Darcy Tools version 3.4. User's Guide

DarcyTools is a computer code for simulation of flow and transport in porous and/or fractured media. The fractured media in mind is a fractured rock and the porous media the soil cover on the top of the rock; it is hence groundwater flows, which is the class of flows in mind. DarcyTools is developed by a collaborative effort by SKB (The Swedish Nuclear Fuel and Waste Management Company ), MFRDC (Michel Ferry RandD Consulting) and CFE AB (Computer-aided Fluid Engineering AB). It builds upon earlier development of groundwater models, carried out by CFE during the last twenty years. In the earlier work the CFD code PHOENICS (Spalding 1981) was used as an equation solver. DarcyTools is based on a solver called MIGAL (Ferry 2002). It has however been carefully evaluated that the two solvers produce very similar solutions and the earlier work is thus still valid as a background for DarcyTools. The present report will focus on the software that constitutes DarcyTools. Two accompanying reports cover other aspects: - Concepts, Methods and Equations. (Svensson et al. 2010) (Hereafter denoted Report 1). - Verification, Validation and Demonstration (Svensson 2010) (Hereafter denoted Report 2). Two basic approaches in groundwater modelling can be identified; in one we define grid cell conductivities (sometimes called the continuum porous-medium (CPM) approach, i.e. Jackson et al. 2000), in the other we calculate the flow through the fracture network directly (DFN approach). Both approaches have their merits and drawbacks, which however will not be discussed here (for a discussion, see Sahimi 1995). In DarcyTools the two approaches are combined, meaning that we first generate a fracture network and then represent the network as grid cell properties. Further background information is given in the two reports mentioned.