"Frozen" dynamic meshing

maasyraf3 · April 23, 2017, 07:57

GREETINGS to all Foamers, 
 
My name is Amy which currently are doing my master research project by dealing with oscillating cylinders. I have went through each replies in this thread and its related link provided, but still I think I dont have the answer. 
 
I really need your series of advices, in regards with my oscillating circular cylinder in dynamic meshing. I use pimpleDyMFoam, OF 4.0 to solve my case 
 
I have provide all the necessary parameters that similar with my experimental works ( actual setup) but after almost 2 weeks, still the simulation in openFoam not favourable to my experiment result. (I attached the video for actual experiment in my university lab) 
 
The GIF file : https://www.cfd-online.com/Forums/at...1&d=1492856466 
 
Has uploaded in youtube link: https://youtu.be/V627hD_ktVA 
 
 
I did modify and tried various Reynold Number value in order to see the effect to the flow, but still the same result. It seems that the flow "not so smooth" as per actual. 
 
My setup which is mass-spring-damping system are as follows: 
 
1) Diameter of the cylinder is 50 mm ( which equal to 0.05 meter) iwith the total length is 0.65meter. My case only for 1-DOF. 
 
2) The circular cylinder should oscillate (moving) in y-direction only. As the flow passing the cylinder, the lift force from the flow should naturally force the cylinder up and down (viv phenomena) at certain amplitude. 
 
3) System stiffness is 140 N/m. And so I set two spring (70 for each spring) in the openFoam dynamicMeshDict. The sketch by hand as below:

Basically I use

Quote:

- dynamicFvMesh :dynamicMotionSolverFvMesh 
- motionSolverLibs

"libsixDoFRigidBodyMotion.so") 
- solver: sixDoFRigidBodyMotion

4) The damping of system is 0.08. The mass of the cylinder is 1.32 kg. Density of the water I use 1000 kg/m3. 
Kinematic viscosity (v) - 1e-06. And so these values I set in transportProperties file

Quote:

transportModel Newtonian; 
 
nu nu [ 0 2 -1 0 0 0 0 ] 1e-06; 
rho rho [1 -3 0 0 0 0 0] 1000;

5) Speed of the water is 0.3 m/s. 
So, here in 0 file, I set the U 0.3 m/s at inlet and internalField as well. (I dont know it is the right way or not). 
 
By using 0.3 m/s, the Reynold number is 15 000. 
I dont know, this value of Re still valid for my case file since I off the turbulenceProperties. Need helps here. 
 
6) In dynamicMeshDict, we should specify the below: 
 
- inner distance and outer distance. I'd like to ask the effect to the oscillation of the cylinder

Quote:

patches (cylinder); 
innerDistance 0.3; 
outerDistance 2;

- the rho of the rhoInf ? What the exact value I should put? the rho of the cylinder or the fluid?

Quote:

rho rhoInf; 
rhoInf 1;

7) The issue is - why after simulate is seems so "frozen" and did not work well as per actual experiment? How do I fix this.? 
 
Here I attach all the '0' , ' Constant' and 'System' of my setup. And really appreciate helps and assistance from this forum thread. I dont know, it can be my flow setup is wrong, or my dynamicMeshDict or my transportProperties. or else? 
 
I hope I can resolve this...really. Thanks in advance all !!

Best Regards - 
Amy 
amirulasyraf.utm@gmail.com 
 
********************************* 
 
 
My all case Files as below link and quote 
 
0_constant_system_cylinderVIV.zip 
 
 
0 files 
 
U :

Quote:

FoamFile 
{ 
version 2.0; 
format ascii; 
class volVectorField; 
object U; 
} 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // 
 
dimensions [0 1 -1 0 0 0 0]; 
 
internalField uniform (0.01 0 0); 
 
boundaryField 
{ 
topAndBottom 
{ 
type noSlip; 
} 
 
inlet 
{ 
type fixedValue; 
valueuniform (0.01 0 0); 
} 
 
outlet 
{ 
type zeroGradient; 
} 
 
frontAndBack 
{ 
type empty; 
} 
 
 
cylinder 
{ 
type movingWallVelocity; 
value uniform (0 0 0); 
} 
 
} 
 
// ************************************************** *********************** //

Pressure ,p

Quote:

{ 
version 2.0; 
format ascii; 
class volScalarField; 
object p; 
} 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // 
 
dimensions [0 2 -2 0 0 0 0]; 
 
internalField uniform 0; 
 
boundaryField 
{ 
 
topAndBottom 
{ 
type zeroGradient; 
} 
 
outlet 
{ 
type zeroGradient; 
} 
 
inlet 
{ 
type zeroGradient; 
} 
 
frontAndBack 
{ 
type empty; 
} 
 
cylinder 
{ 
type zeroGradient; 
} 
 
} 
 
// ************************************************** *********************** //

pointDisplacement

Quote:

FoamFile 
{ 
version 2.0; 
format ascii; 
class pointVectorField; 
location "0.01"; 
object pointDisplacement; 
} 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // 
 
dimensions [0 1 0 0 0 0 0]; 
 
internalField uniform (0 0 0); 
 
boundaryField 
{ 
topAndBottom 
{ 
type uniformFixedValue; 
uniformValue (0 0 0); 
} 
 
inlet 
{ 
type uniformFixedValue; 
uniformValue (0 0 0); 
} 
 
outlet 
{ 
type uniformFixedValue; 
uniformValue (0 0 0); 
} 
 
cylinder 
{ 
type calculated; 
value uniform (0 0 0); 
} 
 
frontAndBack 
{ 
type empty; 
} 
}

Next, is the dynamicMeshDict file

Quote:

FoamFile 
{ 
version 2.0; 
format ascii; 
class dictionary; 
object dynamicMeshDict; 
} 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // 
 
dynamicFvMesh dynamicMotionSolverFvMesh; 
 
motionSolverLibs ("libsixDoFRigidBodyMotion.so"); 
 
solver sixDoFRigidBodyMotion; 
 
diffusivity linear inverseDistance 1 (cylinder); 
 
sixDoFRigidBodyMotionCoeffs 
{ 
patches (cylinder); 
innerDistance 0.3; 
outerDistance 2; 
 
mass 1.32; 
centreOfMass (0 0 0); 
momentOfInertia (0.1 0.1 0.1); 
orientation 
( 
1 0 0 
0 1 0 
0 0 1 
); 
angularMomentum (0 0 0); 
g (0 -9.81 0); 
rho rhoInf; 
rhoInf 1; 
report on; 
 
solver 
{ 
type symplectic; 
} 
 
constraints 
{ 
yLine 
{ 
sixDoFRigidBodyMotionConstraint line; 
centreOfRotation (0 0 0); 
direction (0 1 0); 
} 
 
zAxis 
{ 
sixDoFRigidBodyMotionConstraint axis; 
axis (0 0 1); 
} 
} 
 
restraints 
{ 
verticalSpring1 
{ 
sixDoFRigidBodyMotionRestraint linearSpring; 
 
anchor (0 0.20 0.0025); 
refAttachmentPt (0 0.05 0.0025); 
stiffness 70; 
damping 0.08; 
restLength 0.05; 
} 
 
verticalSpring2 
{ 
sixDoFRigidBodyMotionRestraint linearSpring; 
 
anchor (0 -0.20 0.0025); 
refAttachmentPt (0 -0.05 0.0025); 
stiffness 70; 
damping 0.08; 
restLength 0.05; 
} 
 
 
} 
} 
 
 
// ************************************************** *********************** //

next - transportProperties

Quote:

FoamFile 
{ 
version 2.0; 
format ascii; 
class dictionary; 
location "constant"; 
object transportProperties; 
} 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // 
 
transportModel Newtonian; 
 
nu nu [ 0 2 -1 0 0 0 0 ] 1e-06; 
rho rho [1 -3 0 0 0 0 0] 1000; 
 
 
// ************************************************** ***********************

turbulenceProperties

Quote:

FoamFile 
{ 
version 2.0; 
format ascii; 
class dictionary; 
location "constant"; 
object turbulenceProperties; 
} 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // 
 
simulationType laminar; 
 
 
// ************************************************** *********************** //

RAS properties

Quote:

FoamFile 
{ 
version 2.0; 
format ascii; 
class dictionary; 
location "constant"; 
object RASProperties; 
} 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // 
 
RASModel laminar; 
 
 
turbulence off; 
 
printCoeffs on; 
 
 
// ************************************************** *********************** //

and now - the system files 
 
the controlDict:

Quote:

FoamFile 
{ 
version 2.0; 
format ascii; 
class dictionary; 
location "system"; 
object controlDict; 
} 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // 
 
application pimpleDyMFoam; 
 
startFrom latestTime; 
 
startTime 0; 
 
stopAt endTime; 
 
endTime 60; 
 
deltaT 5e-06; 
 
writeControl adjustableRunTime; 
 
writeInterval 0.1; 
 
purgeWrite 0; 
 
writeFormat binary; 
 
writePrecision 6; 
 
writeCompression off; 
 
timeFormat general; 
 
timePrecision 6; 
 
runTimeModifiable true; 
 
adjustTimeStep yes; 
 
maxCo 0.5; 
 
functions 
{ 
#include "cuttingPlane" 
} 
 
// ************************************************** *********************** //

the decomposeParDict:

Quote:

FoamFile 
{ 
version 2.0; 
format ascii; 
class dictionary; 
object decomposeParDict; 
} 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // 
 
numberOfSubdomains 6; 
 
method scotch; 
// method ptscotch; 
 
simpleCoeffs 
{ 
n (4 1 1); 
delta 0.001; 
} 
 
hierarchicalCoeffs 
{ 
n (3 2 1); 
delta 0.001; 
order xyz; 
} 
 
manualCoeffs 
{ 
dataFile "cellDecomposition"; 
} 
 
 
// ************************************************** *********************** //

the fvschemes:

Quote:

FoamFile 
{ 
version 2.0; 
format ascii; 
class dictionary; 
location "system"; 
object fvSchemes; 
} 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // 
 
ddtSchemes 
{ 
default Euler; 
} 
 
gradSchemes 
{ 
default Gauss linear; 
} 
 
divSchemes 
{ 
default none; 
div(phi,U) Gauss linear; 
div((nuEff*dev(T(grad(U))))) Gauss linear; 
div((nuEff*dev2(T(grad(U))))) Gauss linear; 
} 
 
laplacianSchemes 
{ 
default Gauss linear corrected; 
laplacian(diffusivity,cellMotionU) Gauss linear uncorrected; 
} 
 
interpolationSchemes 
{ 
default linear; 
} 
 
snGradSchemes 
{ 
default corrected; 
} 
 
fluxRequired 
{ 
default no; 
pcorr ; 
p ; 
} 
 
 
// ************************************************** *********************** //

the fvsolution:

Quote:

FoamFile 
{ 
version 2.0; 
format ascii; 
class dictionary; 
location "system"; 
object fvSolution; 
} 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // 
 
solvers 
{ 
pcorr 
{ 
solver GAMG; 
tolerance 0.02; 
relTol 0; 
smoother GaussSeidel; 
nPreSweeps 0; 
nPostSweeps 2; 
cacheAgglomeration no; 
nCellsInCoarsestLevel 10; 
agglomerator faceAreaPair; 
mergeLevels 1; 
} 
 
p 
{ 
solver GAMG; 
tolerance 0; 
relTol 0.01; 
smoother GaussSeidel; 
nPreSweeps 0; 
nPostSweeps 2; 
cacheAgglomeration no; 
nCellsInCoarsestLevel 10; 
agglomerator faceAreaPair; 
mergeLevels 1; 
} 
 
pFinal 
{ 
$p; 
tolerance 1e-06; 
relTol 0; 
} 
 
U 
{ 
solver smoothSolver; 
smoother symGaussSeidel; 
tolerance 1e-05; 
relTol 0.1; 
} 
 
UFinal 
{ 
$U; 
tolerance 1e-05; 
relTol 0; 
} 
 
cellMotionUx 
{ 
solver PCG; 
preconditioner DIC; 
tolerance 1e-08; 
relTol 0; 
} 
cellMotionUxFinal 
{ 
solver PCG; 
preconditioner DIC; 
tolerance 1e-08; 
relTol 0; 
} 
 
"cellDisplacement.*" 
{ 
solver GAMG; 
tolerance 1e-5; 
relTol 0; 
smoother GaussSeidel; 
cacheAgglomeration true; 
nCellsInCoarsestLevel 10; 
agglomerator faceAreaPair; 
mergeLevels 1; 
} 
 
} 
 
PIMPLE 
{ 
correctPhi yes; 
nOuterCorrectors 2; 
nCorrectors 1; 
nNonOrthogonalCorrectors 0; 
pRefCell 1001; 
pRefValue 0; 
} 
 
relaxationFactors 
{ 
fields 
{ 
} 
equations 
{ 
"U.*" 1; 
} 
} 
 
// ************************************************** *********************** //

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