Puff

Lagrangian puff transport model that advects a parcel of matter within a 3-D fluid velocity field defined by a DomainInfo coordinate system. The puff position in three coordinates (lev, x, y) evolves under prescribed velocity components (v_lev, v_x, v_y) scaled by coordinate transforms. Vertical boundaries (glo, ghi) are enforced via ifelse clamping of the vertical velocity with a small offset buffer: upward motion is blocked when lev > ghi−offset and downward motion when lev < glo+offset. Lateral domain boundaries trigger simulation termination (FunctionalAffect gap other:P2-C); the effective lateral boundary distance is set via grid_spacing×buffer_cells offsets from the domain edge (parameter gap other:P3-B). Migrated from EnvironmentalTransport.jl@a48559c4114eb9f06668ecf9f06235aad20f63f0 src/puff.jl:24.