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EGlib correction to vanishing molar concentrations #132

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EGlib correction to vanishing molar concentrations #132

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fe40ec1
EG lib correction for small molar fractions
SylvainPlessis Mar 9, 2015
faff893
verbosity added mostly,
SylvainPlessis Mar 10, 2015
d8d10d7
typo fix
SylvainPlessis Mar 12, 2015
c111960
StateType can be vectorized and might require rules to
SylvainPlessis Mar 25, 2015
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34 changes: 32 additions & 2 deletions src/diffusion/include/antioch/molecular_binary_diffusion_utils.h
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Original file line number Diff line number Diff line change
Expand Up @@ -26,10 +26,14 @@
#ifndef ANTIOCH_MOLECULAR_BINARY_DIFFUSION_UTILS_H
#define ANTIOCH_MOLECULAR_BINARY_DIFFUSION_UTILS_H

// Antioch
#include "antioch/transport_species.h"
#include "antioch/molecular_binary_diffusion_utils_decl.h"
#include "antioch/molecular_binary_diffusion_building.h"

// C++
#include <limits>

namespace Antioch
{
// getting tag
Expand Down Expand Up @@ -188,13 +192,39 @@ namespace Antioch
antioch_assert_equal_to(ds.size(),mixture.n_species());
antioch_assert_equal_to(ds.size(),mass_fractions.size());

// convenient
typedef typename value_type<VectorStateType>::type StateType;

VectorStateType molar_fractions = zero_clone(mass_fractions);
mixture.X(mixture.M(mass_fractions),mass_fractions,molar_fractions);

// EGlib traces management, see doc: http://blanche.polytechnique.fr/www.eglib/manual.ps
// page 5
// EGlib uses eps = 1e-16
typename raw_value_type<StateType>::type eps(std::numeric_limits<StateType>::epsilon() * 10);
StateType mol_frac_sum = zero_clone(mass_fractions[0]);
for(unsigned int s = 0; s < molar_fractions.size(); s++)
{
mol_frac_sum += molar_fractions[s];
}
mol_frac_sum /= (typename rebind< unsigned int, StateType >::type)(molar_fractions.size());

// (i) evaluate perturbed mole fractions
// (ii) evaluate the perturbed mean molar weight ...
StateType M_tr = zero_clone(mass_fractions[0]);
for(unsigned int s = 0; s < molar_fractions.size(); s++)
{
molar_fractions[s] += eps * (mol_frac_sum - molar_fractions[s]); // add perturbation
M_tr += molar_fractions[s] * mixture.M(s);
}


// (ii) .. evaluate perturbed mass_fraction [= molar_fraction * molar_mass / perturbed_molar_mass]
// (iii) use perturbed values to evaluate the transport properties [ (1 - y_s) / sum_i x_i / D_{is} ]
for(unsigned int s = 0; s < ds.size(); s++)
{
ds[s] = constant_clone(mass_fractions[s],1) - mass_fractions[s];
typename value_type<VectorStateType>::type denom = zero_clone(mass_fractions[0]);
ds[s] = constant_clone(mass_fractions[0],1) - mixture.M(s) / M_tr * molar_fractions[s];
StateType denom = zero_clone(mass_fractions[0]);
for(unsigned int j = 0; j < ds.size(); j++)
{
if(j == s)continue;
Expand Down