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/////////////////////////////////////////////////////////////
// //
// Copyright (c) 2003-2014 by The University of Queensland //
// Centre for Geoscience Computing //
// http://earth.uq.edu.au/centre-geoscience-computing //
// //
// Primary Business: Brisbane, Queensland, Australia //
// Licensed under the Open Software License version 3.0 //
// http://www.apache.org/licenses/LICENSE-2.0 //
// //
/////////////////////////////////////////////////////////////
#include "LinearDashpotInteraction.h"
// --- system includes ---
#include <iostream>
// --- member functions for interaction group parameter class ---
//! default constructor
CLinearDashpotIGP::CLinearDashpotIGP(): AIGParam(), m_damp(0.0), m_cutoff(1.0)
{}
/*!
constructor with parameters
\param name the name of the interaction group
\param damp the damping coefficient
\param cutoff the interaction range, relative to the sum of the particle radii
*/
CLinearDashpotIGP::CLinearDashpotIGP(const std::string& name,double damp, double cutoff)
: AIGParam(name), m_damp(damp), m_cutoff(cutoff)
{}
// --- function of interaction class ---
CLinearDashpotInteraction::CLinearDashpotInteraction(CParticle* p1,CParticle* p2, const CLinearDashpotIGP& param) : APairInteraction(p1,p2)
{
// calc. cross section - 2D / 3D
double r_avg=0.5*(m_p1->getRad()+m_p2->getRad());
if(CParticle::getDo2dCalculations()){
m_cross_section=2.0*r_avg;
} else {
m_cross_section=M_PI*r_avg*r_avg;
}
// set parameters
m_cutoff=param.m_cutoff;
m_damp=param.m_damp;
m_force=Vec3(0.0,0.0,0.0);
}
/*!
calculate forces
*/
void CLinearDashpotInteraction::calcForces()
{
// calc distance -> needed to check if particles interact
Vec3 D=m_p1->getPos()-m_p2->getPos();
double dist_sq=D*D;
// calc cutoff distance -> could be cached
double cut_dist=m_cutoff*(m_p1->getRad()+m_p2->getRad());
if(dist_sq<(cut_dist*cut_dist)){
// velocity difference
Vec3 dvel=m_p1->getVel()-m_p2->getVel();
// strain rate
Vec3 eps_dot=dvel/sqrt(dist_sq);
m_force=eps_dot*m_damp*m_cross_section;
// apply force at particle centers
m_p2->applyForce(m_force,m_p2->getPos());
m_p1->applyForce(-1.0*m_force,m_p1->getPos());
}
m_cpos=(m_p1->getPos()+m_p2->getPos())*0.5;
}
/*!
"field function" returning force currently exerted by interaction
*/
Vec3 CLinearDashpotInteraction::getForce() const
{
return m_force;
}
/*!
Get the particle member function which returns a scalar field of a given name.
\param name the name of the field
*/
CLinearDashpotInteraction::ScalarFieldFunction CLinearDashpotInteraction::getScalarFieldFunction(const string& name)
{
CLinearDashpotInteraction::ScalarFieldFunction sf;
if (name=="count"){
sf=&CLinearDashpotInteraction::Count;
} else {
sf=NULL;
std::cerr << "ERROR - invalid name for interaction scalar access function " << name << " in LinearDashpotInteraction" << std::endl;
}
return sf;
}
/*!
Get the particle member function which returns a vector field of a given name.
\param name the name of the field
*/
CLinearDashpotInteraction::VectorFieldFunction CLinearDashpotInteraction::getVectorFieldFunction(const string& name)
{
CLinearDashpotInteraction::VectorFieldFunction vf;
if (name=="force"){
vf=&CLinearDashpotInteraction::getForce;
} else {
vf=NULL;
std::cerr << "ERROR - invalid name for interaction vector access function " << name << " in LinearDashpotInteraction" << endl;
}
return vf;
}
/*!
dummy
*/
CLinearDashpotInteraction::CheckedScalarFieldFunction CLinearDashpotInteraction::getCheckedScalarFieldFunction(const string& name)
{
CLinearDashpotInteraction::CheckedScalarFieldFunction csf;
csf=NULL;
cerr << "ERROR - invalid name for interaction vector access function " << name << " in LinearDashpotInteraction" << endl;
return csf;
}
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