cantera/src/transport/MultiTransport.cpp

704 lines
22 KiB
C++

/**
* @file MultiTransport.cpp
* Implementation file for class MultiTransport
*/
/*
* Copyright 2001 California Institute of Technology
* See file License.txt for licensing information
*/
#include "cantera/transport/MultiTransport.h"
#include "cantera/thermo/IdealGasPhase.h"
#include "cantera/base/stringUtils.h"
using namespace std;
namespace Cantera
{
///////////////////// helper functions /////////////////////////
/**
* The Parker temperature correction to the rotational collision number.
*
* @param tr Reduced temperature \f$ \epsilon/kT \f$
* @param sqtr square root of tr.
*/
doublereal Frot(doublereal tr, doublereal sqtr)
{
const doublereal c1 = 0.5*sqrt(Pi)*Pi;
const doublereal c2 = 0.25*Pi*Pi + 2.0;
const doublereal c3 = sqrt(Pi)*Pi;
return 1.0 + c1*sqtr + c2*tr + c3*sqtr*tr;
}
//////////////////// class MultiTransport methods //////////////
MultiTransport::MultiTransport(thermo_t* thermo)
: GasTransport(thermo)
{
}
void MultiTransport::init(ThermoPhase* thermo, int mode, int log_level)
{
GasTransport::init(thermo, mode, log_level);
// the L matrix
m_Lmatrix.resize(3*m_nsp, 3*m_nsp);
m_a.resize(3*m_nsp, 1.0);
m_b.resize(3*m_nsp, 0.0);
m_aa.resize(m_nsp, m_nsp, 0.0);
m_molefracs_last.resize(m_nsp, -1.0);
m_frot_298.resize(m_nsp);
m_rotrelax.resize(m_nsp);
m_cinternal.resize(m_nsp);
m_om22.resize(m_nsp, m_nsp);
m_astar.resize(m_nsp, m_nsp);
m_bstar.resize(m_nsp, m_nsp);
m_cstar.resize(m_nsp, m_nsp);
// set flags all false
m_abc_ok = false;
m_l0000_ok = false;
m_lmatrix_soln_ok = false;
m_thermal_tlast = 0.0;
// some work space
m_spwork1.resize(m_nsp);
m_spwork2.resize(m_nsp);
m_spwork3.resize(m_nsp);
// precompute and store log(epsilon_ij/k_B)
m_log_eps_k.resize(m_nsp, m_nsp);
for (size_t i = 0; i < m_nsp; i++) {
for (size_t j = i; j < m_nsp; j++) {
m_log_eps_k(i,j) = log(m_epsilon(i,j)/Boltzmann);
m_log_eps_k(j,i) = m_log_eps_k(i,j);
}
}
// precompute and store constant parts of the Parker rotational
// collision number temperature correction
const doublereal sq298 = sqrt(298.0);
const doublereal kb298 = Boltzmann * 298.0;
m_sqrt_eps_k.resize(m_nsp);
for (size_t k = 0; k < m_nsp; k++) {
m_sqrt_eps_k[k] = sqrt(m_eps[k]/Boltzmann);
m_frot_298[k] = Frot(m_eps[k]/kb298, m_sqrt_eps_k[k]/sq298);
}
}
doublereal MultiTransport::thermalConductivity()
{
solveLMatrixEquation();
doublereal sum = 0.0;
for (size_t k = 0; k < 2*m_nsp; k++) {
sum += m_b[k + m_nsp] * m_a[k + m_nsp];
}
return -4.0*sum;
}
void MultiTransport::getThermalDiffCoeffs(doublereal* const dt)
{
solveLMatrixEquation();
const doublereal c = 1.6/GasConstant;
for (size_t k = 0; k < m_nsp; k++) {
dt[k] = c * m_mw[k] * m_molefracs[k] * m_a[k];
}
}
void MultiTransport::solveLMatrixEquation()
{
// if T has changed, update the temperature-dependent properties.
updateThermal_T();
update_C();
if (m_lmatrix_soln_ok) {
return;
}
// Copy the mole fractions twice into the last two blocks of the right-hand-
// side vector m_b. The first block of m_b was set to zero when it was
// created, and is not modified so doesn't need to be reset to zero.
for (size_t k = 0; k < m_nsp; k++) {
m_b[k] = 0.0;
m_b[k + m_nsp] = m_molefracs[k];
m_b[k + 2*m_nsp] = m_molefracs[k];
}
// Set the right-hand side vector to zero in the 3rd block for all species
// with no internal energy modes. The corresponding third-block rows and
// columns will be set to zero, except on the diagonal of L01,01, where they
// are set to 1.0. This has the effect of eliminating these equations from
// the system, since the equation becomes: m_a[2*m_nsp + k] = 0.0.
// Note that this differs from the Chemkin procedure, where all *monatomic*
// species are excluded. Since monatomic radicals can have non-zero internal
// heat capacities due to electronic excitation, they should be retained.
for (size_t k = 0; k < m_nsp; k++) {
if (!hasInternalModes(k)) {
m_b[2*m_nsp + k] = 0.0;
}
}
// evaluate the submatrices of the L matrix
m_Lmatrix.resize(3*m_nsp, 3*m_nsp, 0.0);
//! Evaluate the upper-left block of the L matrix.
eval_L0000(m_molefracs.data());
eval_L0010(m_molefracs.data());
eval_L0001();
eval_L1000();
eval_L1010(m_molefracs.data());
eval_L1001(m_molefracs.data());
eval_L0100();
eval_L0110();
eval_L0101(m_molefracs.data());
// Solve it using GMRES or LU decomposition. The last solution in m_a should
// provide a good starting guess, so convergence should be fast.
m_a = m_b;
try {
solve(m_Lmatrix, m_a.data());
} catch (CanteraError& err) {
err.save();
throw CanteraError("MultiTransport::solveLMatrixEquation",
"error in solving L matrix.");
}
m_lmatrix_soln_ok = true;
m_molefracs_last = m_molefracs;
// L matrix is overwritten with LU decomposition
m_l0000_ok = false;
}
void MultiTransport::getSpeciesFluxes(size_t ndim, const doublereal* const grad_T,
size_t ldx, const doublereal* const grad_X,
size_t ldf, doublereal* const fluxes)
{
// update the binary diffusion coefficients if necessary
update_T();
updateDiff_T();
// If any component of grad_T is non-zero, then get the
// thermal diffusion coefficients
bool addThermalDiffusion = false;
for (size_t i = 0; i < ndim; i++) {
if (grad_T[i] != 0.0) {
addThermalDiffusion = true;
}
}
if (addThermalDiffusion) {
getThermalDiffCoeffs(m_spwork.data());
}
const doublereal* y = m_thermo->massFractions();
doublereal rho = m_thermo->density();
for (size_t i = 0; i < m_nsp; i++) {
double sum = 0.0;
for (size_t j = 0; j < m_nsp; j++) {
m_aa(i,j) = m_molefracs[j]*m_molefracs[i]/m_bdiff(i,j);
sum += m_aa(i,j);
}
m_aa(i,i) -= sum;
}
// enforce the condition \sum Y_k V_k = 0. This is done by replacing
// the flux equation with the largest gradx component in the first
// coordinate direction with the flux balance condition.
size_t jmax = 0;
doublereal gradmax = -1.0;
for (size_t j = 0; j < m_nsp; j++) {
if (fabs(grad_X[j]) > gradmax) {
gradmax = fabs(grad_X[j]);
jmax = j;
}
}
// set the matrix elements in this row to the mass fractions,
// and set the entry in gradx to zero
for (size_t j = 0; j < m_nsp; j++) {
m_aa(jmax,j) = y[j];
}
vector_fp gsave(ndim), grx(ldx*m_nsp);
for (size_t n = 0; n < ldx*ndim; n++) {
grx[n] = grad_X[n];
}
// copy grad_X to fluxes
const doublereal* gx;
for (size_t n = 0; n < ndim; n++) {
gx = grad_X + ldx*n;
copy(gx, gx + m_nsp, fluxes + ldf*n);
fluxes[jmax + n*ldf] = 0.0;
}
// use LAPACK to solve the equations
int info = m_aa.factor();
if (info) {
throw CanteraError("MultiTransport::getSpeciesFluxes",
"Error factorizing matrix.");
}
info = m_aa.solve(fluxes, ndim, ldf);
if (info) {
throw CanteraError("MultiTransport::getSpeciesFluxes",
"Error solving linear system.");
}
size_t offset;
doublereal pp = pressure_ig();
// multiply diffusion velocities by rho * V to create mass fluxes, and
// restore the gradx elements that were modified
for (size_t n = 0; n < ndim; n++) {
offset = n*ldf;
for (size_t i = 0; i < m_nsp; i++) {
fluxes[i + offset] *= rho * y[i] / pp;
}
}
// thermal diffusion
if (addThermalDiffusion) {
for (size_t n = 0; n < ndim; n++) {
offset = n*ldf;
doublereal grad_logt = grad_T[n]/m_temp;
for (size_t i = 0; i < m_nsp; i++) {
fluxes[i + offset] -= m_spwork[i]*grad_logt;
}
}
}
}
void MultiTransport::getMassFluxes(const doublereal* state1, const doublereal* state2, doublereal delta,
doublereal* fluxes)
{
double* x1 = m_spwork1.data();
double* x2 = m_spwork2.data();
double* x3 = m_spwork3.data();
size_t n, nsp = m_thermo->nSpecies();
m_thermo->restoreState(nsp+2, state1);
double p1 = m_thermo->pressure();
double t1 = state1[0];
m_thermo->getMoleFractions(x1);
m_thermo->restoreState(nsp+2, state2);
double p2 = m_thermo->pressure();
double t2 = state2[0];
m_thermo->getMoleFractions(x2);
double p = 0.5*(p1 + p2);
double t = 0.5*(state1[0] + state2[0]);
for (n = 0; n < nsp; n++) {
x3[n] = 0.5*(x1[n] + x2[n]);
}
m_thermo->setState_TPX(t, p, x3);
m_thermo->getMoleFractions(m_molefracs.data());
// update the binary diffusion coefficients if necessary
update_T();
updateDiff_T();
// If there is a temperature gradient, then get the
// thermal diffusion coefficients
bool addThermalDiffusion = false;
if (state1[0] != state2[0]) {
addThermalDiffusion = true;
getThermalDiffCoeffs(m_spwork.data());
}
const doublereal* y = m_thermo->massFractions();
doublereal rho = m_thermo->density();
for (size_t i = 0; i < m_nsp; i++) {
doublereal sum = 0.0;
for (size_t j = 0; j < m_nsp; j++) {
m_aa(i,j) = m_molefracs[j]*m_molefracs[i]/m_bdiff(i,j);
sum += m_aa(i,j);
}
m_aa(i,i) -= sum;
}
// enforce the condition \sum Y_k V_k = 0. This is done by replacing the
// flux equation with the largest gradx component with the flux balance
// condition.
size_t jmax = 0;
doublereal gradmax = -1.0;
for (size_t j = 0; j < m_nsp; j++) {
if (fabs(x2[j] - x1[j]) > gradmax) {
gradmax = fabs(x1[j] - x2[j]);
jmax = j;
}
}
// set the matrix elements in this row to the mass fractions,
// and set the entry in gradx to zero
for (size_t j = 0; j < m_nsp; j++) {
m_aa(jmax,j) = y[j];
fluxes[j] = x2[j] - x1[j];
}
fluxes[jmax] = 0.0;
// Solve the equations
int info = m_aa.factor();
if (info) {
throw CanteraError("MultiTransport::getMassFluxes",
"Error in factorization. Info = {}", info);
}
info = m_aa.solve(fluxes);
if (info) {
throw CanteraError("MultiTransport::getMassFluxes",
"Error in linear solve. Info = {}", info);
}
doublereal pp = pressure_ig();
// multiply diffusion velocities by rho * Y_k to create
// mass fluxes, and divide by pressure
for (size_t i = 0; i < m_nsp; i++) {
fluxes[i] *= rho * y[i] / pp;
}
// thermal diffusion
if (addThermalDiffusion) {
doublereal grad_logt = (t2 - t1)/m_temp;
for (size_t i = 0; i < m_nsp; i++) {
fluxes[i] -= m_spwork[i]*grad_logt;
}
}
}
void MultiTransport::getMolarFluxes(const doublereal* const state1,
const doublereal* const state2,
const doublereal delta,
doublereal* const fluxes)
{
getMassFluxes(state1, state2, delta, fluxes);
for (size_t k = 0; k < m_thermo->nSpecies(); k++) {
fluxes[k] /= m_mw[k];
}
}
void MultiTransport::getMultiDiffCoeffs(const size_t ld, doublereal* const d)
{
doublereal p = pressure_ig();
// update the mole fractions
update_C();
// update the binary diffusion coefficients
update_T();
updateThermal_T();
// evaluate L0000 if the temperature or concentrations have
// changed since it was last evaluated.
if (!m_l0000_ok) {
eval_L0000(m_molefracs.data());
}
// invert L00,00
int ierr = invert(m_Lmatrix, m_nsp);
if (ierr != 0) {
throw CanteraError("MultiTransport::getMultiDiffCoeffs",
"invert returned ierr = {}", ierr);
}
m_l0000_ok = false; // matrix is overwritten by inverse
m_lmatrix_soln_ok = false;
doublereal prefactor = 16.0 * m_temp
* m_thermo->meanMolecularWeight()/(25.0 * p);
doublereal c;
for (size_t i = 0; i < m_nsp; i++) {
for (size_t j = 0; j < m_nsp; j++) {
c = prefactor/m_mw[j];
d[ld*j + i] = c*m_molefracs[i]*
(m_Lmatrix(i,j) - m_Lmatrix(i,i));
}
}
}
void MultiTransport::update_T()
{
if (m_temp == m_thermo->temperature()) {
return;
}
GasTransport::update_T();
// temperature has changed, so polynomial fits will need to be
// redone, and the L matrix reevaluated.
m_abc_ok = false;
m_lmatrix_soln_ok = false;
m_l0000_ok = false;
}
void MultiTransport::update_C()
{
// Update the local mole fraction array
m_thermo->getMoleFractions(m_molefracs.data());
for (size_t k = 0; k < m_nsp; k++) {
// add an offset to avoid a pure species condition
m_molefracs[k] = std::max(Tiny, m_molefracs[k]);
if (m_molefracs[k] != m_molefracs_last[k]) {
// If any mole fractions have changed, signal that concentration-
// dependent quantities will need to be recomputed before use.
m_l0000_ok = false;
m_lmatrix_soln_ok = false;
}
}
}
void MultiTransport::updateThermal_T()
{
if (m_thermal_tlast == m_thermo->temperature()) {
return;
}
// we need species viscosities and binary diffusion coefficients
updateSpeciesViscosities();
updateDiff_T();
// evaluate polynomial fits for A*, B*, C*
doublereal z;
int ipoly;
for (size_t i = 0; i < m_nsp; i++) {
for (size_t j = i; j < m_nsp; j++) {
z = m_logt - m_log_eps_k(i,j);
ipoly = m_poly[i][j];
if (m_mode == CK_Mode) {
m_om22(i,j) = poly6(z, m_omega22_poly[ipoly].data());
m_astar(i,j) = poly6(z, m_astar_poly[ipoly].data());
m_bstar(i,j) = poly6(z, m_bstar_poly[ipoly].data());
m_cstar(i,j) = poly6(z, m_cstar_poly[ipoly].data());
} else {
m_om22(i,j) = poly8(z, m_omega22_poly[ipoly].data());
m_astar(i,j) = poly8(z, m_astar_poly[ipoly].data());
m_bstar(i,j) = poly8(z, m_bstar_poly[ipoly].data());
m_cstar(i,j) = poly8(z, m_cstar_poly[ipoly].data());
}
m_om22(j,i) = m_om22(i,j);
m_astar(j,i) = m_astar(i,j);
m_bstar(j,i) = m_bstar(i,j);
m_cstar(j,i) = m_cstar(i,j);
}
}
m_abc_ok = true;
// evaluate the temperature-dependent rotational relaxation rate
doublereal tr, sqtr;
for (size_t k = 0; k < m_nsp; k++) {
tr = m_eps[k]/ m_kbt;
sqtr = m_sqrt_eps_k[k] / m_sqrt_t;
m_rotrelax[k] = std::max(1.0,m_zrot[k]) * m_frot_298[k]/Frot(tr, sqtr);
}
doublereal d;
doublereal c = 1.2*GasConstant*m_temp;
for (size_t k = 0; k < m_nsp; k++) {
d = c * m_visc[k] * m_astar(k,k)/m_mw[k];
m_bdiff(k,k) = d;
}
// Calculate the internal heat capacities by subtracting off the translational contributions
/*
* HKM Exploratory comment:
* The translational component is 1.5
* The rotational component is 1.0 for a linear molecule and 1.5 for a nonlinear molecule
* and zero for a monatomic.
* Chemkin has traditionally subtracted 1.5 here (SAND86-8246).
* The original Dixon-Lewis paper subtracted 1.5 here.
*/
vector_fp cp(m_thermo->nSpecies());
m_thermo->getCp_R_ref(&cp[0]);
for (size_t k = 0; k < m_nsp; k++) {
m_cinternal[k] = cp[k] - 2.5;
}
m_thermal_tlast = m_thermo->temperature();
}
//! Constant to compare dimensionless heat capacities against zero
static const doublereal Min_C_Internal = 0.001;
bool MultiTransport::hasInternalModes(size_t j)
{
return (m_cinternal[j] > Min_C_Internal);
}
void MultiTransport::eval_L0000(const doublereal* const x)
{
doublereal prefactor = 16.0*m_temp/25.0;
doublereal sum;
for (size_t i = 0; i < m_nsp; i++) {
// subtract-off the k=i term to account for the first delta
// function in Eq. (12.121)
sum = -x[i]/m_bdiff(i,i);
for (size_t k = 0; k < m_nsp; k++) {
sum += x[k]/m_bdiff(i,k);
}
sum /= m_mw[i];
for (size_t j = 0; j != m_nsp; ++j) {
m_Lmatrix(i,j) = prefactor * x[j]
* (m_mw[j] * sum + x[i]/m_bdiff(i,j));
}
// diagonal term is zero
m_Lmatrix(i,i) = 0.0;
}
}
void MultiTransport::eval_L0010(const doublereal* const x)
{
doublereal prefactor = 1.6*m_temp;
doublereal sum, wj, xj;
for (size_t j = 0; j < m_nsp; j++) {
xj = x[j];
wj = m_mw[j];
sum = 0.0;
for (size_t i = 0; i < m_nsp; i++) {
m_Lmatrix(i,j + m_nsp) = - prefactor * x[i] * xj * m_mw[i] *
(1.2 * m_cstar(j,i) - 1.0) /
((wj + m_mw[i]) * m_bdiff(j,i));
// the next term is independent of "j";
// need to do it for the "j,j" term
sum -= m_Lmatrix(i,j+m_nsp);
}
m_Lmatrix(j,j+m_nsp) += sum;
}
}
void MultiTransport::eval_L1000()
{
for (size_t j = 0; j < m_nsp; j++) {
for (size_t i = 0; i < m_nsp; i++) {
m_Lmatrix(i+m_nsp,j) = m_Lmatrix(j,i+m_nsp);
}
}
}
void MultiTransport::eval_L1010(const doublereal* x)
{
const doublereal fiveover3pi = 5.0/(3.0*Pi);
doublereal prefactor = (16.0*m_temp)/25.0;
doublereal constant1, wjsq, constant2, constant3, constant4,
fourmj, threemjsq, sum, sumwij;;
doublereal term1, term2;
for (size_t j = 0; j < m_nsp; j++) {
// get constant terms that depend on just species "j"
constant1 = prefactor*x[j];
wjsq = m_mw[j]*m_mw[j];
constant2 = 13.75*wjsq;
constant3 = m_crot[j]/m_rotrelax[j];
constant4 = 7.5*wjsq;
fourmj = 4.0*m_mw[j];
threemjsq = 3.0*m_mw[j]*m_mw[j];
sum = 0.0;
for (size_t i = 0; i < m_nsp; i++) {
sumwij = m_mw[i] + m_mw[j];
term1 = m_bdiff(i,j) * sumwij*sumwij;
term2 = fourmj*m_astar(i,j)*(1.0 + fiveover3pi*
(constant3 +
(m_crot[i]/m_rotrelax[i]))); // see Eq. (12.125)
m_Lmatrix(i+m_nsp,j+m_nsp) = constant1*x[i]*m_mw[i] /(m_mw[j]*term1) *
(constant2 - threemjsq*m_bstar(i,j)
- term2*m_mw[j]);
sum += x[i] /(term1) *
(constant4 + m_mw[i]*m_mw[i]*
(6.25 - 3.0*m_bstar(i,j)) + term2*m_mw[i]);
}
m_Lmatrix(j+m_nsp,j+m_nsp) -= sum*constant1;
}
}
void MultiTransport::eval_L1001(const doublereal* x)
{
doublereal prefactor = 32.00*m_temp/(5.00*Pi);
doublereal constant, sum;
size_t n2 = 2*m_nsp;
int npoly = 0;
for (size_t j = 0; j < m_nsp; j++) {
// collect terms that depend only on "j"
if (hasInternalModes(j)) {
constant = prefactor*m_mw[j]*x[j]*m_crot[j]/(m_cinternal[j]*m_rotrelax[j]);
sum = 0.0;
for (size_t i = 0; i < m_nsp; i++) {
// see Eq. (12.127)
m_Lmatrix(i+m_nsp,j+n2) = constant * m_astar(j,i) * x[i] /
((m_mw[j] + m_mw[i]) * m_bdiff(j,i));
sum += m_Lmatrix(i+m_nsp,j+n2);
}
npoly++;
m_Lmatrix(j+m_nsp,j+n2) += sum;
} else {
for (size_t i = 0; i < m_nsp; i++) {
m_Lmatrix(i+m_nsp,j+n2) = 0.0;
}
}
}
}
void MultiTransport::eval_L0001()
{
size_t n2 = 2*m_nsp;
for (size_t j = 0; j < m_nsp; j++) {
for (size_t i = 0; i < m_nsp; i++) {
m_Lmatrix(i,j+n2) = 0.0;
}
}
}
void MultiTransport::eval_L0100()
{
size_t n2 = 2*m_nsp;
for (size_t j = 0; j < m_nsp; j++) {
for (size_t i = 0; i < m_nsp; i++) {
m_Lmatrix(i+n2,j) = 0.0; // see Eq. (12.123)
}
}
}
void MultiTransport::eval_L0110()
{
size_t n2 = 2*m_nsp;
for (size_t j = 0; j < m_nsp; j++) {
for (size_t i = 0; i < m_nsp; i++) {
m_Lmatrix(i+n2,j+m_nsp) = m_Lmatrix(j+m_nsp,i+n2); // see Eq. (12.123)
}
}
}
void MultiTransport::eval_L0101(const doublereal* x)
{
const doublereal fivepi = 5.00*Pi;
const doublereal eightoverpi = 8.0 / Pi;
doublereal prefactor = 4.00*m_temp;
size_t n2 = 2*m_nsp;
doublereal constant1, constant2, diff_int, sum;
for (size_t i = 0; i < m_nsp; i++) {
if (hasInternalModes(i)) {
// collect terms that depend only on "i"
constant1 = prefactor*x[i]/m_cinternal[i];
constant2 = 12.00*m_mw[i]*m_crot[i] /
(fivepi*m_cinternal[i]*m_rotrelax[i]);
sum = 0.0;
for (size_t k = 0; k < m_nsp; k++) {
// see Eq. (12.131)
diff_int = m_bdiff(i,k);
m_Lmatrix(k+n2,i+n2) = 0.0;
sum += x[k]/diff_int;
if (k != i) sum += x[k]*m_astar(i,k)*constant2 /
(m_mw[k]*diff_int);
}
// see Eq. (12.130)
m_Lmatrix(i+n2,i+n2) =
- eightoverpi*m_mw[i]*x[i]*x[i]*m_crot[i] /
(m_cinternal[i]*m_cinternal[i]*GasConstant*m_visc[i]*m_rotrelax[i])
- constant1*sum;
} else {
for (size_t k = 0; k < m_nsp; k++) {
m_Lmatrix(i+n2,i+n2) = 1.0;
}
}
}
}
}