[lammps-users] Problem in command fix wall/gran + wiggle (cylinder geometry)

Hi all

In my simulation I want to oscillate a wall. I was using a retangular box and oscillating the zplane by the command fix wall/gran + keyword wiggle:
fix id all wall/gran zplane 0.0 2000.0 40.0 0.50 wiggle z 2.0 3.0

Now, I'm using a cylinder container and the command fix wall/gran (fix id all wall/gran zcylinder 6.125 40.0 0.5 wiggle z 2.0 3.0), but it don't function correctly. The wall z don't oscillate. I only modified the geometry (rectangular for cylinder).

Why it happens?

Ah! I'm using the version lammps-17Jul06.

Best regards.


Why don't you post your input script for the smallest possible
problem you think doesn't work correctly.


I looked at your input scripts. The zcylinder wall is wiggling just fine.
What you may not realize is that when you wiggle a zplane wall
in the z direction, you are moving the top/bottom surfaces of the
system. But a zcylinder wall is the side walls of the system. When
you wiggle it in the z direction, it has only a small effect on the
particles due to tangential friction. But you can see that it
is working by comparing the thermo output when it is on/off. The
answers will be different.

What I think you want to do for your zcylinder case, is also
define a zplane for the bottom. And also wiggle it up/down.
This will effectively wiggling the entire cylindrical container (bottom and

Also you don't need the fix wall/reflect boundaries, since your wall/gran
will enclose the entire set of particles.