HertzianViscoelasticNormalSpecies.cc

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#include "HertzianViscoelasticNormalSpecies.h"
#include "Interactions/BaseInteraction.h"
#include<cmath>
#include <Interactions/NormalForceInteractions/HertzianViscoelasticInteraction.h>
#include <Logger.h>

class BaseParticle;
class BaseInteractable;

HertzianViscoelasticNormalSpecies::HertzianViscoelasticNormalSpecies()
{
    elasticModulus_ = 0;
    dissipation_ = 0;
#ifdef DEBUG_CONSTRUCTOR
    std::cout<<"HertzianViscoelasticNormalSpecies::HertzianViscoelasticNormalSpecies() finished"<<std::endl;
#endif
}

HertzianViscoelasticNormalSpecies::HertzianViscoelasticNormalSpecies(const HertzianViscoelasticNormalSpecies &p)
{
    elasticModulus_ = p.elasticModulus_;
    dissipation_ = p.dissipation_;
#ifdef DEBUG_CONSTRUCTOR
    std::cout<<"HertzianViscoelasticNormalSpecies::HertzianViscoelasticNormalSpecies(const HertzianViscoelasticNormalSpecies &p) finished"<<std::endl;
#endif
}

HertzianViscoelasticNormalSpecies::~HertzianViscoelasticNormalSpecies()
{
#ifdef DEBUG_DESTRUCTOR
    std::cout<<"HertzianViscoelasticNormalSpecies::~HertzianViscoelasticNormalSpecies() finished"<<std::endl;
#endif
}

void HertzianViscoelasticNormalSpecies::write(std::ostream& os) const
        {
    os << " stiffness " << elasticModulus_
            << " dissipation " << dissipation_;
}

void HertzianViscoelasticNormalSpecies::read(std::istream& is)
{
    std::string dummy;
    is >> dummy >> elasticModulus_
            >> dummy >> dissipation_;
}

std::string HertzianViscoelasticNormalSpecies::getBaseName() const
{
    return "HertzianViscoelastic";
}

void HertzianViscoelasticNormalSpecies::setElasticModulus(Mdouble elasticModulus)
{
    if (elasticModulus >= 0)
        elasticModulus_ = elasticModulus;
    else
    {
        std::cerr << "Error in setElasticModulus" << std::endl;
        exit(-1);
    }
}

void HertzianViscoelasticNormalSpecies::setElasticModulusAndRestitutionCoefficient(Mdouble elasticModulus, Mdouble rest) {
    // Here is a very nice paper describing contact modelling
    // http://people.ds.cam.ac.uk/jae1001/CUS/research/pfizer/Antypov_Elliott_EPL_2011.pdf
    // see also: https://answers.launchpad.net/yade/+question/235934
    if (elasticModulus >= 0.0 && rest > 0.0 && rest <= 1.0)
    {
        elasticModulus_ = elasticModulus;
        Mdouble logRestSquared = log(rest)*log(rest);
        dissipation_ = sqrt(5.0 * logRestSquared / (logRestSquared + constants::sqr_pi));
        logger(INFO,"Dissipation % set to match restitution coefficient % logE % sqrPi %",dissipation_,rest,log(rest),constants::sqr_pi);
    }
    else
    {
        logger(ERROR,"Error in setElasticModulusAndRestitutionCoefficient");
    }
}

Mdouble HertzianViscoelasticNormalSpecies::getElasticModulus() const
{
    return elasticModulus_;
}

void HertzianViscoelasticNormalSpecies::setDissipation(Mdouble dissipation)
{
    if (dissipation >= 0)
    {
        dissipation_ = dissipation;
    }
    else
    {
        std::cerr << "Error in setDissipation(" << dissipation << ")" << std::endl;
        exit(-1);
    }
}

Mdouble HertzianViscoelasticNormalSpecies::getDissipation() const
{
    return dissipation_;
}

//Mdouble HertzianViscoelasticNormalSpecies::getCollisionTime(Mdouble mass)
//{
//    if (mass <= 0)
//    {
//        std::cerr << "Error in getCollisionTime(Mdouble mass) mass is not set or has an unexpected value, (getCollisionTime(" << mass << "))" << std::endl;
//        exit(-1);
//    }
//    if (elasticModulus_ <= 0)
//    {
//        std::cerr << "Error in getCollisionTime(Mdouble mass) stiffness is not set or has an unexpected value, (getCollisionTime(" << mass << "), with stiffness=" << elasticModulus_ << ")" << std::endl;
//        exit(-1);
//    }
//    if (dissipation_ < 0)
//    {
//        std::cerr << "Error in getCollisionTime(Mdouble mass) dissipation is not set or has an unexpected value, (getCollisionTime(" << mass << "), with dissipation=" << dissipation_ << ")" << std::endl;
//        exit(-1);
//    }
//    Mdouble tosqrt = elasticModulus_ / (.5 * mass) - mathsFunc::square(dissipation_ / mass);
//    if (tosqrt <= 0)
//    {
//        std::cerr << "Error in getCollisionTime(Mdouble mass) values for mass, stiffness and dissipation would lead to an overdamped system, (getCollisionTime(" << mass << "), with stiffness=" << elasticModulus_ << " and dissipation=" << dissipation_ << ")" << std::endl;
//        exit(-1);
//    }
//    return constants::pi / std::sqrt(tosqrt);
//}
//
//Mdouble HertzianViscoelasticNormalSpecies::getRestitutionCoefficient(Mdouble mass)
//{
//    return std::exp(-dissipation_ / mass * getCollisionTime(mass));
//}
//
//Mdouble HertzianViscoelasticNormalSpecies::getMaximumVelocity(Mdouble radius, Mdouble mass)
//{
//    return radius * std::sqrt(elasticModulus_ / (.5 * mass));
//}
//
//void HertzianViscoelasticNormalSpecies::setStiffnessAndRestitutionCoefficient(Mdouble k_, Mdouble eps, Mdouble mass)
//{
//    elasticModulus_ = k_;
//    dissipation_ = -std::sqrt(2.0 * mass * elasticModulus_ / (constants::sqr_pi + mathsFunc::square(log(eps)))) * log(eps);
//}
//
//void HertzianViscoelasticNormalSpecies::setCollisionTimeAndRestitutionCoefficient(Mdouble tc, Mdouble eps, Mdouble mass)
//{
//    dissipation_ = -mass / tc * std::log(eps);
//    elasticModulus_ = .5 * mass * (mathsFunc::square(constants::pi / tc) + mathsFunc::square(dissipation_ / mass));
//}
//
//void HertzianViscoelasticNormalSpecies::setCollisionTimeAndRestitutionCoefficient(Mdouble collisionTime, Mdouble restitutionCoefficient, Mdouble mass1, Mdouble mass2)
//{
//    Mdouble reduced_mass = mass1 * mass2 / (mass1 + mass2);
//    setCollisionTimeAndRestitutionCoefficient(collisionTime, restitutionCoefficient, 2.0 * reduced_mass);
//}

void HertzianViscoelasticNormalSpecies::mix(HertzianViscoelasticNormalSpecies* const S, HertzianViscoelasticNormalSpecies* const T)
{
    elasticModulus_ = average(S->getElasticModulus(), T->getElasticModulus());
    dissipation_ = average(S->getDissipation(), T->getDissipation());
}

Mdouble HertzianViscoelasticNormalSpecies::getCollisionTime(Mdouble particleDiameter, Mdouble particleDensity, Mdouble relativeVelocity) const {
    // Here is a very nice paper describing contact modelling
    // http://people.ds.cam.ac.uk/jae1001/CUS/research/pfizer/Antypov_Elliott_EPL_2011.pdf
    //caution: this function assumes the contact is elastic (no dissipation)
    //Mdouble omega0 = 2.0/constants::sqrt_pi*sqrt(getElasticModulus()/particleDensity)/relativeVelocity;
    //Mdouble omega1 = sqrt(omega0*omega0-getDissipation()*getDissipation());
    return 2.214*pow(mathsFunc::square(particleDensity/getElasticModulus())/relativeVelocity,0.2)*particleDiameter;
}