Implicit time integration

Submitted by AliBlues on Wed, 07/25/2018 - 15:10

Hello,
Is there a way to select implicit Euler or Crank-Nicolson for a particular force exerted on the particle. It seems there is a possibility to integrate ONLY the drag force implicitly:
https://github.com/CFDEMproject/LIGGGHTS-PUBLIC/blob/master/src/fix_cfd_...

If this is true, then it seems this should be even simpler for an external force exerted on the particle (e.g. electromagnetic). It is important to use implicit integration when considering a coupled CFD-DEM which also includes such external forces on particles for stability reasons, other wise it just becomes too impractical to carryout these simulations.
I would very much appreciate your input on how to proceed and the steps to follow (it was quite difficult to see the steps from the fix_cfd_coupling_force_implicit)

Thanks
Ali

paul | Fri, 07/27/2018 - 09:18

Have you tried setting implDEMForce false in constant/couplingProperties -> props of your drag model?

If you enable verbosity, you will see that only an explicit drag force and no drag force coefficient / fluid velocity is communicated to LIGGGHTS.