Advection and Diffusion of Particulates to/from Aquifers

Suspended solids can advect and diffuse into and out of Aquifers.

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

Particulates can diffuse out of an Aquifer to a downstream pathway if (and only if) the Enable dispersive and diffusive outfluxes to downstream pathway(s) box is checked. In this case, the suspended Solid concentration in the Influx pathway is assumed to be zero when computing the diffusive gradient (and, hence, the diffusive flux becomes uni-directional).

When mass associated with particulates leave an Aquifer, the Solid does not have to be specified as being present in the Influx pathway. Conceptually, the particulates are assumed to immediately disintegrate upon entering the Influx pathway, with the species mass which was associated with them instantaneously partitioning among the available media in the pathway.