[lammps-users] bounce-back boundary

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1

Dear,

–>> velocity, V_upper
------------------------------------ wall

particles

------------------------------------wall
<<–velocity V_lower

When I do NEMD simulation, there are two walls in xy plane which is periodic boundary, and I need a bouce-back boundary near walls.
How can I do? any suggestions?

Thanks in advance.

2

LAMMPS has a fix wall/reflect command, but
I don't think of it typically being used with NEMD
models. See the NEMD howto sub-section in
doc/Section_howto.html for details.

Steve

3

Sir，

Thanks for your suggestion, I have read the howto sub-section. But I think the fix deform command is not suitable for my simulation.

I only need create a velocity profile and not change simulation box . I want to use bounceback reflection to reproduce a no-slip boundary condition , whereby if
(V_particle_old *n_wall) < 0
for a particle in the wall region, then its velocity is reassigned as
V_particle_new = 2 * V_wall - V_particle_old

There maybe other methods to deal with it, BUT I have no ideas with lammps. It’s appreciated if some kind people give some advice. Thanks a million.

-------->> V_upper_wall
------------------------------------>

particles

<-----------------------------------
<<------- V_lower_wall

2008/4/14, Steve Plimpton <sjplimp@…24…>:

4

You'd have to write your own fix to implement this
BC.

Steve