CGParticleParticleUnitTest.cpp File Reference

#include <Walls/InfiniteWall.h>
#include "Mercury3D.h"
#include "CG/CG.h"
#include "Species/LinearViscoelasticSpecies.h"

Classes
class	TwoParticles

Functions
int	main ()

Function Documentation

main()

int main

(

)

{
    logger(INFO," Simulates a particle-particle collision.\n"
            " Checks cg \n"
            "   - at one instant in time\n"
            "   - standard fields (density and stress)\n"
            "   - for O, Z, and XYZ coordinates\n"
            "   - for both Gauss and Lucy kernel functions\n");
 
    TwoParticles dpm;
    dpm.setName("CGParticleParticleUnitTest");
    dpm.setTimeStep(1e-4);
    dpm.setTimeMax(0);
    dpm.setFileType(FileType::NO_FILE);
 
    //Define coarse graining objects
    Mdouble width = 0.15;
 
    //Unresolved
    auto O = dpm.cgHandler.copyAndAddObject(CG<CGCoordinates::O>());
 
    //Resolved in z at particle centre
    auto Z = dpm.cgHandler.copyAndAddObject(CG<CGCoordinates::Z>(width,1));
    Z->setMin({-1,-1,0.95});
    Z->setMax({1,1,0.95});
 
    //Resolved in z at particle centre with Gauss cg function
    auto G = dpm.cgHandler.copyAndAddObject(CG<CGCoordinates::Z,CGFunctions::Gauss>(width,1));
    G->setMin({-1,-1,0.95});
    G->setMax({1,1,0.95});
 
    //Resolved in z, at particle-particle contact
    auto C = dpm.cgHandler.copyAndAddObject(CG<CGCoordinates::Z>(width,1));
 
    //Resolved in xyz at particle centre
    auto XYZ = dpm.cgHandler.copyAndAddObject(CG<CGCoordinates::XYZ>(width,1));
    XYZ->setMin({-0.95,-1,0.95});
    XYZ->setMax({1.05,1,0.95});
 
    //Resolved in xz, at particle-particle contact
    auto cg2 = dpm.cgHandler.copyAndAddObject(CG<CGCoordinates::XZ,CGFunctions::Gauss>(3*width,30));
    auto cgG = dpm.cgHandler.copyAndAddObject(CG<CGCoordinates::XY,CGFunctions::Gauss>(width,50));
    auto cg = dpm.cgHandler.copyAndAddObject(CG<CGCoordinates::XY>(3*width,50));
 
    dpm.solve();
 
    //A few checks
    logger(INFO,"Checking a few cg parameters");
 
    //Checks density for unresolved cg, rho = M/V = 2/16 = 0.125
    helpers::check(O->getPoint(0).getDensity(),0.125,1e-15, "Average density");
 
    //Checks density at the center of one particle for z-resolved cg, rho = m_2*phi_2(0),
    //assuming the distance between the particles is bigger than the cutoff
    Mdouble phiL0 = 1.25 / width; //peak value of Lucy
    helpers::check(Z->getPoint(0).getDensity(),phiL0/4.0,1e-15, "Z-resolved density at particle centre");
 
    //Check the same for a Gauss cg function
    Mdouble phiG0 = 1.0 / (sqrt_2 * sqrt_pi * erf(3.0/sqrt_2))/width; //peak value of Gaussian cutoff at 3*width
    helpers::check(G->getPoint(0).getDensity(),phiG0/4.0,1e-15, "Z-resolved density for Gaussian CG");
 
    //Check the same for fully-resolved cg
    Mdouble phi30 = 105.0/16.0/pi / mathsFunc::cubic(width); //peak value of Lucy in 3D
    helpers::check(XYZ->getPoint(0).getDensity(),phi30,1e-11, "Fully-resolved density at particle centre");
 
 
    //Checks if the unresolved cg returns the right value for stress, sigma_zz = f_12*r_12/V
    Mdouble distance = Vec3D::getDistance(dpm.particleHandler.getObject(0)->getPosition(),dpm.particleHandler.getObject(1)->getPosition());
    Mdouble overlap = 2.0-distance;
    helpers::check(O->getPoint(0).getContactStress().trace(),2e5*overlap*distance/16,1e-11, "Average stress");
 
    //Checks if z-resolved cg returns the right value for stress at the center of the contact,
    //sigma_zz = f_12*r_12/r_12z/A, assuming the cutoff is smaller than the branch vector
    Mdouble distanceZ = dpm.particleHandler.getObject(1)->getPosition().Z-dpm.particleHandler.getObject(0)->getPosition().Z;
    helpers::check(C->getPoint(0).getContactStress().trace(),2e5*overlap*distance/distanceZ/4,1e-11, "Z-resolved stress at contact point");
 
    return 0;
}

References DPMBase::cgHandler, helpers::check(), BaseHandler< T >::copyAndAddObject(), mathsFunc::cubic(), e(), G, Vec3D::getDistance(), BaseHandler< T >::getObject(), BaseInteractable::getPosition(), INFO, logger, NO_FILE, DPMBase::particleHandler, constants::pi, DPMBase::setFileType(), DPMBase::setName(), DPMBase::setTimeMax(), DPMBase::setTimeStep(), DPMBase::solve(), constants::sqrt_2, constants::sqrt_pi, XYZ, Z, and Vec3D::Z.