Added diffusion velocity returns to SimpleTransport.
Worked on documentation.
This commit is contained in:
Harry Moffat
parent
cc0b37123e
commit
f59c07606a
3 changed files with 224 additions and 11 deletions
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@ -482,8 +482,7 @@ namespace Cantera {
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doublereal* current);
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//! Get the species diffusive velocities wrt to
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//! the averaged velocity,
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//! Get the species diffusive velocities wrt to the averaged velocity,
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//! given the gradients in mole fraction and temperature
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/*!
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* The average velocity can be computed on a mole-weighted
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@ -598,6 +598,104 @@ namespace Cantera {
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dt[k] = 0.0;
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}
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}
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//====================================================================================================================
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//! Get the species diffusive velocities wrt to the averaged velocity,
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//! given the gradients in mole fraction and temperature
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/*!
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* The average velocity can be computed on a mole-weighted
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* or mass-weighted basis, or the diffusion velocities may
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* be specified as relative to a specific species (i.e. a
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* solvent) all according to the velocityBasis input parameter.
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*
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* Units for the returned velocities are m s-1.
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*
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* @param ndim Number of dimensions in the flux expressions
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* @param grad_T Gradient of the temperature
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* (length = ndim)
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* @param ldx Leading dimension of the grad_X array
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* (usually equal to m_nsp but not always)
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* @param grad_X Gradients of the mole fraction
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* Flat vector with the m_nsp in the inner loop.
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* length = ldx * ndim
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* @param ldf Leading dimension of the fluxes array
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* (usually equal to m_nsp but not always)
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* @param Vdiff Output of the diffusive velocities.
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* Flat vector with the m_nsp in the inner loop.
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* length = ldx * ndim
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*/
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void SimpleTransport::getSpeciesVdiff(int ndim,
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const doublereal* grad_T,
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int ldx,
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const doublereal* grad_X,
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int ldf,
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doublereal* Vdiff) {
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set_Grad_T(grad_T);
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set_Grad_X(grad_X);
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const doublereal* y = m_thermo->massFractions();
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const doublereal rho = m_thermo->density();
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getSpeciesFluxesExt(m_nsp, DATA_PTR(Vdiff));
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for (int n = 0; n < m_nDim; n++) {
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for (int k = 0; k < m_nsp; k++) {
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if (y[k] > 1.0E-200) {
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Vdiff[n * m_nsp + k] *= 1.0 / (rho * y[k]);
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} else {
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Vdiff[n * m_nsp + k] = 0.0;
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}
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}
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}
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}
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//================================================================================================
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// Get the species diffusive velocities wrt to the averaged velocity,
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// given the gradients in mole fraction, temperature and electrostatic potential.
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/*
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* The average velocity can be computed on a mole-weighted
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* or mass-weighted basis, or the diffusion velocities may
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* be specified as relative to a specific species (i.e. a
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* solvent) all according to the velocityBasis input parameter.
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*
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* Units for the returned velocities are m s-1.
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*
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* @param ndim Number of dimensions in the flux expressions
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* @param grad_T Gradient of the temperature
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* (length = ndim)
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* @param ldx Leading dimension of the grad_X array
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* (usually equal to m_nsp but not always)
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* @param grad_X Gradients of the mole fraction
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* Flat vector with the m_nsp in the inner loop.
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* length = ldx * ndim
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* @param ldf Leading dimension of the fluxes array
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* (usually equal to m_nsp but not always)
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* @param grad_Phi Gradients of the electrostatic potential
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* (length = ndim)
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* @param Vdiff Output of the species diffusion velocities
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* Flat vector with the m_nsp in the inner loop.
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* length = ldx * ndim
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*/
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void SimpleTransport::getSpeciesVdiffES(int ndim, const doublereal* grad_T,
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int ldx, const doublereal* grad_X,
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int ldf, const doublereal* grad_Phi,
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doublereal* Vdiff) {
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set_Grad_T(grad_T);
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set_Grad_X(grad_X);
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set_Grad_V(grad_Phi);
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const doublereal* y = m_thermo->massFractions();
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const doublereal rho = m_thermo->density();
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getSpeciesFluxesExt(m_nsp, DATA_PTR(Vdiff));
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for (int n = 0; n < m_nDim; n++) {
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for (int k = 0; k < m_nsp; k++) {
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if (y[k] > 1.0E-200) {
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Vdiff[n * m_nsp + k] *= 1.0 / (rho * y[k]);
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} else {
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Vdiff[n * m_nsp + k] = 0.0;
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}
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}
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}
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}
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//================================================================================================
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// Get the species diffusive mass fluxes wrt to the specified solution averaged velocity,
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// given the gradients in mole fraction and temperature
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@ -673,33 +771,34 @@ namespace Cantera {
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const array_fp& mw = m_thermo->molecularWeights();
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const doublereal* y = m_thermo->massFractions();
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doublereal conc = m_thermo->molarDensity();
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doublereal concTotal = m_thermo->molarDensity();
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// Unroll wrt ndim
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vector_fp sum(m_nDim, 0.0);
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if (doMigration_) {
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double FRT = ElectronCharge / (Boltzmann * m_temp);
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for (n = 0; n < m_nDim; n++) {
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rhoVc[n] = 0.0;
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for (k = 0; k < m_nsp; k++) {
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fluxes[n*ldf + k] = -conc * mw[k] * m_spwork[k] *
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fluxes[n*ldf + k] = - concTotal * mw[k] * m_spwork[k] *
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( m_Grad_X[n*m_nsp + k] + FRT * m_molefracs[k] * m_chargeSpecies[k] * m_Grad_V[n]);
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sum[n] += fluxes[n*ldf + k];
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rhoVc[n] += fluxes[n*ldf + k];
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}
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}
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} else {
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for (n = 0; n < m_nDim; n++) {
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rhoVc[n] = 0.0;
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for (k = 0; k < m_nsp; k++) {
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fluxes[n*ldf + k] = -conc * mw[k] * m_spwork[k] * m_Grad_X[n*m_nsp + k];
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sum[n] += fluxes[n*ldf + k];
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fluxes[n*ldf + k] = - concTotal * mw[k] * m_spwork[k] * m_Grad_X[n*m_nsp + k];
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rhoVc[n] += fluxes[n*ldf + k];
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}
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}
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}
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// add correction flux to enforce sum to zero
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// Add correction flux to enforce sum to zero
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for (n = 0; n < m_nDim; n++) {
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for (k = 0; k < m_nsp; k++) {
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fluxes[n*ldf + k] -= y[k]*sum[n];
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fluxes[n*ldf + k] -= y[k] * rhoVc[n];
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}
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}
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}
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@ -156,6 +156,53 @@ namespace Cantera {
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* The diffusion coefficients, \f$ D_k \f$ , is calculated from a call to the mixture diffusion
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* coefficient routine.
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*
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* <H2> Species Diffusive Fluxes </H2>
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*
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* The diffusive mass flux of species \e k is computed from the following
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* formula
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*
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* Usually the specified solution average velocity is the mass averaged velocity.
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* This is changed in some subclasses, however.
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*
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* \f[
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* j_k = - c^T M_k D_k \nabla X_k - \rho Y_k V_c
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* \f]
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*
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* where V_c is the correction velocity
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*
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* \f[
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* \rho V_c = - \sum_j {c^T M_j D_j \nabla X_j}
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* \f]
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*
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* In the above equation, \f$ D_k \f$ is the mixture diffusivity for species k calculated for the current
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* conditions, which may depend on T, P, and X_k. \f$ C^T \f$ is the total concentration of the phase.
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*
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* When this is electrical migration, the formulas above are enhanced to
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*
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* \f[
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* j_k = - C^T M_k D_k \nabla X_k + F C^T M_k \frac{D_k}{ R T } X_k z_k \nabla V - \rho Y_k V_c
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* \f]
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*
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* where V_c is the correction velocity
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*
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* \f[
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* \rho V_c = - \sum_j {c^T M_j D_j \nabla X_j} + \sum_j F C^T M_j \frac{D_j}{ R T } X_j z_j \nabla V
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* \f]
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*
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*
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* <H2> Species Diffusional Velocities </H2>
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*
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* Species diffusional velocities are calculated from the species diffusional fluxes, within this object,
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* using the following formula for the diffusional velocity of the kth species, \f$ V_k^d \f$
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*
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* \f[
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* j_k = \rho Y_k V_k^d
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* \f]
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*
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*
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* TODO
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* This object has to be made compatible with different types of reference velocities. Right now, elements
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* of the formulas are only compatible with the mass-averaged velocity.
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*
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* @ingroup tranprops
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*
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@ -364,6 +411,69 @@ namespace Cantera {
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*/
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virtual void set_Grad_X(const doublereal * const grad_X);
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//! Get the species diffusive velocities wrt to the averaged velocity,
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//! given the gradients in mole fraction and temperature
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/*!
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* The average velocity can be computed on a mole-weighted
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* or mass-weighted basis, or the diffusion velocities may
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* be specified as relative to a specific species (i.e. a
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* solvent) all according to the velocityBasis input parameter.
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*
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* Units for the returned velocities are m s-1.
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*
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* @param ndim Number of dimensions in the flux expressions
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* @param grad_T Gradient of the temperature
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* (length = ndim)
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* @param ldx Leading dimension of the grad_X array
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* (usually equal to m_nsp but not always)
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* @param grad_X Gradients of the mole fraction
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* Flat vector with the m_nsp in the inner loop.
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* length = ldx * ndim
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* @param ldf Leading dimension of the fluxes array
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* (usually equal to m_nsp but not always)
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* @param Vdiff Output of the diffusive velocities.
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* Flat vector with the m_nsp in the inner loop.
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* length = ldx * ndim
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*/
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virtual void getSpeciesVdiff(int ndim,
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const doublereal* grad_T,
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int ldx,
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const doublereal* grad_X,
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int ldf,
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doublereal* Vdiff);
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//! Get the species diffusive velocities wrt to the averaged velocity,
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//! given the gradients in mole fraction, temperature and electrostatic potential.
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/*!
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* The average velocity can be computed on a mole-weighted
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* or mass-weighted basis, or the diffusion velocities may
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* be specified as relative to a specific species (i.e. a
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* solvent) all according to the velocityBasis input parameter.
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*
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* Units for the returned velocities are m s-1.
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*
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* @param ndim Number of dimensions in the flux expressions
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* @param grad_T Gradient of the temperature
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* (length = ndim)
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* @param ldx Leading dimension of the grad_X array
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* (usually equal to m_nsp but not always)
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* @param grad_X Gradients of the mole fraction
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* Flat vector with the m_nsp in the inner loop.
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* length = ldx * ndim
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* @param ldf Leading dimension of the fluxes array
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* (usually equal to m_nsp but not always)
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* @param grad_Phi Gradients of the electrostatic potential
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* (length = ndim)
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* @param Vdiff Output of the species diffusion velocities
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* Flat vector with the m_nsp in the inner loop.
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* length = ldx * ndim
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*/
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virtual void getSpeciesVdiffES(int ndim, const doublereal* grad_T,
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int ldx, const doublereal* grad_X,
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int ldf, const doublereal* grad_Phi,
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doublereal* Vdiff);
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//! Get the species diffusive mass fluxes wrt to the specified solution averaged velocity,
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//! given the gradients in mole fraction and temperature
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/*!
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@ -723,6 +833,8 @@ namespace Cantera {
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*/
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vector_fp m_spwork;
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vector_fp m_fluxes;
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private:
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@ -755,6 +867,9 @@ namespace Cantera {
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*/
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int m_nDim;
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//! Temporary variable that stores the rho Vc value
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double rhoVc[3];
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private:
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//! Throw an exception if this method is invoked.
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