materialsystem.md

---
title: Material system
---

# Introduction to DuMuX- Material system

## Challenges in simulating porous media:

* Highly heterogeneous distribution of parameters and complex nonlinear material laws

* Strong interconnection of properties **--->** difficult to achieve modularity

## Modular structure:

<ins> User-defined parameters and relationships: </ins>

* Components
* Fluid system
* Solid system
* Binary coefficients
* Fluid-matrix interactions
* Chemistry
* Equation of state (Eos)

## <ins> Dumux-specific containers and solvers </ins>

- Fluid states
- Solid states
- Constraint solvers

# Material system: Component

## Component

<img src="img/component.png" width="200"/>

## <ins> What it does: </ins>

* **Thermodynamic relations** (e.g. molar mass, vapor pressure, density) of a **single chemical species** or a fixed mixture of species
* Provide a convenient way to access these quantities
* Not supposed to be used by models directly

## <ins> Example implementations: </ins>

* _H2O_ : pure water, properties by IAPWS-97 or simplified

* _Brine_ : water with a given salt concentration

# Material system: Fluid system

## Fluid system

<img src="img/fluidsystem.png" width="300"/>

## <ins> What it does: </ins>

* Expresses the **thermodynamic relations between fluid quantities** (e.g. calculation of density or viscosity based on composition, fugacity coefficient based on temperature and pressure...)
* Stateless classes (all member functions are static)

## <ins> Example implementations: </ins>

* _TwoPImmiscible_ : two immiscible fluid phases

* _H2OAir_ : gas and liquid phase with components water and air

# Material system: Binary coefficients

## Binary coefficients

<img src="img/binarycoefficients.png" width="350"/>

## <ins> What it does: </ins>

  **Contains** data required for binary mixtures (e.g. binary diffusion coefficients, coefficients needed for constitutive relationships (like Henry coefficient))

## <ins> Example implementations: </ins>

* _H2O_Air_

* _Brine_CO2_

# Material system: Solid system

## Solid system

<img src="img/solidsystem.png" width="300"/>

## <ins> What it does: </ins>

* Expresses the **thermodynamic properties of the solid matrix** (e.g. calculation of the solid density and solid heat capacity based on the composition...)
* Stateless classes (all member functions are static)

## <ins> Implementations: </ins>

* _OneCSolid_ : inert solid matrix of one solid component (e.g. granite)
* _CompositionalSolidPhase_ : composed solid matrix of inert or reactive components (e.g. NaCl and granite)

# Material system: Fluid-matrix interactions

## Fluid-materix interactions

<img src="img/fluidmatrixinteractions.png" width="250"/>

## <ins> What it does: </ins>

* Description of the **interaction of the fluid phases with the porous medium** (e.g. capillary pressure and relative permeability relationships)
* Through modular adapters, regularization schemes can be imposed for extreme values

## <ins> Example implementations: </ins>

* _VanGenuchten_

* _BrooksCorey_

# Material system: Chemistry

## Chemistry

<img src="img/chemistry.png" width="200"/>

## <ins> What it does: </ins>

* Expresses the **electrochemical models for a fuel cell application** (e.g. calculattion of reaction sources with an electrochemical model approach)
* Stateless classes (all member functions are static)

## <ins> Example implementations: </ins>

* _Electrochemistry_ : for isothermal system
* _Electrochemistryni_ : for non-isothermal system

# Material system: Equation of state

## Equation of state

<img src="img/eos.png" width="250"/>

## <ins> What it does: </ins>

* Implements the **equation of state** for liquids and gases, and also for mixture (e.g. compute vapor pressure, molar volume, etc.)
* Stateless classes (all member functions are static)

## <ins> Example implementations: </ins>

* _Pengrobinson_ : eos for liquid and gas
* _Pengrobinsonmixture_ : eos for a mixture



# Material system: Fluid state

## Fluid state

<img src="img/fluidstate.png" width="800"/>

## <ins> What it does: </ins>

 * **Stores** the complete thermodynamic configuration of a system at a given spatial and temporal position (e.g. saturation, mole fraction, enthalpy)
 * **Provides access** methods to all thermodynamic quantities (e.g. saturation, mole fraction, enthalpy)

## <ins> Example implementations: </ins>

 * _ImmiscibleFluidState_: assumes immiscibility of the fluid phases. Phase compositions and fugacity coefficients do not need to be stored explicitly
 * _CompositionalFluidState_: assumes thermodynamic equilibrium, only a single temperature needs to be stored

# Material system: Solid state

## Solid state

<img src="img/solidstate.png" width="800"/>

## <ins> What it does: </ins>

 * **Stores** the complete solid configuration of a system at a given spatial and temporal position (e.g. solid volume fractions, solid heat capacity)
 * **Provides** access methods to all solid quantities (e.g. porosity, density, temperature)

## <ins> Example implementations: </ins>

* _InertSolidState_: assumes an inert solid phase. Solid volume fractions do not change

* _CompositionalSolidState_: assumes a solid matrix composed out of two components. The volume fractions can change and properties such as heat capacity are adapted

# Material system: Constraint Solver

## Constraint solver

<img src="img/constraintsolver.png" width="1000"/>

## <ins> What it does: </ins>

**Connects** the thermodynamic relations expressed by fluid systems with the thermodynamic quantities stored by fluid states (e.g. mole fraction, density)

## <ins> Example implementation: </ins>

CompositionFromFugacities: takes all component fugacities, the temperature and pressure of a phase as input and calculates the phase composition

# Example: From component to fluid system

## Component ---> fluid system

<img src="img/component-fluidsystem.png" width="500"/>

## Example: 2 phases, miscible

 * Components: _H2O_, _Air_
 * Fluid system: _TwoPTwoC_

## Include headers in properties file: components

```cpp
// The two-phase immiscible fluid system
#include <dumux/material/fluidsystems/h2oair.hh>
// The water component
#include <dumux/material/components/h2o.hh>
// The air component
#include <dumux/material/components/air.hh>
```

## Specify fluid system in properties file:

```cpp

template<class TypeTag>
struct FluidSystem<TypeTag, TTag::H2OAir>
{
private:
    using Scalar = GetPropType<TypeTag, Properties::Scalar>;
public:
    using type = FluidSystems::H2OAir<Scalar,
                 Components::TabulatedComponent<Components::H2O<Scalar>>,
                 FluidSystems::H2OAirDefaultPolicy</*fastButSimplifiedRelations=*/true>,
                 true /*useKelvinEquation*/>;
};
```


# Example: From component to solid system

## Example: 2 phases, miscible

 * Components: _CaO_, _CaO2H2_ (slaked lime)
 * Solid system: _OnePNCMin_

## Specify solid system in properties file:

```cpp
// The solid system
template<class TypeTag>
struct SolidSystem<TypeTag, TTag::ThermoChem>
{
    using Scalar = GetPropType<TypeTag, Properties::Scalar>;
    using ComponentOne = Components::ModifiedCaO<Scalar>;
    using ComponentTwo = Components::CaO2H2<Scalar>;
    using type = SolidSystems::CompositionalSolidPhase<Scalar, ComponentOne, ComponentTwo>;
};
```
## Note to solid system

Specifying a solid system is only necessary if you work with a non-isothermal or mineralization model. If no solid system is specified in the problem file, the default is the inert solid phase with the constant component. For the constant component you can set properties in the input file.


# Exercise

## <ins> Tasks: </ins>

1. Get familiar with the code
2. 2p model: Implement a new component (incompressible and compressible)
3. 2p2c model: Implement a new fluid system
4. Change wettability of the porous medium
5. Advanced: Use van Genuchten relationship with parameters: alpha = 0.0037 and alphalense = 0.00045, n = 4.7 and nlense = 7.3

**First step:** Go to <https://git.iws.uni-stuttgart.de/dumux-repositories/dumux-course/tree/master/exercises/exercise-fluidsystem> and check out the README