force_test_demo.cpp File Reference

#include "DPMBase.h"
#include "Particles/BaseParticle.h"
#include "Walls/InfiniteWall.h"
#include "Species/Species.h"
#include "Species/LinearViscoelasticSlidingFrictionSpecies.h"

Go to the source code of this file.

Classes
class	particle_particle_collision
class	wall_particle_collision

Functions
void	particle_particle_test ()
void	wall_particle_test ()
int	main (int argc UNUSED, char *argv[] UNUSED)

Function Documentation

int main	(	int argc	UNUSED,
		char *argv[]	UNUSED
	)

Definition at line 316 of file force_test_demo.cpp.

References particle_particle_test(), and wall_particle_test().

                                               {
    
    std::cout << std::endl << "note: analytic values are only asymptotically correct as delta->0" << std::endl;
    particle_particle_test();
    wall_particle_test();
    
    return 0;
}

void particle_particle_test

(

)

Definition at line 183 of file force_test_demo.cpp.

References particle_particle_collision::en, particle_particle_collision::getCollisionTime(), RNG::getRandomNumber(), particle_particle_collision::getRelativeVelocityComponents(), particle_particle_collision::initialNormalRelativeVelocity, particle_particle_collision::initialTangentialRelativeVelocity, particle_particle_collision::m12, constants::pi, DPMBase::random, Files::setName(), RNG::setRandomSeed(), particle_particle_collision::setupInitialConditions(), DPMBase::solve(), particle_particle_collision::species, mathsFunc::square(), and particle_particle_collision::tc.

Referenced by main().

{
    std::cout << std::endl << "testing particle-particle collisions ..." << std::endl << std::endl;

    particle_particle_collision problem;
    
    problem.random.setRandomSeed(5);

    problem.setupInitialConditions();
    Mdouble normalRelativeVelocity, tangentialRelativeVelocity, analyticTangentialRelativeVelocity;
    
    std::cout << "5: without tangential forces" << std::endl;
    problem.setName("force_test5");
    problem.solve();
    problem.getRelativeVelocityComponents(normalRelativeVelocity, tangentialRelativeVelocity);
    std::cout << "tangentialRelativeVelocity: analytic=" << problem.initialTangentialRelativeVelocity << ", simulation=" << tangentialRelativeVelocity << std::endl;
    std::cout << "normalRelativeVelocity: analytic:" << -problem.en*problem.initialNormalRelativeVelocity << ", simulation=" << normalRelativeVelocity << std::endl;

    //problem.setAppend_to_files(true);

    std::cout << "6: with Coulomb friction" << std::endl;
    Mdouble mu = problem.random.getRandomNumber(0.0,1.0);
    problem.species->setSlidingFrictionCoefficient(mu);
    problem.species->setSlidingDissipation(1e20);
    //problem.species->setSlidingStiffness(0.0);
    problem.setName("force_test6");
    problem.solve();
    problem.getRelativeVelocityComponents(normalRelativeVelocity, tangentialRelativeVelocity);
    analyticTangentialRelativeVelocity = std::max(0.0,problem.initialTangentialRelativeVelocity + mu*3.5*(1+problem.en)*problem.initialNormalRelativeVelocity);
    std::cout << "tangentialRelativeVelocity: analytic=" << analyticTangentialRelativeVelocity << ", simulation=" << tangentialRelativeVelocity << std::endl;
    std::cout << "normalRelativeVelocity: analytic:" << -problem.en*problem.initialNormalRelativeVelocity << ", simulation=" << normalRelativeVelocity << std::endl;
    
    std::cout << "7: with Coulomb friction, spring activated" << std::endl;
    problem.species->setSlidingStiffness(1.0);
    //problem.species->setSlidingDissipation(1);
    problem.setName("force_test7");
    problem.solve();
    std::cout << "tangentialRelativeVelocity: analytic=" << analyticTangentialRelativeVelocity << ", simulation=" << tangentialRelativeVelocity << std::endl;
    std::cout << "normalRelativeVelocity: analytic:" << -problem.en*problem.initialNormalRelativeVelocity << ", simulation=" << normalRelativeVelocity << std::endl;

    std::cout << "8: with tangential viscous force" << std::endl;
    Mdouble et = problem.random.getRandomNumber(-1.0,0.0);
    problem.species->setSlidingFrictionCoefficient(1e20);
    problem.species->setSlidingDissipation(-log(-et)/(2.0*problem.tc) /3.5 * 2.0 * problem.m12);
    problem.species->setSlidingStiffness(0.0);
    problem.setName("force_test8");
    problem.solve();
    problem.getRelativeVelocityComponents(normalRelativeVelocity, tangentialRelativeVelocity);
    analyticTangentialRelativeVelocity = problem.initialTangentialRelativeVelocity * exp(-2.0*3.5*problem.species->getSlidingDissipation()/(2.0*problem.m12) * problem.getCollisionTime(2.0*problem.m12));
    std::cout << "tangentialRelativeVelocity: analytic=" << analyticTangentialRelativeVelocity << ", simulation=" << tangentialRelativeVelocity << std::endl;
    std::cout << "normalRelativeVelocity: analytic:" << -problem.en*problem.initialNormalRelativeVelocity << ", simulation=" << normalRelativeVelocity << std::endl;
    
    std::cout << "9: with tangential elastic force" << std::endl;
    Mdouble et2 = problem.random.getRandomNumber(0.0,1.0);
    problem.species->setSlidingFrictionCoefficient(1e20);
    problem.species->setSlidingDissipation(0.0);
    problem.species->setSlidingStiffness(problem.species->getStiffness()/3.5*mathsFunc::square(acos(-et2)/constants::pi));
    problem.setName("force_test9");
    problem.solve();
    problem.getRelativeVelocityComponents(normalRelativeVelocity, tangentialRelativeVelocity);
    analyticTangentialRelativeVelocity = problem.initialTangentialRelativeVelocity * cos(sqrt(problem.species->getSlidingStiffness()/problem.m12*3.5)* problem.getCollisionTime(2.0*problem.m12));
    std::cout << "tangentialRelativeVelocity: analytic=" << analyticTangentialRelativeVelocity << ", simulation=" << tangentialRelativeVelocity << std::endl;
    std::cout << "normalRelativeVelocity: analytic:" << -problem.en*problem.initialNormalRelativeVelocity << ", simulation=" << normalRelativeVelocity << std::endl;

}

void wall_particle_test

(

)

Definition at line 249 of file force_test_demo.cpp.

References particle_particle_collision::en, particle_particle_collision::getCollisionTime(), RNG::getRandomNumber(), wall_particle_collision::getRelativeVelocityComponents(), particle_particle_collision::initialNormalRelativeVelocity, particle_particle_collision::initialTangentialRelativeVelocity, particle_particle_collision::m12, constants::pi, DPMBase::random, Files::setName(), wall_particle_collision::setupInitialConditions(), DPMBase::solve(), particle_particle_collision::species, mathsFunc::square(), and particle_particle_collision::tc.

Referenced by main().

{
    std::cout << std::endl << "testing wall-particle collisions ..." << std::endl << std::endl;
    
    srand(5);
    
    wall_particle_collision problem;
    problem.setupInitialConditions();

    Mdouble normalRelativeVelocity, tangentialRelativeVelocity, analyticTangentialRelativeVelocity;
    
    //problem.setAppend_to_files(true);
    
    std::cout << "0: without tangential forces" << std::endl;
    problem.setName("force_test0");
    problem.solve();
    
    problem.getRelativeVelocityComponents(normalRelativeVelocity, tangentialRelativeVelocity);
    std::cout << "tangentialRelativeVelocity: analytic=" << problem.initialTangentialRelativeVelocity << ", simulation=" << tangentialRelativeVelocity << std::endl;
    std::cout << "normalRelativeVelocity: analytic:" << -problem.en*problem.initialNormalRelativeVelocity << ", simulation=" << normalRelativeVelocity << std::endl;

    std::cout << "1: with Coulomb friction" << std::endl;
    Mdouble mu = problem.random.getRandomNumber(0.0,1.0);
    problem.species->setSlidingFrictionCoefficient(mu);
    problem.species->setSlidingDissipation(1e20);
    problem.species->setSlidingStiffness(0.0);
    problem.setName("force_test1");
    problem.solve();
    problem.getRelativeVelocityComponents(normalRelativeVelocity, tangentialRelativeVelocity);
    analyticTangentialRelativeVelocity = std::max(0.0,problem.initialTangentialRelativeVelocity + mu*3.5*(1+problem.en)*problem.initialNormalRelativeVelocity);
    std::cout << "tangentialRelativeVelocity: analytic=" << analyticTangentialRelativeVelocity << ", simulation=" << tangentialRelativeVelocity << std::endl;
    std::cout << "normalRelativeVelocity: analytic:" << -problem.en*problem.initialNormalRelativeVelocity << ", simulation=" << normalRelativeVelocity << std::endl;

    std::cout << "2: with Coulomb friction, spring activated" << std::endl;
    problem.species->setSlidingStiffness(1.0);
    problem.setName("force_test2");
    problem.solve();
    std::cout << "tangentialRelativeVelocity: analytic=" << analyticTangentialRelativeVelocity << ", simulation=" << tangentialRelativeVelocity << std::endl;
    std::cout << "normalRelativeVelocity: analytic:" << -problem.en*problem.initialNormalRelativeVelocity << ", simulation=" << normalRelativeVelocity << std::endl;

    std::cout << "3: with tangential viscous force" << std::endl;
    Mdouble et = problem.random.getRandomNumber(-1.0,0.0);
    problem.species->setSlidingFrictionCoefficient(1e20);
    problem.species->setSlidingDissipation(-log(-et)/(2.0*problem.tc) /3.5 * 2.0 * problem.m12);
    problem.species->setSlidingStiffness(0.0);
    problem.setName("force_test3");
    problem.solve();
    problem.getRelativeVelocityComponents(normalRelativeVelocity, tangentialRelativeVelocity);
    analyticTangentialRelativeVelocity = problem.initialTangentialRelativeVelocity * exp(-2.0*3.5*problem.species->getSlidingDissipation()/(2.0*problem.m12) * problem.getCollisionTime(2.0*problem.m12));
    std::cout << "tangentialRelativeVelocity: analytic=" << analyticTangentialRelativeVelocity << ", simulation=" << tangentialRelativeVelocity << std::endl;
    std::cout << "normalRelativeVelocity: analytic:" << -problem.en*problem.initialNormalRelativeVelocity << ", simulation=" << normalRelativeVelocity << std::endl;

    std::cout << "4: with tangential elastic force" << std::endl;
    Mdouble et2 = problem.random.getRandomNumber(0.0,1.0);
    problem.species->setSlidingFrictionCoefficient(1e20);
    problem.species->setSlidingDissipation(0.0);
    problem.species->setSlidingStiffness(problem.species->getStiffness()/3.5*mathsFunc::square(acos(-et2)/constants::pi));
    problem.setName("force_test4");
    problem.solve();
    problem.getRelativeVelocityComponents(normalRelativeVelocity, tangentialRelativeVelocity);
    analyticTangentialRelativeVelocity = problem.initialTangentialRelativeVelocity * cos(sqrt(problem.species->getSlidingStiffness()/problem.m12*3.5)* problem.getCollisionTime(2.0*problem.m12));
    std::cout << "tangentialRelativeVelocity: analytic=" << analyticTangentialRelativeVelocity << ", simulation=" << tangentialRelativeVelocity << std::endl;
    std::cout << "normalRelativeVelocity: analytic:" << -problem.en*problem.initialNormalRelativeVelocity << ", simulation=" << normalRelativeVelocity << std::endl;
}