Aquifer Example: Advection, Dispersion and Retardation in an Aquifer

The Aquifer element in GoldSim is a complex element. Under the hood, GoldSim creates an Aquifer element at runtime by creating a cell net from the specified number of Cell Pathway elements ("Number of Cells:") in the "Definition" tab of the Property dialog. The Aquifer element will calculate or simulate mass transport in a saturated or "fixed volume" system. The primary mass transport related processes that are available for representation in the Aquifer include:

• Advection (needs to be approximately constant)
• Dispersion (you will always get dispersion whether you specify it or not)
• Retardation (i.e. sorption under equilibrium partitioning). Partitioning coefficients are specified in the solid media properties so adding a medium with defined partitioning coefficients tells the Aquifer element to simulate retardation.

There are additional things that you can do with the Aquifer but these are "Advanced Topics" and you should read the manual.

1 mg/day of each species is injected into the column. This provides a constant rate input boundary condition on the "Aquifer" named "Column". The Sink is used to provide an outflow from the "Aquifer" 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.

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 Aquifer.gsm