ESyS-Particle

CheckPoint for rotational spheres

Asked by Gonzalo Tancredi

Hi all

In the case of using RotSpheres, is it possible to store the rotational status of the particles with the CheckPointer?
If I use:
sim.createCheckPointer ( CheckPointPrms ("cpt/cpt", 0, nt, n_snap))

I get the same ouput formar as with NRotSpheres
(the 22 field format with position, velocities, forces, ...)

Regards

Gonzalo

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Dion Weatherley (d-weatherley) said : 		#1

Hi Gonzalo,

Yes, when setting ParticleType="RotSphere" in ESyS-Particle simulations, the checkpointer should output additional fields for angular velocity and particle orientation (via 4 quaternion parameters, Q0,Q1,Q2,Q3). More information about the checkpointer output formats is available here:
https://answers.launchpad.net/esys-particle/+faq/708

I am unsure why your current checkpointer is not saving this information. If you have selected to use "RotSpheres" then the checkpointer should work correctly.

Could you please post (or email me) your simulation script(s)?

Cheers,

Dion

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Gonzalo Tancredi (gonzalo) said : 		#2

Hi Dion

I'm sorry but I found the error.
I forgot to put sim.initNeighbourSearch(particleType="RotSphere", ....

Nevertheless, the output has some differences.
I have 29 fields per particle in the CheckPointer files, but in the information of the above link, there should be 30.
(the same 22 as NRot + 8 more: 1 for Moment of Inertia, 4 for orientation Quarternion Q0,Q1,Q2,Q3, 3 for Angular Velocity X,Y,Z).

Is the information correct or do I missing something?

I'm sending the script by email because it is pretty long.

Cheers

Gonzalo

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Gonzalo Tancredi (gonzalo) said : 		#3

Hi Dion

I found out the problem.
While the saveCheckPointData saves the 30 fields including:
1 for Moment of Inertia, 4 for orientation Quarternion (Q0,Q1,Q2,Q3), 3 for Angular Velocity (X,Y,Z)

the saveSnapShotData saves 29 fields including:
 4 for orientation Quarternion (Q0,Q1,Q2,Q3), 3 for Angular Velocity (X,Y,Z)
(the Moment of Inertia is not saved).

Cheers

Gonzalo

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Dion Weatherley (d-weatherley) said : 		#4

Hi Gonzalo,

Thanks for identifying this issue. It would appear there is a bug in the SnapShooter for saving RotSphere information. We will look into this further.

For now, I recommend that users employ the CheckPointer for saving output data rather than the SnapShooter, when conducting RotSphere simulations.

Cheers,

Dion