[Tianyz]

Originally Posted by mAlletto

Hello,


yes better avoid regions of strong gradients where to place the overset boundary.




Best


Michael

Thank you for your reply!

[mAlletto]

Cubic should be 4th order accurate. So the dissipation is least. Which leads to the strongest vortexes and hence highest lift. Unfortunately I do not have an explanation why the frequency changes.

Best

Michael

[Tianyz]

Originally Posted by mAlletto

Cubic should be 4th order accurate. So the dissipation is least. Which leads to the strongest vortexes and hence highest lift. Unfortunately I do not have an explanation why the frequency changes.

Best

Michael

Thank you for your reply, Michael, I appreciate it.

Best,
Tianyang

[mibo27]

Hello,
Can you please explain what's the purpose of each transformPoints command in Allrun.pre

runApplication transformPoints -translate '(-10 0.0 0.0)'
mv log.transformPoints log.transformPointsTranslate

runApplication transformPoints -rotate '((0 1 0)(0 0 1))'
mv log.transformPoints log.transformPointsrotate
runApplication transformPoints -scale '(0.0016 1.2 0.0016)'
mv log.transformPoints log.transformPointsscale
runApplication transformPoints -translate '(0 0.06 0.0)'


Thank you

[ansab_sindhu]

Hi,
Just want to know why the gravity was activated in the y direction while the motion is simulated in the x and Z directions.
Also, how can we understand the effect of added mass? As you have not included added mass in the frequency calculation.

[mAlletto]

Which test cases are you refering to. If the motion is in X and Z and Gravity in y It means it has no effect on the motion. Added mass is the work required to displace the fluid surrounding the cylinder

[dthakur]

Originally Posted by ansab_sindhu

I am learning Vortex Induced Vibrations and want to seek guidance from you.

I run the tutorial for Morphing mesh case to validate the results of Mittal (2 DoF). I calculated the values for the case of U*=4 , m*=10,Re=100
The values for the simulation parameters come out to be:

nu= 1.0496E-06
K=148.28
RhoInf=148171.24

The results of the X and Z centre of mass comes to be way lower than the published in your paper. Please guide me. In the below text, I have mentioned my dynamicMeshDict file.

sixDoFRigidBodyMotionCoeffs
{

accelerationRelaxation 1.0; // 1
accelerationDamping 1.0; //1.0

patches (cylinder);
innerDistance 0.0008; //1.0 // equal to cylinder Radius
outerDistance 0.032; // 0.032 // near the main domain boundary

mass 0.03575;
centreOfMass (0.0 0.0 0.0); // initially the cylinder is at the origin
momentOfInertia (4.3472E-07 1.144E-08 4.3472E-07);

g (0 -9.81 0);
rho rhoInf;
rhoInf 14817.12; //1.0e-15 // this value should be as per the nu and rho value in transport properties
report on;

solver
{
type Newmark;
}

constraints
{


zxLine
{
sixDoFRigidBodyMotionConstraint line; // cylinder can displace only along the z-axis and c axis
centreOfRotation (0.0016 0.0 0.0016); // i think initially at z=d location 0.0016
direction (1 0 1);
}

yAxis
{
sixDoFRigidBodyMotionConstraint orientation; // blocked the rotation around the y-axes
centreOfRotation (0 1 0);
}
}


restraints
{
verticalHorizontalSpring
{
sixDoFRigidBodyMotionRestraint linearSpring;

anchor (0.0 0.0 0.00);
refAttachmentPt (0.0016 0.0 0.0016); // It is attached to the boundary of cylinder (radius)

stiffness 148.281; // as the case of U* 4
damping 0.00;
restLength 0;
}
}

how did you calculate the values of nu rho and k from m* Re and U*