hybrid granular colloid

Dear LAMMPS users,

I’m working with a LAMMPS fork which is called LIGGGHTS and is based on lammps-10Mar10. It has the full power of LAMMPS with some additions.

My object is to set up a simulation for a dense suspension (volfrac: 0.6). To reduce the complexity of the model I’m trying to include the fluid phase with “pair_style lubricate”. I compiled (without any errors) the colloid-package which is necessary for pair_style lubricate. In the input-script I put “atom_style hybrid colloid granular” and “pair_style hybrid /overlay gran/hooke/history 1 0 lubricate 100 1 1 1 0 {cutinner} {cutoff} 0 18283” to set up the hybrid simulation.

When I start the solver I get the error message “ERROR: Pair lubricate cannot be used with atom attributes diameter or rmass”.

For granular I have to define the density and the diameter and for colloid I have to set mass and shape. When I define both I get the error message printed above and when I omit mass or shape I get other error messages.

What I have to change to set up this hybrid simulation? In the mailing list I found a mail from Thomas Wagner, Wed, 2 Sep 2009 with an answer from Steve. But he worked with an older LAMMPS version. Is it still impossible to set up a hybrid simulation the way I tried it with my newer LAMMPS version?

Thanks for help


I can't remember the details for the March 2010 version,
but pair lubricate in the current version of LAMMPS is
meant to be used as part of fast-lubrictation dynamics
models (a simplified form of Stokesian dynamics).
So I don't know if it makes sense for what you are trying
to do.

In the current version there is a pair lubricate for monodisperse
systems and a pair lubricate/poly for polydisperse. Only
the latter allows for particles with varying radii.