How do I know which module I need?
Each Equation-of-State (EOS) module describes the thermophysical properties of specific combinations of phases and components. The user has to decide which are the components (e.g., water, CO2) of interest for a given application. One should also consider the range of pressure and temperature covered by an EOS module. Finally, check whether you need to be able to handle special processes, or whether you need inverse modeling capabilities, etc. Refer to the licensing page for available modules, and consult the related documentation, e.g., Section 6 of the TOUGH2 User’s Guide.
What does the core module do?
The TOUGH2, TOUGH2-MP, TOUGH+, and iTOUGH2 suites of simulators require the user to obtain a core module plus one or more EOS modules (and potentially additional modules with special capabilities). The TOUGH2, TOUGH2-MP, and TOUGH+ core modules contain general-purpose subroutines that read input, assemble mass and energy balance equations, solve sets of linear equations, etc. The iTOUGH2 core module contains the TOUGH2 core module, various optimization algorithms, and routines that perform the error and uncertainty analysis. While the user needs to purchase the respective core module, the core module by itself is not executable — it has to be linked to an EOS module, which calculates thermophysical properties and performs phase diagnostics for the phases and components of interest. (Similarly, an EOS module by itself is not executable, i.e., it needs to be linked to the core module.) Various EOS modules can be linked to the same core module, albeit only one at a time, resulting in separate executables for each phase- and component-specific simulator. Refer to the licensing page for available modules, and check whether a core module needs to be purchased.