// constructor
public SoftSpheres(ParticleEnsemble pParticleSet)
{
epsilon=10.0;
// allocate vectors holding positions & forces
LJxforces = new double[pParticleSet.GetMaxNumberOfParticles()];
LJyforces = new double[pParticleSet.GetMaxNumberOfParticles()];
// allocate vector holding cutoff distance for calculating Wall-Particle interactions
WallDistance = new double[pParticleSet.GetMaxNumberOfParticles()];
// allocate vector holding cutoff distance for calculating particle-particle interaction
//Mat_DP tmp(0.0,pParticleSet->GetMaxNumberOfParticles(),pParticleSet->GetMaxNumberOfParticles());
MinimumDistance = new DPMatrix(0, pParticleSet.GetMaxNumberOfParticles(),pParticleSet.GetMaxNumberOfParticles());
// allocate vectors holding particle-particle LJ energy terms
LJenergyTermA = new DPMatrix(0, pParticleSet.GetMaxNumberOfParticles(),pParticleSet.GetMaxNumberOfParticles()); // =tmp;
LJenergyTermB = new DPMatrix(0, pParticleSet.GetMaxNumberOfParticles(), pParticleSet.GetMaxNumberOfParticles()); // =tmp;
LJgradientTermA = new DPMatrix(0, pParticleSet.GetMaxNumberOfParticles(), pParticleSet.GetMaxNumberOfParticles()); // =tmp;
LJgradientTermB = new DPMatrix(0, pParticleSet.GetMaxNumberOfParticles(), pParticleSet.GetMaxNumberOfParticles()); // =tmp;
CalculateEnergyTerms(pParticleSet);
// calculate initial forcefield
CalculateForceField(pParticleSet);
}
public override void UpdateEnergyTerms(ParticleEnsemble ensemble)
{
for (int i = 0; i < ensemble.GetNumberOfParticles(); ++i)
{
for (int j = (i + 1); j < ensemble.GetNumberOfParticles(); ++j)
{
double MinDistance = 2.0 * (ensemble.GetParticleRadius(i) + ensemble.GetParticleRadius(j));
MinimumDistance[i, j] = MinDistance;
MinimumDistance[j, i] = MinDistance;
LJenergyTermA[i, j] = epsilon * Math.Pow(MinDistance, 12.0);
LJenergyTermA[j, i] = LJenergyTermA[i, j];
LJenergyTermB[i, j] = -2.0 * epsilon * Math.Pow(MinDistance, 6.0);
LJenergyTermB[j, i] = LJenergyTermB[i, j];
LJgradientTermA[i, j] = -12.0 * LJenergyTermA[i, j];
LJgradientTermA[j, i] = LJgradientTermA[i, j];
LJgradientTermB[i, j] = -6.0 * LJenergyTermB[i, j];
LJgradientTermB[j, i] = LJgradientTermB[i, j];
}
}
}
public override void CalculateForceField(ParticleEnsemble ensemble)
{
//variable declarations
double posXi, posYi;
double posXj, posYj;
double LJxf, LJyf;
double ijSeparation = 0.0, LJforce = 0.0, PotentialEnergy = 0.0;
int j, kk, ctr, dimensions = 2;
//variable initializations
int BoxHeight = ensemble.GetBoxHeight();
int BoxWidth = ensemble.GetBoxWidth();
double MaxForce = ensemble.GetMaxForceThreshold();
double MinForce = -1.0 * (ensemble.GetMaxForceThreshold());
// initialize vectors holding forces
for (int i = 0; i < ensemble.GetNumberOfParticles(); ++i)
{
LJxforces[i]=0.0;
LJyforces[i]=0.0;
}
ensemble.ResetAllParticlesNotWithinRange();
for (int i = 0; i < ensemble.GetNumberOfParticles(); ++i)
{
for (j = (i + 1); j < ensemble.GetNumberOfParticles(); ++j)
{
// get the interparticle separation distances
ijSeparation = ensemble.GetInterParticleSeparation(i, j);
// update the radial distribution function
// pParticleSet->UpdateRadialDistributionFunction((int)(ijSeparation));
double cutoffDistance = MinimumDistance[i, j];
if (ijSeparation < cutoffDistance) {
// for each particle, change the appropriate element of the setWithinRangeOfAnotherParticle vector to true
posXi = ensemble.GetXParticlePosition(i);
posYi = ensemble.GetYParticlePosition(i);
posXj = ensemble.GetXParticlePosition(j);
posYj = ensemble.GetYParticlePosition(j);
// PotentialEnergy += LJenergyTermA[i][j]/(pow(ijSeparation,12.0))+LJenergyTermB[i][j]/pow(ijSeparation,6.0)+epsilon;
LJforce = (posXj - posXi) * (LJgradientTermA[i, j] / Math.Pow(ijSeparation, 13.0) + LJgradientTermB[i, j] / Math.Pow(ijSeparation, 7.0)) / ijSeparation;
if (Math.Abs(LJforce) > MaxForce || Math.Abs(LJforce) < MinForce) { LJforce = 0.0; } // error check for real-time stability...
else if(double.IsNaN(LJforce) || double.IsInfinity(LJforce)){LJforce = 0.0;} // error check for real-time stability...
LJxforces[i] += LJforce;
LJxforces[j] += -1.0*LJforce;
// cout << "x "<< i << " " << j << " " << LJforce << endl;
// cout << "i " << i << " LJxforces[i] " << LJxforces[i] << " j " << j << " LJxforces[j] " << LJxforces[j] << endl;
// cout << "xi:=" << posXi << ";" << "xj:=" << posXj << ";" << "yi:=" << posYi << ";" << "yj:=" << posYj << ";" << LJxforces[i] << endl;
LJforce = (posYj - posYi) * (LJgradientTermA[i, j] / Math.Pow(ijSeparation, 13.0) + LJgradientTermB[i, j] / Math.Pow(ijSeparation, 7.0)) / ijSeparation;
if (Math.Abs(LJforce) > MaxForce || Math.Abs(LJforce) < MinForce) { LJforce = 0.0; } // error check for real-time stability...
else if (double.IsNaN(LJforce) || double.IsInfinity(LJforce)) { LJforce = 0.0; } // error check for real-time stability...
LJyforces[i] += LJforce;
LJyforces[j] += -1.0*LJforce;
ensemble.SetParticlesWithinRange(i, j);
ensemble.SetParticlesWithinRange(j, i);
// cout << i << " " << j << endl;
}
//else{
//ensemble.SetParticlesNotWithinRange(i, j);
//ensemble.SetParticlesNotWithinRange(j, i);
//}
}
}
// set the forces in the Particle Ensemble Object
ensemble.AddXForces(LJxforces);
ensemble.AddYForces(LJyforces);
// set the potential energy
ensemble.AddPotentialEnergy(PotentialEnergy);
}
public abstract void CalculateForceField(ParticleEnsemble ensemble);
public abstract void UpdateEnergyTerms(ParticleEnsemble ensemble);
public abstract void CalculateEnergyTerms(ParticleEnsemble ensemble);