&translate z_trigger = 0.05, z_lower = 0.02, z_upper = 0.055 &endThis specifies that when the first particle passes cm, the mesh will be contracted to cover the region from cm to cm. Thereafter, each time a particle advances by one longitudinal mesh spacing, the grid will be translated that same distance in the +z direction.
The boundary conditions are changed to Neumann on the upper, right, and left boundaries and Dirichlet on the lower boundary.
&translate z_lower = <zMin>, z_upper = <zMax>, z_trigger = <z0>, &endwhere
<zMax>are the minimum and maximum longitudinal coordinates for the original problem mesh, and
<zMax>-, where is the mesh spacing.