Ewoms::FlashModel< TypeTag > Class Template Reference

A compositional multi-phase model based on flash-calculations. More...

#include <flashmodel.hh>

Inheritance diagram for Ewoms::FlashModel< TypeTag >:
Ewoms::MultiPhaseBaseModel< TypeTag >

Public Member Functions

 FlashModel (Simulator &simulator)
 
std::string primaryVarName (unsigned pvIdx) const
 Given an primary variable index, return a human readable name. More...
 
std::string eqName (unsigned eqIdx) const
 Given an equation index, return a human readable name. More...
 
Scalar primaryVarWeight (unsigned globalDofIdx, unsigned pvIdx) const
 Returns the relative weight of a primary variable for calculating relative errors. More...
 
Scalar eqWeight (unsigned globalDofIdx, unsigned eqIdx) const
 Returns the relative weight of an equation. More...
 
void registerOutputModules_ ()
 
- Public Member Functions inherited from Ewoms::MultiPhaseBaseModel< TypeTag >
 MultiPhaseBaseModel (Simulator &simulator)
 
void finishInit ()
 Apply the initial conditions to the model. More...
 
bool phaseIsConsidered (unsigned phaseIdx OPM_UNUSED) const
 Returns true iff a fluid phase is used by the model. More...
 
void globalPhaseStorage (EqVector &storage, unsigned phaseIdx)
 Compute the total storage inside one phase of all conservation quantities. More...
 
void registerOutputModules_ ()
 

Static Public Member Functions

static void registerParameters ()
 Register all run-time parameters for the immiscible model.
 
static std::string name ()
 
- Static Public Member Functions inherited from Ewoms::MultiPhaseBaseModel< TypeTag >
static void registerParameters ()
 Register all run-time parameters for the immiscible model.
 

Detailed Description

template<class TypeTag>
class Ewoms::FlashModel< TypeTag >

A compositional multi-phase model based on flash-calculations.

This model assumes a flow of $M \geq 1$ fluid phases $\alpha$, each of which is assumed to be a mixture $N \geq M$ chemical species (denoted by the upper index $\kappa$).

By default, the standard multi-phase Darcy approach is used to determine the velocity, i.e.

\[ \mathbf{v}_\alpha = - \frac{k_{r\alpha}}{\mu_\alpha} \mathbf{K} \left(\mathbf{grad}\, p_\alpha - \varrho_{\alpha} \mathbf{g} \right) \;, \]

although the actual approach which is used can be specified via the FluxModule property. For example, the velocity model can by changed to the Forchheimer approach by

The core of the model is the conservation mass of each component by means of the equation

\[ \sum_\alpha \frac{\partial\;\phi c_\alpha^\kappa S_\alpha }{\partial t} - \sum_\alpha \mathrm{div} \left\{ c_\alpha^\kappa \mathbf{v}_\alpha \right\} - q^\kappa = 0 \;. \]

To determine the quanties that occur in the equations above, this model uses flash calculations. A flash solver starts with the total mass or molar mass per volume for each component and, calculates the compositions, saturations and pressures of all phases at a given temperature. For this the flash solver has to use some model assumptions internally. (Often these are the same primary variable switching or NCP assumptions as used by the other fully implicit compositional multi-phase models provided by eWoms.)

Using flash calculations for the flow model has some disadvantages:

  • The accuracy of the flash solver needs to be sufficient to calculate the parital derivatives using numerical differentiation which are required for the Newton scheme.
  • Flash calculations tend to be quite computationally expensive and are often numerically unstable.

It is thus adviced to increase the target tolerance of the Newton scheme or a to use type for scalar values which exhibits higher precision than the standard double (e.g. quad) if this model ought to be used.

The model uses the following primary variables:

  • The total molar concentration of each component: $c^\kappa = \sum_\alpha S_\alpha x_\alpha^\kappa \rho_{mol, \alpha}$
  • The absolute temperature $T$ in Kelvins if the energy equation enabled.

Member Function Documentation

◆ eqName()

template<class TypeTag >
std::string Ewoms::FlashModel< TypeTag >::eqName ( unsigned  eqIdx) const
inline

Given an equation index, return a human readable name.

Parameters
eqIdxThe index of the conservation equation of interest.

◆ eqWeight()

template<class TypeTag >
Scalar Ewoms::FlashModel< TypeTag >::eqWeight ( unsigned  globalDofIdx,
unsigned  eqIdx 
) const
inline

Returns the relative weight of an equation.

Parameters
globalVertexIdxThe global index of the vertex
eqIdxThe index of the equation

◆ name()

template<class TypeTag >
static std::string Ewoms::FlashModel< TypeTag >::name ( )
inlinestatic

◆ primaryVarName()

template<class TypeTag >
std::string Ewoms::FlashModel< TypeTag >::primaryVarName ( unsigned  pvIdx) const
inline

Given an primary variable index, return a human readable name.

Parameters
pvIdxThe index of the primary variable of interest.

◆ primaryVarWeight()

template<class TypeTag >
Scalar Ewoms::FlashModel< TypeTag >::primaryVarWeight ( unsigned  globalDofIdx,
unsigned  pvIdx 
) const
inline

Returns the relative weight of a primary variable for calculating relative errors.

Parameters
globalDofIdxThe global index of the degree of freedom
pvIdxThe index of the primary variable

The documentation for this class was generated from the following file: