rename the phaseproperties into fluids, refactor phaseproperties.hh, so that every fluid has a file of its own.

doc/handbook/ModelDescriptions/1pboxmodel.tex

@@ -1 +1 @@
-Single phase isothermal flow model is implemented for compressible flow. \begin{align*} \phi \frac{\partial \varrho}{\partial t} + \vec{\nabla} \cdot (- \varrho \frac{\bar{\bar{K}}}{\mu} ( \nabla p -\varrho \vec{g})) = q \end{align*} However, the model can also be used for incompressible single pahse flow modeling, when in problem file a fluid with constant density is chosen. 
+Single phase isothermal flow model is implemented for compressible flow. \begin{align*} \phi \frac{\partial \varrho}{\partial t} + \vec{\nabla} \cdot (- \varrho \frac{\bar{\bar{K}}}{\mu} ( \nabla p -\varrho \vec{g})) = q \end{align*} which is discretized by this model using vertex centered finite volume (box) scheme as spatial and the implicit Euler method as time discretization. However, the model can also be used for incompressible single pahse flow modeling, when in problem file a fluid with constant density is chosen. 

doc/handbook/ModelDescriptions/2pboxmodel.tex

@@ -1,4 +1,4 @@
-This model implements two-phase flow of two completely immiscible fluids $\alpha \in \{ w, n \}$ using a standard multiphase Darcy approach as the equation for the conservation of momentum: \[ \vec{v_\alpha} = - \frac{k_{r\alpha}}{\mu_\alpha} K \left(\grad p_\alpha - \varrho_{\alpha} \boldsymbol{g} \right) \]
+This model implements two-phase flow of two completely immiscible fluids $\alpha \in \{ w, n \}$ using a standard multiphase Darcy approach as the equation for the conservation of momentum: \[ v_\alpha = - \frac{k_{r\alpha}}{\mu_\alpha} K \left(\grad p_\alpha - \varrho_{\alpha} \boldsymbol{g} \right) \]
 
 By inserting this into the equation for the conservation of the phase mass, one gets \[ \phi \frac{\partial \varrho_\alpha S_\alpha}{\partial t} - \Div \left\{ \varrho_\alpha \frac{k_{r\alpha}}{\mu_\alpha} K \left(\grad p_\alpha - \varrho_{\alpha} \boldsymbol{g} \right) \right\} = q_\alpha \;, \] which is discretized by this model using the fully-coupled vertex centered finite volume (box) scheme as spatial and the implicit Euler method as time discretization.
 

doc/handbook/ModelDescriptions/2pniboxmodel.tex

@@ -1 +1,5 @@
-This implements a non-isothermal two-phase model with Pw and Sn as primary unknowns. You can also use Pn and Sw as primary variables if you set the Formulation property to pNsW. 
+This model implements a non-isothermal two-phase flow of two completely immiscible fluids $\alpha \in \{ w, n \}$. Using the standard multiphase Darcy approach the mass conservation equations for both phases can be described as follows: \begin{eqnarray*} && \phi \frac{\partial (\sum_\alpha \varrho_\alpha S_\alpha )}{\partial t} - \sum_\alpha \Div \left\{ \varrho_\alpha \frac{k_{r\alpha}}{\mu_\alpha} \mbox{\bf K} (\grad p_\alpha - \varrho_{\alpha} \mbox{\bf g}) \right\} - \sum_\alpha q_\alpha^\kappa = \quad 0 \qquad \alpha \in \{w, n\} \end{eqnarray*} For the energy balance local thermal equilibrium is assumed which results in one energy conservation equation for the porous solid matrix and the fluids: \begin{eqnarray*} && \phi \frac{\partial \left( \sum_\alpha \varrho_\alpha u_\alpha S_\alpha \right)}{\partial t} + \left( 1 - \phi \right) \frac{\partial (\varrho_s c_s T)}{\partial t} - \sum_\alpha \Div \left\{ \varrho_\alpha h_\alpha \frac{k_{r\alpha}}{\mu_\alpha} \mathbf{K} \left( \grad \: p_\alpha - \varrho_\alpha \mathbf{g} \right) \right\} \\ &-& \Div \left( \lambda_{pm} \grad \: T \right) - q^h \qquad = \quad 0 \qquad \alpha \in \{w, n\} \end{eqnarray*}
+
+the equations are discretized by this model using the fully-coupled vertex centered finite volume (box) scheme as spatial and the implicit Euler method as time discretization.
+
+Currently the model supports chosing either $p_w$, $S_n$ and $T$ or $p_n$, $S_w$ and $T$ as primary variables. The formulation which ought to be used can be specified by setting the {\tt Formulation} property to either either {\tt \doxyref{TwoPNIIndices::pWsN}{p.}{structDune_1_1TwoPIndices_7bab78f10df58319eafe8b79a1d28553}} or {\tt \doxyref{TwoPIndices::pNsW}{p.}{structDune_1_1TwoPIndices_b2b28761c782605cf080f9b6f9b618b5}}. By default, the model uses $p_w$, $S_n$ and $T$. 

doc/handbook/ModelDescriptions/decoupled2p2c.tex

@@ -1,5 +1,5 @@
 Implementation of a decoupled formulation of a two phase two component flow processin porous media.
 
-This implementation is written for a liquid-gas system. For the physical description of gas and liquid derivations of the classes \doxyref{Gas\_\-GL}{p.}{classDune_1_1Gas__GL} and \doxyref{Liquid\_\-GL}{p.}{classDune_1_1Liquid__GL} have to be provided. The template parameters are the used grid class and the desired number type (usually double) The pressure equation is given as $ -\frac{\partial V}{\partial p}\frac{\partial p}{\partial t}+\sum_{\kappa}\frac{\partial V}{\partial m^{\kappa}}\nabla\cdot\left(\sum_{\alpha}C_{\alpha}^{\kappa}\mathbf{v}_{\alpha}\right)=\sum_{\kappa}\frac{\partial V}{\partial m^{\kappa}}q^{\kappa}$ See paper SPE 99619 for derivation. The transport equation is $ \frac{\partial C^\kappa}{\partial t} = - \nabla \cdot \sum{C_\alpha^\kappa f_\alpha {\bf v}} + q^\kappa $
+This implementation is written for a gas-liquid system with two components. An IMPES-like method is used for the sequential solution of the problem. Capillary forces and diffusion are neglected. Isothermal conditions and local thermodynamic equilibrium are assumed. Gravity is included. For the physical description of gas and liquid derivations of the classes \doxyref{Gas\_\-GL}{p.}{classDune_1_1Gas__GL} and \doxyref{Liquid\_\-GL}{p.}{classDune_1_1Liquid__GL} have to be provided. The template parameters are the used grid class and the desired number type (usually double) The pressure equation is given as \[ -\frac{\partial V}{\partial p}\frac{\partial p}{\partial t}+\sum_{\kappa}\frac{\partial V}{\partial C^{\kappa}}\nabla\cdot\left(\sum_{\alpha} {\bf v_\alpha} \varrho_\alpha X_\alpha^\kappa \right)=\sum_{\kappa}\frac{\partial V}{\partial m^{\kappa}}q^{\kappa}\] See paper SPE 99619 or \char`\"{}Analysis of a Compositional Model for Fluid Flow in Porous Media\char`\"{} by Chen, Qin and Ewing for derivation. The transport equation is \[ \frac{\partial C^\kappa}{\partial t} = - \nabla \cdot \sum{{\bf v_\alpha} \varrho_\alpha X_\alpha^\kappa} + q^\kappa \]
 
 The pressure equation is given as $ -\frac{\partial V}{\partial p}\frac{\partial p}{\partial t}+\sum_{\kappa}\frac{\partial V}{\partial m^{\kappa}}\nabla\cdot\left(\sum_{\alpha}C_{\alpha}^{\kappa}\mathbf{v}_{\alpha}\right)=\sum_{\kappa}\frac{\partial V}{\partial m^{\kappa}}q^{\kappa}$ See paper SPE 99619 for derivation. The transport equation is $ \frac{\partial C^\kappa}{\partial t} = - \nabla \cdot \sum{C_\alpha^\kappa f_\alpha {\bf v}} + q^\kappa $