In \Dumux two sorts of models are implemented: Fully-coupled models and decoupled models. In the fully-coupled models a flow system is described by a system of strongly coupled equations which can be mass balance equations, balance equations of components, energy balance equations, etc. In contrast a decoupled model consists of a pressure equation which is iteratively coupled to a saturation equation, concentration equations, energy balance equations, etc.
Examples for different kinds of both coupled and decoupled models are isothermal two-phase models, isothermal two-phase two-component models, non-isothermal two-phase models, non-isothermal two-phase two-component models, etc.
The following two sections of the tutorial demonstrate how to solve problems first using a coupled model (section \ref{tutorial-coupled}) and second using a decoupled model (section \ref{tutorial-decoupled}). Being the easiest case, a isothermal two-phase system (two fluid phases, one solid phase) will be considered.
