[lammps-users] Hooper

Dear LAMMPS users,
Can we make hooper for granular flow in lammps? And, is it possile to genrate sound waves in lammps?

People have done it by hacking in walls with different geometric shapes.
A la the fix wall/gran command. You can always generate a rough wall (made
of particles) and freeze them in whatever shape you want. For sound
waves you can use the fix move command to move boundary atoms in a
way that generates a wave at a boundary.