Swan2012AcinarUnit.cpp

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*/

#include "Swan2012AcinarUnit.hpp"
#include <cmath>
#include <iostream>


Swan2012AcinarUnit::Swan2012AcinarUnit() : mQ(0.0),
                                           mLambda(1.26),
                                           mDt(-1),
                                           mPaw(0.0),
                                           mPawOld(0.0),
                                           mPpl(0.0),
                                           mPplOld(0.0),
                                           mRaw(0.0),
                                           mA(0.433),
                                           mB(0.611),
                                           mXi(2.5),
                                           mV0(1.0)
{

}


Swan2012AcinarUnit::~Swan2012AcinarUnit()
{
}

void Swan2012AcinarUnit::SolveAndUpdateState(double tStart, double tEnd)
{
    //Update stretch component
    double dPe = (mPaw - mPawOld) - (mPpl - mPplOld);
    double dLambda_dPe = 1.0/CalculateDerivativeStaticRecoilPressureByStrain();

    mLambda = mLambda + dLambda_dPe*dPe;

    //Update flow
    double c_a = CalculateAcinarTissueCompliance(); //Need to incorporate Ca(CW) too

    double dt = tEnd - tStart;
    double nu = (mPaw - mPawOld)/dt;
    double beta = (mPpl - mPplOld)/dt;

    mQ = c_a*(nu - beta) + (mQ - c_a*(nu - beta))*std::exp(-dt/(mRaw*c_a));
}

void Swan2012AcinarUnit::SetFlow(double flow)
{
    mQ = flow;
}

double Swan2012AcinarUnit::GetFlow()
{
    return mQ;
}

void Swan2012AcinarUnit::SetAirwayPressure(double pressure)
{
    mPawOld = mPaw;
    mPaw = pressure;
}

void Swan2012AcinarUnit::SetPleuralPressure(double pressure)
{
    mPplOld = mPpl;
    mPpl = pressure;
}

void Swan2012AcinarUnit::SetTerminalBronchioleResistance(double raw)
{
    mRaw = raw;
}

double Swan2012AcinarUnit::GetStretchRatio()
{
    return mLambda;
}

void Swan2012AcinarUnit::SetStretchRatio(double lambda)
{
    mLambda = lambda;
}


double Swan2012AcinarUnit::GetVolume()
{
    return mLambda*mLambda*mLambda*mV0;
}

void Swan2012AcinarUnit::SetUndeformedVolume(double v0)
{
    mV0 = v0;
}

double Swan2012AcinarUnit::CalculateDerivativeVolumeByStrain()
{
    return 3*mLambda*mLambda*mV0;
}

double Swan2012AcinarUnit::CalculateDerivativeStaticRecoilPressureByStrain()
{
    double gamma = CalculateGamma();
    return ((3.0*mXi/2.0)*(3*mA + mB)*(3*mA + mB)*(mLambda*mLambda - 1)*(mLambda*mLambda - 1)*std::exp(gamma) +
            (mXi/2.0)*(3*mA + mB)*(mLambda*mLambda + 1)*std::exp(gamma)/(mLambda*mLambda));
}

double Swan2012AcinarUnit::CalculateGamma()
{
    return (3.0/4.0)*(3*mA + mB)*(mLambda*mLambda - 1)*(mLambda*mLambda - 1);
}

double Swan2012AcinarUnit::CalculateAcinarTissueCompliance()
{
    return CalculateDerivativeVolumeByStrain()/CalculateDerivativeStaticRecoilPressureByStrain();
}