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LangmuirHinshelwoodReactionRate: Added support for arbitrary powers of concentration in the denominator

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and the "1" constant in the denominator is now an optional input to provide
greater flexibility of the model.
This commit is contained in:
Henry Weller
2018-08-13 16:10:14 +01:00
parent c3c09229be
commit 9a437d5743
2 changed files with 42 additions and 38 deletions
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15
src/thermophysicalModels/specie/reaction/reactionRate/LangmuirHinshelwood/LangmuirHinshelwoodReactionRate.H
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@ -68,15 +68,16 @@ class LangmuirHinshelwoodReactionRate
//- List of species present in reaction system
const speciesTable& species_;
static const label n_ = 3;
scalar A_[n_];
scalar Ta_[n_];
//- Reactant names
FixedList<word, 2> reactantNames_;
//- Index of specie "A"
label a_;
//- Reactant indices
FixedList<label, 3> r_;
//- Index of specie "B"
label b_;
scalar a_;
FixedList<scalar, 3> A_;
FixedList<scalar, 3> Ta_;
FixedList<scalar, 3> m_;
public:

65
src/thermophysicalModels/specie/reaction/reactionRate/LangmuirHinshelwood/LangmuirHinshelwoodReactionRateI.H
View File

@ -35,16 +35,22 @@ inline Foam::LangmuirHinshelwoodReactionRate::LangmuirHinshelwoodReactionRate
)
:
species_(st),
a_(st[dict.lookup("A")]),
b_(st[dict.lookup("B")])
reactantNames_(dict.lookup("reactants")),
a_(dict.lookupOrDefault<scalar>("a", 1)),
A_(dict.lookup("A")),
Ta_(dict.lookup("Ta")),
m_
(
dict.lookupOrDefault<FixedList<scalar, 3>>
(
"m",
FixedList<scalar, 3>({1, 1, 2})
)
)
{
// Read (A, Ta) pairs
FixedList<Tuple2<scalar, scalar>, n_> coeffs(dict.lookup("coeffs"));
forAll(coeffs, i)
forAll(reactantNames_, i)
{
A_[i] = coeffs[i].first();
Ta_[i] = coeffs[i].second();
r_[i] = st[reactantNames_[i]];
}
}
@ -58,9 +64,12 @@ inline Foam::scalar Foam::LangmuirHinshelwoodReactionRate::operator()
const scalarField& c
) const
{
const scalar c0m = pow(c[r_[0]], m_[0]);
const scalar c1m = pow(c[r_[1]], m_[1]);
return A_[0]*exp(-Ta_[0]/T)/
(
T*sqr(1 + A_[1]*exp(-Ta_[1]/T)*c[a_] + A_[2]*exp(-Ta_[2]/T)*c[b_])
T*pow(a_ + A_[1]*exp(-Ta_[1]/T)*c0m + A_[2]*exp(-Ta_[2]/T)*c1m, m_[2])
);
}
@ -72,20 +81,20 @@ inline Foam::scalar Foam::LangmuirHinshelwoodReactionRate::ddT
const scalarField& c
) const
{
const scalar den =
(
T*sqr(1 + A_[1]*exp(-Ta_[1]/T)*c[a_] + A_[2]*exp(-Ta_[2]/T)*c[b_])
);
const scalar c0m = pow(c[r_[0]], m_[0]);
const scalar c1m = pow(c[r_[1]], m_[1]);
const scalar dr0 = A_[1]*exp(-Ta_[1]/T)*c0m;
const scalar dr1 = A_[2]*exp(-Ta_[2]/T)*c1m;
const scalar denByT = pow(a_ + dr0 + dr1, m_[2]);
const scalar den = T*denByT;
const scalar rate = A_[0]*exp(-Ta_[0]/T)/den;
const scalar derivDen =
(
sqr(1 + A_[1]*exp(-Ta_[1]/T)*c[a_] + A_[2]*exp(-Ta_[2]/T)*c[b_])
+ 2*T*(1 + A_[1]*exp(-Ta_[1]/T)*c[a_] + A_[2]*exp(-Ta_[2]/T)*c[b_])
*(
A_[1]*exp(-Ta_[1]/T)*c[a_]*Ta_[1]/sqr(T)
+ A_[2]*exp(-Ta_[2]/T)*c[b_]*Ta_[2]/sqr(T)
)
denByT
+ m_[2]*T*(a_ + dr0 + dr1)*(dr0*Ta_[1]/sqr(T) + dr1*Ta_[2]/sqr(T))
);
return rate*(Ta_[0]/sqr(T) - derivDen/den);
@ -122,18 +131,12 @@ inline Foam::scalar Foam::LangmuirHinshelwoodReactionRate::dcidT
inline void Foam::LangmuirHinshelwoodReactionRate::write(Ostream& os) const
{
os.writeKeyword("A") << species_[a_] << token::END_STATEMENT << nl;
os.writeKeyword("B") << species_[b_] << token::END_STATEMENT << nl;
FixedList<Tuple2<scalar, scalar>, n_> coeffs;
forAll(coeffs, i)
{
coeffs[i].first() = A_[i];
coeffs[i].second() = Ta_[i];
}
os.writeKeyword("coeffs") << coeffs << nl;
os.writeKeyword("reactants")
<< reactantNames_ << token::END_STATEMENT << nl;
os.writeKeyword("a") << a_ << token::END_STATEMENT << nl;
os.writeKeyword("A") << A_ << token::END_STATEMENT << nl;
os.writeKeyword("Ta") << Ta_ << token::END_STATEMENT << nl;
os.writeKeyword("m") << m_ << token::END_STATEMENT << nl;
}