A Network Pathway A transport pathway element that provides a computationally efficient way to simulate large, complex networks of one-dimensional conduits in order to describe contaminant transport through fractured rock systems. is made up of multiple "pipes". The fact that these are referred to as pipes is not coincidental - each fracture network A complex network of one-dimensional conduits used by a Network Pathway to describe contaminant transport through fractured rock systems. pipe has all the features and capabilities of the Pipe pathways discussed previously. In fact, Network pathways are effectively large collections of Pipe pathways. Like Pipe pathways, Network pathways contain only a single fluid medium (which is always, by definition, the Reference Fluid A special type of Fluid element that provides a basis for defining partition coefficients between media for the various species in the model (i.e., the ratio of the species’ concentration in the medium to its concentration in the Reference Fluid at equilibrium).).
Network Pathways require specification of a
In addition, for each pipe in the fracture network, a
Warning: Solubility constraints are not applied within Network pathways. (They are only applied within Cells and Aquifers). Hence, if the concentration of a 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). entering a Network pathway (e.g., via a boundary condition) exceeded the solubility limit, the concentration leaving the Network could exceed the solubility limit.
A schematic of a relatively small three-dimensional fracture network that could be simulated by GoldSim is shown below:
In addition to defining the fracture network, it is necessary to identify the mass flux links to and from the Network pathway (referred to as "sources" and "sinks", respectively), and specify the properties for all of the fracture sets referenced by the fracture network. Although there may be a very large number of "pipes" (100,000 or more), it is assumed that these can all be grouped into a relatively small (typically ten or less) number of fracture sets.
To facilitate representation of uncertainty in the fracture network connectivity and flow properties, you have the option to define a number of separate fracture networks and instruct GoldSim to randomly select one of these every realization A single model run within a Monte Carlo simulation. It represents one possible path the system could follow through time..
The ability to solve Network pathways efficiently results from the fact that it is possible to develop a Laplace-transformed transfer matrix for an entire network of Pipe pathways by simple additions and multiplications of the transformed transfer matrices for each individual pathway. Once the network transfer matrix/matrices are developed, then the transport calculations for the network are no more time-consuming than for a single Pipe pathway. The only extra computational expense is the time required for the creation of the network transfer matrix at the beginning of the simulation. For even quite large networks (100,000 pipes or more), this time is not excessive.
The mathematical details of Network pathways are discussed
in
- Controlling the Network Pathway Solution Algorithm
- Defining Fracture Sets
- Defining Network Pathway Properties
- Features and Capabilities of Network Pathways
- Flux Links to/from Network Pathways
- Mass Balance in a Network Pathway
- Network Pathway Outputs
- Saving Results for a Network Pathway
- Summary of Limitations on the Use of Network Pathways
- Viewing a Network Pathway in the Browser