Modeling tools

Modeling tools

The following list shows some selected modeling tools that can be used for the simulation of fracture flow and transport. Their capabilities with respect to modeling flow and transport in fractured media are compared in the chapter Comparison of capabilities .

COMSOL Multiphysics

COMSOL Multiphysics® is a comprehensive modeling suite that can be used for computeing flow and transport in limestone aquifers. It provides predefined physics-based interfaces (e.g. a module for subsurface flow) and allows equation-based modeling, where arbitrary partial differential equations can be solved. Different physics can be coupled. The toolbox provides tools for mesh generation, a user interface for the simulation setup, several solvers and visualization and post-processing tools.

Discretization methods etc.

For the modeling of fracture flow, there is a physics interface available. We show a way to include discrete fracture flow and transport using the feature called "Weak contributions". Instructions for setting up a discrete-fracture model in COMSOL Multiphysics (PDF)

More details can be found on the COMSOL webpage:

• Comsol Multiphysics

FEFlow

FEFlow is a finite-element based simluator for groundwater flow, contaminant, groundwater age and heat transport simulations.

• FEFlow

Hydrogeosphere

• HydroGeoSphere

Comparison of capabilities

Useful helpers

Besides the comprehensive models, there are several small tools available that can be helpful when dealing with contaminant transport in limestone aquifers. Some will be described in the following.

Matlab model based on the semi-analytical algorithm presented in Christ and Goltz, 2002

Contaminated sites can often pose a threat to water suppliers. Christ and Goltz have developed a semi-analytical algorithm that allows estimating the capture zones of extraction wells. We have set up a simple Matlab model based on the algorithm from Christ and Goltz, which requires only a few parameters to estimate the capture zone of a production well. This can be very useful to get a quick estimate, if a contaminant is likely to flow towards a drinking water well, for example.

Required parameters

Following parameters are required to set up and run the model:

• Estimate of the hydraulic conductivity
• Average hydraulic gradient of the natural groundwater flow
• Reference head at one point in the domain
• Direction of natural groundwater flow
• Aquifer thickness
• Location of wells
• Pumping rates of the wells in the study area

The model computes streamlines and isopotentials for the given parameters. When a background map of the study area is specified, the streamlines and isopotential lines are directly plotted on the map, as shown in the example below.

Example of a capture zone calculation for a field site in Hedehusene. The blue lines are calculated streamlines and the blue lines are isopotentials.

The semi-analytical solution is described in the paper by Christ and Goltz, J. Hydrology, 2002, p. 224-244. [1].

A Matlab example file can be seen here: Matlab model for capture zone calculation

The example including the background map shown above can be downloaded as zipfile here: Download Matlab model

Aqtesolv

Aqtesolv is an easy-to-use tool for the design and interpretation of aquifer tests like pump tests and slug tests. It provides a bunch of conventional aquifer models for confined, leaky confined and unconfined aquifers and several advanced models, e.g. for fractured aquifers or oscillating water tables. A comprehensive description of the capabilities and a free demo version is available on the software's web page.

• Aqtesolv

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