SWIFT-98 DESCRIPTION

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Three-Dimensional Groundwater Flow and Transport

Pressure, Temperature, Brine, Radionuclides

PC Interface

Dual Porosity and Fractured Media

Introduction to SWIFT
SWIFT Features
SWIFT Basic Assumptions
SWIFT Method of Solution
SWIFT Equations
SWIFT Boundary Conditions
SWIFT Typical Applications
SWIFT Postprocessing
SWIFT STLINE Particle Tracking
SWIFT Runtime Monitor
SWIFT Basic Package
SWIFT Requirements
 

  • Three-dimensional groundwater flow and transport
  • Pressure, temperature, brine, radionuclides
  • PC Interface
  • Dual porosity and fractured media

INTRODUCTION TO SWIFT

SWIFT - 98 is a fully transient, three-dimensional model which simulates the flow and transport of fluid, heat (energy), brine, and radio nuclide chains in porous and fractured geologic media. The primary equations for fluid, heat, and brine are coupled with fluid density, fluid viscosity, and porosity. Steady-state options are available for the fluid and brine equations, and both Cartesian and cylindrical coordinate systems may be used. However, the latter system is restricted to two-dimensional, r-z simulations. Both dual-porosity and discrete-fracture conceptualizations may be considered for the fractured zone. Migration within the rock matrix is characterized as a one-dimensional process.

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SWIFT FEATURES

  • A run-time monitor displays the simulation progress, convergence, mass balance, and dialog.
  • Versatile interface to SURFER for contouring pressure, temperature and concentration.
  • Extensive error checking.
  • Auxiliary files for variable structure grid, restart, mapping, mass balance, well summary and concentration discharge.
  • STLINE code for particle tracking.
  • Easy installation, 70 verification QA/QC data sets.

SWIFT BASIC ASSUMPTIONS AND CHARACTERISTICS

  • Single-phase fluid flow governed by Darcy's law
  • Three-dimensional transport in the global system, and one-dimensional transport in the local rock matrix subsystem
  • Local rock matrix may be characterized by either prisms or spheres
  • Linear variations in porosity and fluid density with respect to the dependent variables
  • Viscosity is dependent on temperature and brine concentrations only
  • Nonlinear isothermal equilibrium adsorption (Freundlich or linear)
  • Injection wastes are miscible with the resident fluids
  • Confined or unconfined aquifer (transient or steady-state free water surface)
  • Hydraulic and thermal conductivities may be heterogeneous and/or anisotropic
  • Longitudinal and transverse dispersivities may vary throughout the domain
  • Variable rock compressibility (storativity)
  • Dual or simultaneous discretization

SWIFT METHOD OF SOLUTION

Discretization is performed by the finite-difference method using centered or backward weighting in the time and space domains. Matrix solution is performed either by Gaussian elimination or by two-line successive overrelaxation.

SWIFT EQUATIONS

SWIFT comprises the four transport processes: fluid, heat, brine and radionuclide chains. For porous media, only the global (three-dimensional) process simulator is used. For fractured media, the global process simulator is used for the fractured media, and the local (one-dimensional) process simulator is used for the rock matrix.

SWIFT BOUNDARY CONDITIONS

A variety of boundary conditions and source terms may be invoked for both the porous and fractured media. These include:

  • Prescribed pressure (head), temperature, and brine concentration
  • Prescribed flux of fluid (water), heat, brine, or nuclide mass
  • Wellbore injection/production submodel subject to pumping constraints
  • Aquifer influence function (i.e., Carter-Tracy infinite reservoir)
  • Dual porosity domain extension
  • Waste-leach radionuclide submodel for waste repository nuclides and heat
  • Freewater surface with recharge

SWIFT TYPICAL APPLICATIONS

SWIFT can be applied to a variety of groundwater problems ranging from simple well flow to complex transport analysis.

  • Deep well injection of hazardous waste, isothermal/nonisothermal, constant/variable density
  • Hazardous waste site characterization and remediation (RI/FS)
  • Pump-and-treat, hydraulic containment and other waste remediation
  • Saltwater intrusion, upconing
  • Aquifer thermal energy storage
  • High-level radioactive waste performance assessment
  • Fractured media, dual porosity

SWIFT POSTPROCESSING

Postprocessor Interface (UNSWIFT) - Contour maps of pressure, temperature, brine, or concentration in any window in any plane can be quickly processed directly into uniformly-spaced grid files for the SURFER contouring software.

SWIFT STLINE PARTICLE TRACKING

Allows transient flowpath evaluation of streamlines and export to SURFER as lines or posted symbols.

SWIFT RUNTIME MONITOR

The runtime monitor displays essential simulation data on a conventional PC monitor using standard ANSI characters. The monitor tracks the simulation progress, highlighting the current program activity at the base of the screen. The time step, interval and other data are updated on the screen through the course of the simulation. Below the frame, system RAM requirements, matrix convergence (L2SOR only), creation of map file, and error messages are displayed. Auxiliary files for restart or binary input are also prompted.

SWIFT BASIC PACKAGE

  • SWIFT Data Input Guide
  • SWIFT and SWIFT II documents (4 publicly available NTIS reports)
  • All FORTRAN source code and 70 verification problem input and output data sets on diskettes

With sufficient memory resources, SWIFT can be used to model complex field applications at a reasonable price. SWIFT users can choose either support or nonsupported. Optional training is available.

SWIFT Requirements: Pentium with 32 MB RAM and Lahey LF90 Version 4.5 compiler, and Surfer for postprocessing graphics.