A finite-volume ELLAM for three-dimensional solute-transport modeling

Area of Science:

• Environmental Science
• Hydrogeology
• Computational Science

Background:

• Ground water modeling is crucial for understanding solute transport.
• Existing methods may face limitations with advection-dominated systems.
• Accurate simulation of solute transport is essential for environmental management.

Purpose of the Study:

• To develop and implement a novel three-dimensional finite-volume ELLAM (FVELLAM) method.
• To integrate the FVELLAM as a solver option within the U.S. Geological Survey's (USGS) MODFLOW-2000.
• To evaluate the FVELLAM's performance in simulating ground water solute transport.

Main Methods:

• The FVELLAM method uses space-time finite volumes aligned with flow streamlines.
• It solves an integral form of the solute-transport equation, combining mass conservation with Eulerian-Lagrangian advantages.
• Implicit time discretization for dispersion and source/sink terms is coupled with Lagrangian advection tracking.

Main Results:

• The FVELLAM code successfully simulates advective transport, dispersion, mixing, retardation, and decay of solutes.
• It allows for large transport time increments (Courant numbers) and accurate results in advection-dominated systems (Peclet numbers).
• Testing against analytical solutions and other numerical codes shows excellent results, often with minimal time steps.

Conclusions:

• The FVELLAM method provides an effective and accurate approach for ground water solute transport simulation.
• Its implementation in MODFLOW-2000 expands the capabilities for ground water flow and transport modeling.
• The method's efficiency in handling advection-dominated systems makes it valuable for various hydrogeological applications.