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[Robert Caulk <question699272@xxxxxxxxxxxxxxxxxxxxx>]

Question #699272 on Yade changed:
https://answers.launchpad.net/yade/+question/699272

Robert Caulk proposed the following answer:
Hello,

>>Can I directly use these two values or I should do a calibration to
choose the optimum values knowing that my filter is fixed and only the
fine particles are moving.

It is just a trade off of accuraacy, and in some cases stability. If you
have alot of deformation, you should be remeshing more frequently. If
the problem is quasistatic, then you dont need to do it very often. Just
remember that force vectors will not update until the mesh is updated.
So you if you have particles moving alot based on certain
pressure/viscous forces, then the orientation of those forces will be
outdated quickly if you arent remeshing enough. defTolerance is trying
to detect when the deformation warrants a new remesh, but it is a
relatively expensive operation too.

>>My question is: Is multicore CPU has the same meaning as parallel
computation? if yes this means I should put the value equal to 4 right?

Yes.

>>Finally is there any criteria to define the timestep?

See our paper [1] where we discuss this. It is really dependent on your
regime: stiffness, viscous, or some combination of the two. It is a
difficult problem to solve - there will always be some trial and error
involved unless you solve for the eigenvalues of the conductivity
matrix. Which is quite expensive on its own.

>> I used to increase the density of the fine particles as a tool to
increase the time step when I used to do dry filtration tests under
gravity. Do you think it is okay to do the same thing here?

Yes you can do that assuming inertial effects are negligible in the
system.

Cheers,

Robert

[1]https://linkinghub.elsevier.com/retrieve/pii/S0010465519303340

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