Advection and Diffusion of Particulates to/from Pipes

Suspended solids can advect and diffuse into Pipes, and can advect out of Pipes (mass cannot diffuse out of Pipes).

Suspended solids can advect into a Pipe from another pathway containing suspended solids. Suspended solids can also diffuse into a Pipe from a Cell or Aquifer containing suspended solids. The species mass associated with the suspended solids in the upstream (Outflow or Outflux) pathway enter the Pipe regardless of whether suspended solids are specified as being present in the Pipe. When suspended solids (carrying species mass) enter a Pipe from another pathway, conceptually, the particulates are assumed to immediately disintegrate upon entering the Pipe (releasing their species mass to the fluid in the Pipe). If suspended solids are present in the Pipe, the species mass will then partition onto these solids.