Cell Pathway Example 2: Advection and Equilibrium Partitioning

Cell Pathway elements can simulate the movement of mass into and out of the cell by transport with a moving fluid (i.e. advection). They can be used simulate partitioning between the liquid and solid media. In this example, the pond system has a fluid outflow which causes mass to leave the Cell Pathway, "Pond", via advective transport. Equilibrium partitioning is also represented for species A.

• The mass flux rate (M/T) from "Pond" to "Sink" is the specified discharge rate (V/T) multipled by the mass concentration (M/V) in the Cell Pathway.
• The process of equilibrium partitioning acts to always keep the mass of species A partitioned between the media according to the specified equilibrium partitioning rate (e.g. specified in m3/kg).

10 g of species A and B are initially in the Pond System. The Sink is used to provide an outflow from the "Pond" element. In this case, this is a specified rate outflow. Make sure the name starts with "Sink" so that you don't trigger warnings in the Run Log.

GoldSim calculates mass transport so it determines the Species mass in the Cell Pathway. Concentration is then derived as the Species mass / volume for fluid and Species mass / mass for solids. For species A the partitioning ratio between water and sediment is constant. Species B does not have partitioning.

Total mass in the Pond system decreases over time proportional to the outflow discharge times species concentration in water. Species A is partitioned so that less mass is available in water to leave the "Pond" at early times relative to species B.

To Open the Model File:

1. Start GoldSim
2. Click on the File and select Open Example...
3. Browse to General Examples --> Contaminant Transport Examples
4. Select the file called Cell2_AdvectionNoDecay.gsm