I added the possibility that the restitution coefficient varies with a local Stokes number of the particle (motion of particles in a viscous fluid) to pair_gran_hooke_history and fix_wall_gran_hooke_history.
The code and an example script is provided.
One has to enable a "viscousflag" (similar to dampflag for instance) into pair style or fix wall definition. The viscous flag is :
pair_style gran/hooke/history rolling_friction cdt viscous st
It will work only for hookean (history?) contacts. One has to provide the 3 parameters needed for the viscous damping :
fix m7 all property/global FluidViscosity peratomtypepair 1 0.001
fix m8 all property/global MaximumRestitution peratomtypepair 1 0.9
fix m9 all property/global CriticalStokes peratomtypepair 1 35.0
See ref for more explanation: Legendre, D., Daniel, C., Guiraud, P., 2005. Experimental study of a drop bouncing on a wall in a liquid. Physics of Fluids 17 (1), 1e13.
Cheers !
Joris
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ckloss | Wed, 12/05/2012 - 18:51
Hi Joris,
Hi Joris,
that sounds very interesting! I'd be happy to take a look. Can you maybe refer to the reference that you were following?
thanks, Christoph
jorisheyman | Sat, 12/08/2012 - 10:47
They are a lot of paper
They are a lot of paper discussing the dependance on the stokes number, for instance :
Gondret, P., E. Hallouin, M. Lance, and L. Petit, Experiments on the motion of a solid sphere toward a wall: from viscous dissipation to elastohydrodynamic bouncing, Physics of Fluids, 11, 2803-2805, 1999.
Gondret, P., M. Lance, and L. Petit, Bouncing motion of spherical particles in fluids, Physics of Fluids, 14, 643-652, 2002.
Zenit, R., and M.L. Hunt, Mechanics of immersed particle collisions, Journal of Fluids Engineering, 121, 179-184, 1999.
Schmeeckle, M.W., J.M. Nelson, J. Pitlick, and J. Bennett, Interparticle collision of natural sediment grains in water, Water Resources Research, 37, 2377-2391, 2001.
The parametrisation I used is from legendre et al (2005) : Legendre, D., Daniel, C., Guiraud, P., 2005. Experimental study of a drop bouncing on a wall in a liquid. Physics of Fluids 17 (1), 1e13.
Its a basic exponential. At the end there is 3 free parameter: viscosity of the fluid, maximum restitution coefficient (for high stokes) and critical stokes number (where the transition from damped to rebound occurs).
Seems to work quite well in my case. I'll try to join the lib files in a other post.
ckloss | Tue, 12/25/2012 - 15:08
Hi Joris,
Hi Joris,
thanks! I'll have a look and eventually include you contribution into the next release!
Cheers and happy holidasys,
Christoph
ckloss | Sun, 01/06/2013 - 23:10
Hi Joris,
Hi Joris,
thanks for your contribution, I'll include it into the next release!
Cheers,
Christoph
hrvig | Wed, 04/27/2016 - 14:01
Only for hookian style?
Do you also plan to include it in the gran model hertz style?
So far it seems to be only implemented for the hookian style