20
(0.08 -0.01 0.1)//21
);
blocks
(
hex (0 1 2 3 11 12 13 14) (80 5 1) simpleGrading (1 1 1)
hex (3 2 4 5 14 13 15 16) (80 5 1) simpleGrading (1 1 1)
hex (2 7 6 4 13 18 17 15) (120 5 1) simpleGrading (1 1 1)
hex (1 8 7 2 12 19 18 13) (120 5 1) simpleGrading (1 1 1)
hex (10 9 8 1 21 20 19 12) (120 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)
);
}
fixedWalls
{
type wall;
faces
(
(4 5 16 15)
(4 15 17 6)
(0 1 12 11)
(9 20 21 10)
(1 10 21 12)
);
}
frontAndBack
{
type empty;
faces
(
(3 2 1 0)
(2 3 4 5)
(2 4 6 7)
(1 2 7 8)
(10 1 8 9)
(11 12 13 14)
(13 15 16 14)
(13 18 17 15)
(21 20 19 12)
);
}
);
mergePatchPairs
(
);
// ************************* //for grading factor 0.2
/--------------------------------- C++ -----------------------------------\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 10
\\/ M anipulation |
\---------------------------------------------------------------------------/
FoamFile
{
format ascii;
class dictionary;
object blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
convertToMeters 1;
vertices
(
(0 0 0)//0
(0.08 0 0)//1
(0.08 0.005 0)//2
(0 0.005 0)//3
(0.08 0.01 0)//4
(0 0.01 0)//5
(0.2 0.01 0)//6
(0.2 0.005 0)//7
(0.2 0 0)//8
(0.2 -0.01 0)//9
(0.08 -0.01 0)//10
(0 0 0.1)//11
(0.08 0 0.1)//12
(0.08 0.005 0.1)//13
(0 0.005 0.1)//14
(0.08 0.01 0.1)//15
(0 0.01 0.1)//16
(0.2 0.01 0.1)//17
(0.2 0.005 0.1)//18
(0.2 0 0.1)//19
(0.2 -0.01 0.1)//20
(0.08 -0.01 0.1)//21
);
blocks
(
hex (0 1 2 3 11 12 13 14) (80 5 1) simpleGrading (0.2 5 1)
hex (3 2 4 5 14 13 15 16) (80 5 1) simpleGrading (0.2 0.2 1)
hex (2 7 6 4 13 18 17 15) (120 5 1) simpleGrading (5 0.2 1)
hex (1 8 7 2 12 19 18 13) (120 5 1) simpleGrading (5 5 1)
hex (10 9 8 1 21 20 19 12) (120 10 1) simpleGrading (5 5 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)
);
}
fixedWalls
{
type wall;
faces
(
(4 5 16 15)
(4 15 17 6)
(0 1 12 11)
(9 20 21 10)
(1 10 21 12)
);
}
frontAndBack
{
type empty;
faces
(
(3 2 1 0)
(2 3 4 5)
(2 4 6 7)
(1 2 7 8)
(10 1 8 9)
(11 12 13 14)
(13 15 16 14)
(13 18 17 15)
(21 20 19 12)
);
}
);
mergePatchPairs
(
);
// ************************* //- for controlDist
gedit controlDist
/--------------------------------- C++ -----------------------------------\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 10
\\/ M anipulation |
\---------------------------------------------------------------------------/
FoamFile
{
format ascii;
class dictionary;
location "system";
object controlDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
application icoFoam;
startFrom startTime;
startTime 0;
stopAt endTime;
endTime 0.5;
deltaT 0.0002;
writeControl runTime;
writeInterval 0.1;
purgeWrite 0;
writeFormat ascii;
writePrecision 6;
writeCompression off;
timeFormat general;
timePrecision 6;
runTimeModifiable true;
// ************************* //- Velocity field
cd ../0
gedit U
/--------------------------------- C++ -----------------------------------\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 10
\\/ M anipulation |
\---------------------------------------------------------------------------/
FoamFile
{
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 (10 0 0);
}
outlet
{
type zeroGradient;
}
fixedWalls
{
type noSlip;
}
frontAndBack
{
type empty;
}
}
// ************************* //- Pressure field
gedit p
/--------------------------------- C++ -----------------------------------\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 10
\\/ M anipulation |
\---------------------------------------------------------------------------/
FoamFile
{
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;
}
}
// ************************* //- physical property
cd ../constant
gedit physicalProperties
/--------------------------------- C++ -----------------------------------\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 10
\\/ M anipulation |
\---------------------------------------------------------------------------/
FoamFile
{
format ascii;
class dictionary;
location "constant";
object physicalProperties;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
nu [0 2 -1 0 0 0 0] 0.01;
// ************************* //once the all the above parameter defined
blockMesh :- is used to mesh the block
checkMesh :- is used to check the mesh of the block
icoFoam :- this is solver used to solve the problem
paraFoam :- script that launches ParaView, by default using the reader module supplied with OpenFOAM
once the paraFoam is opened the field is selected
run program look velocity and presre behaviour on block
the velocity profile graph is ploted using plot over command at x 0.085
Results
Conclusion
from above two plot of velocity grading its seen that velocity profile look more smooth in without grading block then the with rading factor