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Fix to getDiffusion in order to avoid a NAN result for m_nsp = 1 case

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and for mixtures with X_i=1.0.
This commit is contained in:
Harry Moffat 2003-12-20 18:03:56 +00:00
parent 151d278a48
commit 0da002eeb1
1 changed files with 23 additions and 8 deletions
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31
Cantera/src/transport/MixTransport.cpp
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@ -264,7 +264,14 @@ namespace Cantera {
}
}
/**
* Mixture-averaged diffusion coefficients [m^2/s].
*
* For the single species case or the pure fluid case
* the routine returns the self-diffusion coefficient.
* This is need to avoid a Nan result in the formula
* below.
*/
void MixTransport::getMixDiffCoeffs(doublereal* d) {
update_T();
@ -277,16 +284,24 @@ namespace Cantera {
doublereal mmw = m_thermo->meanMolecularWeight();
doublereal sumxw = 0.0, sum2;
doublereal p = pressure_ig();
for (k = 0; k < m_nsp; k++) sumxw += m_molefracs[k] * m_mw[k];
for (k = 0; k < m_nsp; k++) {
if (m_nsp == 1) {
d[0] = m_bdiff(0,0) / p;
} else {
for (k = 0; k < m_nsp; k++) sumxw += m_molefracs[k] * m_mw[k];
for (k = 0; k < m_nsp; k++) {
sum2 = 0.0;
for (j = 0; j < m_nsp; j++) {
if (j != k) {
sum2 += m_molefracs[j] / m_bdiff(j,k);
}
if (j != k) {
sum2 += m_molefracs[j] / m_bdiff(j,k);
}
}
d[k] = (sumxw - m_molefracs[k] * m_mw[k])/(p * mmw * sum2);
}
if (sum2 <= 0.0) {
d[k] = m_bdiff(k,k) / p;
} else {
d[k] = (sumxw - m_molefracs[k] * m_mw[k])/(p * mmw * sum2);
}
}
}
}