vcs_inest.cpp

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/**
 * @file vcs_inest.cpp
 *   Implementation methods for obtaining a good initial guess
 */
 
// This file is part of Cantera. See License.txt in the top-level directory or
// at https://cantera.org/license.txt for license and copyright information.
 
#include "cantera/equil/vcs_solve.h"
#include "cantera/equil/vcs_VolPhase.h"
 
#include "cantera/base/clockWC.h"
 
namespace Cantera
{
 
static char pprefix[20] = "   --- vcs_inest: ";
 
void VCS_SOLVE::vcs_inest(double* const aw, double* const sa, double* const sm,
                          double* const ss, double test)
{
    size_t nrxn = m_numRxnTot;
 
    // CALL ROUTINE TO SOLVE MAX(CC*molNum) SUCH THAT AX*molNum = BB AND
    // molNum(I) .GE. 0.0. Note, both of these programs do this.
    vcs_setMolesLinProg();
 
    if (m_debug_print_lvl >= 2) {
        plogf("%s Mole Numbers returned from linear programming (vcs_inest initial guess):\n",
              pprefix);
        plogf("%s     SPECIES          MOLE_NUMBER      -SS_ChemPotential\n", pprefix);
        for (size_t kspec = 0; kspec < m_nsp; ++kspec) {
            plogf("%s     ", pprefix);
            plogf("%-12.12s", m_speciesName[kspec]);
            plogf(" %15.5g  %12.3g\n", m_molNumSpecies_old[kspec], -m_SSfeSpecies[kspec]);
        }
        plogf("%s Element Abundance Agreement returned from linear "
              "programming (vcs_inest initial guess):\n", pprefix);
        plogf("%s     Element           Goal         Actual\n", pprefix);
        for (size_t j = 0; j < m_nelem; j++) {
            if (m_elementActive[j]) {
                double tmp = 0.0;
                for (size_t kspec = 0; kspec < m_nsp; ++kspec) {
                    tmp += m_formulaMatrix(kspec,j) * m_molNumSpecies_old[kspec];
                }
                plogf("%s     ", pprefix);
                plogf("   %-9.9s", m_elementName[j]);
                plogf(" %12.3g %12.3g\n", m_elemAbundancesGoal[j], tmp);
            }
        }
        writelogendl();
    }
 
    // Make sure all species have positive definite mole numbers Set voltages to
    // zero for now, until we figure out what to do
    m_deltaMolNumSpecies.assign(m_deltaMolNumSpecies.size(), 0.0);
    for (size_t kspec = 0; kspec < m_nsp; ++kspec) {
        if (m_speciesUnknownType[kspec] != VCS_SPECIES_TYPE_INTERFACIALVOLTAGE) {
            if (m_molNumSpecies_old[kspec] <= 0.0) {
                // HKM Should eventually include logic here for non SS phases
                if (!m_SSPhase[kspec]) {
                    m_molNumSpecies_old[kspec] = 1.0e-30;
                }
            }
        } else {
            m_molNumSpecies_old[kspec] = 0.0;
        }
    }
 
    // Now find the optimized basis that spans the stoichiometric coefficient
    // matrix
    bool conv;
    vcs_basopt(false, aw, sa, sm, ss, test, &conv);
 
    // CALCULATE TOTAL MOLES, CHEMICAL POTENTIALS OF BASIS
 
    // Calculate TMoles and m_tPhaseMoles_old[]
    vcs_tmoles();
 
    // m_tPhaseMoles_new[] will consist of just the component moles
    for (size_t iph = 0; iph < m_numPhases; iph++) {
        m_tPhaseMoles_new[iph] = TPhInertMoles[iph] + 1.0E-20;
    }
    for (size_t kspec = 0; kspec < m_numComponents; ++kspec) {
        if (m_speciesUnknownType[kspec] == VCS_SPECIES_TYPE_MOLNUM) {
            m_tPhaseMoles_new[m_phaseID[kspec]] += m_molNumSpecies_old[kspec];
        }
    }
    double TMolesMultiphase = 0.0;
    for (size_t iph = 0; iph < m_numPhases; iph++) {
        if (! m_VolPhaseList[iph]->m_singleSpecies) {
            TMolesMultiphase += m_tPhaseMoles_new[iph];
        }
    }
    m_molNumSpecies_new = m_molNumSpecies_old;
    for (size_t kspec = 0; kspec < m_numComponents; ++kspec) {
        if (m_speciesUnknownType[kspec] != VCS_SPECIES_TYPE_MOLNUM) {
            m_molNumSpecies_new[kspec] = 0.0;
        }
    }
    m_feSpecies_new = m_SSfeSpecies;
 
    for (size_t kspec = 0; kspec < m_numComponents; ++kspec) {
        if (m_speciesUnknownType[kspec] == VCS_SPECIES_TYPE_MOLNUM) {
            if (! m_SSPhase[kspec]) {
                size_t iph = m_phaseID[kspec];
                m_feSpecies_new[kspec] += log(m_molNumSpecies_new[kspec] / m_tPhaseMoles_old[iph]);
            }
        } else {
            m_molNumSpecies_new[kspec] = 0.0;
        }
    }
    vcs_deltag(0, true, VCS_STATECALC_NEW);
    if (m_debug_print_lvl >= 2) {
        for (size_t kspec = 0; kspec < m_nsp; ++kspec) {
            plogf("%s", pprefix);
            plogf("%-12.12s", m_speciesName[kspec]);
            if (kspec < m_numComponents) {
                plogf("fe* = %15.5g ff = %15.5g\n", m_feSpecies_new[kspec],
                      m_SSfeSpecies[kspec]);
            } else {
                plogf("fe* = %15.5g ff = %15.5g dg* = %15.5g\n",
                      m_feSpecies_new[kspec], m_SSfeSpecies[kspec], m_deltaGRxn_new[kspec-m_numComponents]);
            }
        }
    }
 
    // ESTIMATE REACTION ADJUSTMENTS
    vector_fp& xtphMax = m_TmpPhase;
    vector_fp& xtphMin = m_TmpPhase2;
    m_deltaPhaseMoles.assign(m_deltaPhaseMoles.size(), 0.0);
    for (size_t iph = 0; iph < m_numPhases; iph++) {
        xtphMax[iph] = log(m_tPhaseMoles_new[iph] * 1.0E32);
        xtphMin[iph] = log(m_tPhaseMoles_new[iph] * 1.0E-32);
    }
    for (size_t irxn = 0; irxn < nrxn; ++irxn) {
        size_t kspec = m_indexRxnToSpecies[irxn];
 
        // For single species phases, we will not estimate the mole numbers. If
        // the phase exists, it stays. If it doesn't exist in the estimate, it
        // doesn't come into existence here.
        if (! m_SSPhase[kspec]) {
            size_t iph = m_phaseID[kspec];
            if (m_deltaGRxn_new[irxn] > xtphMax[iph]) {
                m_deltaGRxn_new[irxn] = 0.8 * xtphMax[iph];
            }
            if (m_deltaGRxn_new[irxn] < xtphMin[iph]) {
                m_deltaGRxn_new[irxn] = 0.8 * xtphMin[iph];
            }
 
            // HKM -> The TMolesMultiphase is a change of mine. It more evenly
            // distributes the initial moles amongst multiple multispecies
            // phases according to the relative values of the standard state
            // free energies. There is no change for problems with one
            // multispecies phase. It cut diamond4.vin iterations down from 62
            // to 14.
            m_deltaMolNumSpecies[kspec] = 0.5 * (m_tPhaseMoles_new[iph] + TMolesMultiphase)
                                          * exp(-m_deltaGRxn_new[irxn]);
 
            for (size_t k = 0; k < m_numComponents; ++k) {
                m_deltaMolNumSpecies[k] += m_stoichCoeffRxnMatrix(k,irxn) * m_deltaMolNumSpecies[kspec];
            }
 
            for (iph = 0; iph < m_numPhases; iph++) {
                m_deltaPhaseMoles[iph] += m_deltaMolNumPhase(iph,irxn) * m_deltaMolNumSpecies[kspec];
            }
        }
    }
    if (m_debug_print_lvl >= 2) {
        for (size_t kspec = 0; kspec < m_nsp; ++kspec) {
            if (m_speciesUnknownType[kspec] != VCS_SPECIES_TYPE_INTERFACIALVOLTAGE) {
                plogf("%sdirection (", pprefix);
                plogf("%-12.12s", m_speciesName[kspec]);
                plogf(") = %g", m_deltaMolNumSpecies[kspec]);
                if (m_SSPhase[kspec]) {
                    if (m_molNumSpecies_old[kspec] > 0.0) {
                        plogf(" (ssPhase exists at w = %g moles)", m_molNumSpecies_old[kspec]);
                    } else {
                        plogf(" (ssPhase doesn't exist -> stability not checked)");
                    }
                }
                writelogendl();
            }
        }
    }
 
    // KEEP COMPONENT SPECIES POSITIVE
    double par = 0.5;
    for (size_t kspec = 0; kspec < m_numComponents; ++kspec) {
        if (m_speciesUnknownType[kspec] != VCS_SPECIES_TYPE_INTERFACIALVOLTAGE &&
            par < -m_deltaMolNumSpecies[kspec] / m_molNumSpecies_new[kspec]) {
            par = -m_deltaMolNumSpecies[kspec] / m_molNumSpecies_new[kspec];
        }
    }
    par = 1. / par;
    if (par <= 1.0 && par > 0.0) {
        par *= 0.8;
    } else {
        par = 1.0;
    }
 
    // CALCULATE NEW MOLE NUMBERS
    size_t lt = 0;
    size_t ikl = 0;
    double s1 = 0.0;
    while (true) {
        for (size_t kspec = 0; kspec < m_numComponents; ++kspec) {
            if (m_speciesUnknownType[kspec] != VCS_SPECIES_TYPE_INTERFACIALVOLTAGE) {
                m_molNumSpecies_old[kspec] = m_molNumSpecies_new[kspec] + par * m_deltaMolNumSpecies[kspec];
            } else {
                m_deltaMolNumSpecies[kspec] = 0.0;
            }
        }
        for (size_t kspec = m_numComponents; kspec < m_nsp; ++kspec) {
            if (m_speciesUnknownType[kspec] != VCS_SPECIES_TYPE_INTERFACIALVOLTAGE &&
                m_deltaMolNumSpecies[kspec] != 0.0) {
                m_molNumSpecies_old[kspec] = m_deltaMolNumSpecies[kspec] * par;
            }
        }
 
        // We have a new w[] estimate, go get the TMoles and m_tPhaseMoles_old[]
        // values
        vcs_tmoles();
        if (lt > 0) {
            break;
        }
 
        // CONVERGENCE FORCING SECTION
        vcs_setFlagsVolPhases(false, VCS_STATECALC_OLD);
        vcs_dfe(VCS_STATECALC_OLD, 0, 0, m_nsp);
        double s = 0.0;
        for (size_t kspec = 0; kspec < m_nsp; ++kspec) {
            s += m_deltaMolNumSpecies[kspec] * m_feSpecies_old[kspec];
        }
        if (s == 0.0) {
            break;
        }
        if (s < 0.0 && ikl == 0) {
            break;
        }
 
        // TRY HALF STEP SIZE
        if (ikl == 0) {
            s1 = s;
            par *= 0.5;
            ikl = 1;
            continue;
        }
 
        // FIT PARABOLA THROUGH HALF AND FULL STEPS
        double xl = (1.0 - s / (s1 - s)) * 0.5;
        if (xl < 0.0) {
            // POOR DIRECTION, REDUCE STEP SIZE TO 0.2
            par *= 0.2;
        } else {
            if (xl > 1.0) {
                // TOO BIG A STEP, TAKE ORIGINAL FULL STEP
                par *= 2.0;
            } else {
                // ACCEPT RESULTS OF FORCER
                par = par * 2.0 * xl;
            }
        }
        lt = 1;
    }
 
    if (m_debug_print_lvl >= 2) {
        plogf("%s     Final Mole Numbers produced by inest:\n",
              pprefix);
        plogf("%s     SPECIES      MOLE_NUMBER\n", pprefix);
        for (size_t kspec = 0; kspec < m_nsp; ++kspec) {
            plogf("%s     %-12.12s %g\n",
                pprefix, m_speciesName[kspec], m_molNumSpecies_old[kspec]);
        }
    }
}
 
int VCS_SOLVE::vcs_inest_TP()
{
    int retn = 0;
    clockWC tickTock;
    if (m_doEstimateEquil > 0) {
        // Calculate the elemental abundances
        vcs_elab();
        if (vcs_elabcheck(0)) {
            if (m_debug_print_lvl >= 2) {
                plogf("%s Initial guess passed element abundances on input\n", pprefix);
                plogf("%s m_doEstimateEquil = 1 so will use the input mole "
                      "numbers as estimates\n", pprefix);
            }
            return retn;
        } else if (m_debug_print_lvl >= 2) {
            plogf("%s Initial guess failed element abundances on input\n", pprefix);
            plogf("%s m_doEstimateEquil = 1 so will discard input "
                  "mole numbers and find our own estimate\n", pprefix);
        }
    }
 
    // temporary space for usage in this routine and in subroutines
    vector_fp sm(m_nelem*m_nelem, 0.0);
    vector_fp ss(m_nelem, 0.0);
    vector_fp sa(m_nelem, 0.0);
    vector_fp aw(m_nsp + m_nelem, 0.0);
 
    // Go get the estimate of the solution
    if (m_debug_print_lvl >= 2) {
        plogf("%sGo find an initial estimate for the equilibrium problem\n",
              pprefix);
    }
    double test = -1.0E20;
    vcs_inest(&aw[0], &sa[0], &sm[0], &ss[0], test);
 
    // Calculate the elemental abundances
    vcs_elab();
 
    // If we still fail to achieve the correct elemental abundances, try to fix
    // the problem again by calling the main elemental abundances fixer routine,
    // used in the main program. This attempts to tweak the mole numbers of the
    // component species to satisfy the element abundance constraints.
    //
    // Note: We won't do this unless we have to since it involves inverting a
    // matrix.
    bool rangeCheck = vcs_elabcheck(1);
    if (!vcs_elabcheck(0)) {
        if (m_debug_print_lvl >= 2) {
            plogf("%sInitial guess failed element abundances\n", pprefix);
            plogf("%sCall vcs_elcorr to attempt fix\n", pprefix);
        }
        vcs_elcorr(&sm[0], &aw[0]);
        rangeCheck = vcs_elabcheck(1);
        if (!vcs_elabcheck(0)) {
            plogf("%sInitial guess still fails element abundance equations\n",
                  pprefix);
            plogf("%s - Inability to ever satisfy element abundance "
                  "constraints is probable\n", pprefix);
            retn = -1;
        } else {
            if (m_debug_print_lvl >= 2) {
                if (rangeCheck) {
                    plogf("%sInitial guess now satisfies element abundances\n", pprefix);
                } else {
                    plogf("%sElement Abundances RANGE ERROR\n", pprefix);
                    plogf("%s - Initial guess satisfies NC=%d element abundances, "
                          "BUT not NE=%d element abundances\n", pprefix,
                          m_numComponents, m_nelem);
                }
            }
        }
    } else {
        if (m_debug_print_lvl >= 2) {
            if (rangeCheck) {
                plogf("%sInitial guess satisfies element abundances\n", pprefix);
            } else {
                plogf("%sElement Abundances RANGE ERROR\n", pprefix);
                plogf("%s - Initial guess satisfies NC=%d element abundances, "
                      "BUT not NE=%d element abundances\n", pprefix,
                      m_numComponents, m_nelem);
            }
        }
    }
 
    if (m_debug_print_lvl >= 2) {
        plogf("%sTotal Dimensionless Gibbs Free Energy = %15.7E\n", pprefix,
              vcs_Total_Gibbs(&m_molNumSpecies_old[0], &m_feSpecies_new[0],
                              &m_tPhaseMoles_old[0]));
    }
 
    // Record time
    m_VCount->T_Time_inest += tickTock.secondsWC();
    m_VCount->T_Calls_Inest++;
    return retn;
}
 
}