In order to represent the wide variety of transport pathways which you may wish to simulate, GoldSim provides five different pathway element types, which can be used interchangeably in a model:
- Cell pathways act as mixing cells.
Within a Cell, all 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). mass is assumed to be instantaneously and completely mixed and equilibrated among all of the Cell's media Materials (such as water, sand, clay, air) that constitute (are contained within) transport pathways. GoldSim provides two types of elements for defining media: Fluids and Solids.. Solubility constraints can be imposed within Cell pathways. When multiple Cells are linked together, the behavior of the Cell network is mathematically identical to a network of finite difference nodes describing a coupled system of differential equations. - Aquifer pathways are used to represent
features that essentially behave as fluid conduits or stream tubes.
An Aquifer pathway actually performs its computations by creating a temporary set of linked Cell elements during the simulation, which are subsequently removed at the end of the simulation. They can be applied to a broad range of advectively-dominated mass transport systems involving one-dimensional advection, longitudinal dispersion, diffusion, retardation, decay and ingrowth. - Pipe pathways are also used to represent
features that essentially behave as fluid conduits or stream tubes.
Pipe pathways use a Laplace transform A method for solving certain types of differential equations that involves transforming the equations into an algebraic form that can be readily solved, and then using an inverse transform to retrieve the solutions of the original problem. approach to provide analytical solutions to a broad range of advectively-dominated mass transport systems. Because they can represent processes such as matrix diffusion, they are particularly applicable to modeling transport through fractured rock masses. - External
pathways provide a mechanism by which external program modules for mass
transport (e.g., analytical, finite element or finite difference transport
models) can be directly integrated into GoldSim.
The modules are linked into GoldSim as DLLs (Dynamic Link Libraries) at run time. - Network
pathways provide a computationally efficient way to simulate large, complex
networks of one-dimensional "pipes" in order to describe mass transport through
fractured rock systems.
Network pathways require specification of a separate fracture network A complex network of one-dimensional conduits used by a Network Pathway to describe contaminant transport through fractured rock systems., which typically would be generated by a discrete fracture network generation and flow simulation code. The fracture network can be very large (100,000 pipes or more), allowing complex and realistic fracture systems to be simulated. Network pathways are only available in the RT Module.