To illustrate the use of direct transfer flux links, consider a simple case involving direct transfer of a species from one Cell (representing soil) to another Cell (representing plant material). This particular example file, Cell4_DirectTransfer.gsm, can be found in the Contaminant Transport Examples folder in your GoldSim directory (accessed by selecting File | Open Example... from the main menu).
Suppose that a jar contains 1 kg of soil. The soil contains 1 gram each of two species; species A is not taken up by the plant. Species B, however, is absorbed by the plant as a first order process (i.e., at a rate proportional to the amount of mass in the soil cell). The transfer rate is 10% per day.
You wish to simulate the transfer of the compound from the soil into the plant.
To simulate this system, you would do the following:
1. Create a solid called Soil and a solid called Plant_Material;
2. Define a Jar Cell containing 1 kg of Soil;
3. Define a Plant Cell containing 1 g of Plant_Material (the amount of Plant_Material is not important, as the Plant Cell is simply acting as a sink);
4. Create a direct transfer flux link between the Jar Cell and the Plant Cell.
5. Specify the simulation settings (i.e., duration and timesteps), and run the model.
The output of this simulation, in the form of time histories of the masses of the two species in both Cells, is shown below:
Note that the mass of species A does not change in either Cell, while the mass of species B decreases exponentially in the Jar Cell (and increases accordingly in the Plant Cell).