Colloids and Particulates

In some cases, when attempting to simulate particulate or colloidal matter in GoldSim, it may be appropriate to simply treat them as another species The chemical (or non-chemical, such as bacterial or viral) constituents that are stored and transported through an environmental system in a contaminant transport model. In GoldSim, the Species element defines all of the contaminant species being simulated (and their properties)..

In many cases, however, the colloids or particulates are actually more properly thought of as another medium. GoldSim has special features that allow you to represent particulates in Cells, Aquifers and Pipes.

In both cases, you define the particulate as a Solid medium (and hence the particulate can act as a storage and transport medium for species). You then directly specify a particulate mass (or for Pipes and Aquifers, a concentration) in each pathway.

Occasionally, you may want the particulates to act as a transport medium, but you may also wish to carry out a mass balance on the particulate concentration (i.e., you can't simply assume that it is constant). In order to do this, you could specify the particulate as a species and a medium. You would then define the concentration of the medium in a pathway by referencing the species concentration in the pathway. This would create a recursive system, and would necessarily involve the use of previous value elements (i.e., the medium concentration would be specified as the species concentration at the previous timestep A discrete interval of time used in dynamic simulations.).