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Alletto - 2022 - Comparison of overset mesh with morphing mesh

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Old   May 13, 2023, 14:42
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Quote:
Originally Posted by mAlletto View Post
Hello,


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




Best


Michael
Thank you for your reply!
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Old   May 13, 2023, 16:02
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Michael Alletto
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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.

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Old   May 15, 2023, 09:56
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Quote:
Originally Posted by mAlletto View Post
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
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Old   December 15, 2023, 19:46
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Amine Gorine
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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
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Old   August 13, 2024, 16:20
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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.
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Old   August 15, 2024, 10:50
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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
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Old   October 24, 2024, 16:40
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Quote:
Originally Posted by ansab_sindhu View Post
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*
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