The simplest application of a Pipe pathway A transport pathway element that is intended to represent a feature that essentially behaves as a fluid conduit, such as a fracture. Pipes are primarily used for simualting matrix diffusion in fractured groundwater pathways. is to use it to simulate one-dimensional advective-dispersive transport.
The first step in defining a Pipe pathway is to specify its geometry. The geometry of a Pipe is defined by specifying a length, a cross-sectional area, and a perimeter.
You then specify the flow rate of 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). in the pathway (by defining one or more advective mass flux links from the pathway) and a dispersivity. The velocity in the pathway is computed as a function of the flow rate, the cross-sectional area, a user-specified saturation level, and the porosity of the porous medium (if any) which is specified to fill the pathway.
GoldSim then solves the one-dimensional advection-dispersion equation analytically to compute flux rates exiting the pathway. Pipes explicitly represent the decay of 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). as they flow through the pathway, as well as the ingrowth of daughter products from parent species. Parents and daughters Reaction products of a species. Species can decay into one or more daughters (or daughter products). can have completely different transport properties which will be explicitly represented within the pathway.
Two types of linear retardation processes can be represented within a Pipe:
- equilibrium partitioning between the fluid in the pathway and an infill material; and
- equilibrium partitioning between the fluid in the pathway and a coating material around the perimeter of the pathway (which would typically be applicable only if the Pipe was being used to simulate transport through a fracture).
If you wish to simulate retardation due to partitioning onto an infill material, you must specify a porous Solid medium to represent the infill. Similarly, if you wish to simulate retardation due to partitioning onto a coating material, you must specify a Solid medium to represent the coating (which can be different from the infill medium), and a coating thickness. Fluid within the pore volume of the coating material is assumed to be immobile.
The mobile fluid in the pore volume of the pathway, the immobile fluid within the coating material, the infill material and the coating material are all assumed to be at equilibrium at all times. The effective retardation factor is therefore computed as a function of the properties of the infill and coating 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. (bulk densities, porosities, and partition coefficients) and the geometry of the pathway (saturation level, cross-sectional area and perimeter).
- Advective-Dispersive Transport in Pipes
- Comparing Pipes and Aquifers
- Computing Pipe and Aquifer Pathway Concentrations Accounting for Transverse Dispersion
- Controlling the Pipe Solution Algorithm
- Defining a Sorptive Coating Material for a Pipe
- Defining Basic Pipe Properties
- Features and Capabilities of Pipes
- Flux Links to/from Pipes
- Pipe Pathway Outputs
- Saving Results for a Pipe
- Simulating Storage Zones in a Pipe
- Simulating Suspended Solids in a Pipe
- Simulating Time-Variable Pipe Properties
- Summary of Limitations on the Use of Pipe Pathways
- Viewing a Pipe in the Browser