Fix wall/gran command

Dear LAMMPS users,

I want to simulate spherical particle packing in a big hollow sphere region. For fix wall/region command, only the center of the sphere is confined to the sphere region. For fix wall/gran command, the entire spheres are confined inside the sphere region, but this command only allows plane and cylinder boundary.

Do you know how to set the wall boundary of a sphere region?

Thank you in advance!

Best wishes,

Did you notice that there is also a fix wall/gran/region command?