private void SetupForTesting(int Nparticles)
{
double gradScaleFactor = 3000.0;
double MinRad = 40.0;
double MaxRad = 50.0;
List<string> FFtype = new List<string>(new string[] { "SoftSpheres", "ExternalField" });
ParticleStaticObjects.AtomPropertiesDefinition.Clear();
ParticleStaticObjects.AtomPropertiesDefinition.AddParticleDefinition("Hydrogen", 2, unchecked((int)0xc00A32FF), 0, 50); // neon blue
ParticleStaticObjects.AtomPropertiesDefinition.AddParticleDefinition("Oxygen", 4, unchecked((int)0xc0FF0A32), 1, 49); // red
ParticleStaticObjects.AtomPropertiesDefinition.AddParticleDefinition("Neon", 6, unchecked((int)0xc0320AFF), 2, 45); // purple
ParticleStaticObjects.AtomPropertiesDefinition.AddParticleDefinition("Zinc", 9.2, unchecked((int)0xc026D8FF), 3, 43); // sky blue // 0xc032FF0A, 3, 43); // green
ParticleStaticObjects.AtomPropertiesDefinition.AddParticleDefinition("Iron", 12.6, unchecked((int)0xc0FF320A), 4, 38); // orange
ParticleStaticObjects.ReSeedRandom(42);
Ensemble1 = new ParticleEnsemble(Nparticles, MinRad, MaxRad, FFtype, m_SizeY, m_SizeX, gradScaleFactor);
Field = new ExternalField(Ensemble1);
double[] background = new double[m_NumberOfPixels];
for (int i = 0; i < m_NumberOfPixels; i++)
{
background[i] = 512;
}
Field.IncrementGrabberCalls(); // increment the number of grabber calls
Field.BackgroundCalibration(m_NumberOfPixels, background); // in order to simply set the background to zero
Field.SetCalibrating(false);
}
/// <summary>
/// Velocity verlet routine to propagate the particle ensemble
/// </summary>
/// <param name="Height"></param>
/// <param name="Width"></param>
/// <param name="pExternalField"></param>
public void VelocityVerletPropagation(int Height, int Width, ExternalField pExternalField)
{
int i, kk;
double V = 0.0, T = 0.0, dt, pxnew, pynew, factor;
m_AllPositionsUnchangedFromLastStep = true;
m_BoxWidth = Width;
m_BoxHeight = Height;
if (m_NumberOfParticlesChangedFlag)
{
#region Number Of Particles has been adjusted
m_NumberOfParticlesChangedFlag = false;
if (m_NumberOfParticlesIsGreaterFlag)
{
for (kk = 0; kk < NumberOfForceFieldObjects; ++kk)
{
// calculate the ij energy terms for particle set including the new ones
GetForceFieldObject(kk).UpdateEnergyTerms(this);
}
}
#endregion
}
else
{
#region Regular Time Step
#region Increment Time Steps
// Timestep = 1.0/(double)ofGetFrameRate();
m_Timestep = 0.005;
dt = m_Timestep;
// increment ParticleEnsemble Private data member step
++m_Step;
#endregion
#region Berendsen Velocity Rescaling
if (m_BerendsenThermostat)
{
// Berendsen Thermostat
BerendsenVelocityRescaling();
}
#endregion
#region Move all particles
// this loop uses verlet scheme (VV) to propagate the positions forward one step
for (i = 0; i < NumberOfParticles; ++i)
{
Particle particlei = GetParticle(i);
particlei.PositionLast = particlei.Position;
factor = 0.5 * dt * dt / particlei.Mass;
pxnew = particlei.Position.X + particlei.Velocity.X * dt + particlei.Force.X * factor;
pynew = particlei.Position.Y + particlei.Velocity.Y * dt + particlei.Force.Y * factor;
#region Check for colitions with the wall (left or right)
if (pxnew > particlei.Radius && pxnew < (m_BoxWidth - particlei.Radius))
{
particlei.Position.X = pxnew;
}
else
{
// this is to reflect off the walls; added by DRG in lieu of soft walls to improve real time stability... not part of a standard VV scheme
particlei.Position.X = particlei.PositionLast.X;
particlei.Velocity.X = -1.0 * particlei.Velocity.X;
#if DEBUG
if (particlei.Velocity.IsNanOrInfinate == true)
{
throw new Exception("Particle Velocity Is Nan Or Infinate");
}
#endif
particlei.WasReflectedByWall = true;
CalculateParticleVelocitiesInXWallFrame(i);
}
#endregion
#region Check for colitions with the wall (top or bottom)
if (pynew > particlei.Radius && pynew < (m_BoxHeight - particlei.Radius))
{
// this the standard VV code here
particlei.Position.Y = pynew;
}
else
{
// this is to reflect off the walls; added by DRG in lieu of soft walls to improve real time stability... not part of a standard VV scheme
particlei.Position.Y = particlei.PositionLast.Y;
particlei.Velocity.Y = -1.0 * particlei.Velocity.Y;
#if DEBUG
if (particlei.Velocity.IsNanOrInfinate == true)
{
throw new Exception("Particle Velocity Is Nan Or Infinate");
}
#endif
particlei.WasReflectedByWall = true;
CalculateParticleVelocitiesInYWallFrame(i);
}
#endregion
// check whether all the positions are changed from the last step
if (particlei.Position.Y != particlei.PositionLast.Y || particlei.Position.X != particlei.PositionLast.X)
{
m_AllPositionsUnchangedFromLastStep = false;
}
}
#endregion
#region If all the particles have frozen then we need to rerandomise (should be rare)
// this is a stability measure; if the frame is frozen wrt to the previous frame,
if (m_AllPositionsUnchangedFromLastStep)
{
// adjust particle positions to eliminate overlap - this can cause the sim to freeze
EliminateParticleOverlap(m_BoxHeight, m_BoxWidth);
for (i = 0; i < NumberOfParticles; ++i)
{
Particle particlei = GetParticle(i);
// then we zero out the forces and velocities & repropagate the positions
particlei.Force.X = 0;
particlei.Force.Y = 0;
particlei.PositionLast.X = particlei.Position.X;
particlei.PositionLast.Y = particlei.Position.Y;
particlei.Position.X = particlei.Position.X + particlei.Velocity.X * dt + (particlei.Force.X / particlei.Mass) * dt * dt * 0.5;
particlei.Position.Y = particlei.Position.Y + particlei.Velocity.Y * dt + (particlei.Force.Y / particlei.Mass) * dt * dt * 0.5;
}
m_AllPositionsUnchangedFromLastStep = false;
}
#endregion
#region Determin Inter-particle collions
UpdateInterParticleSeparations();
#endregion
#region Calculate Force Fields
if (pExternalField != null)
{
pExternalField.CalculateForceField(this);
}
if (GetForceFieldObject(0).ForceFieldType == "HardSphereForceField")
{
GetForceFieldObject(0).CalculateForceField(this);
}
else
{
for (i = 0; i < NumberOfParticles; ++i)
{
Particle particlei = GetParticle(i);
// save the present forces to t-1 vectors
particlei.ForceLast.X = particlei.Force.X;
particlei.ForceLast.Y = particlei.Force.Y;
}
// zero out the force vectors & potential energy
ZeroForces();
PotentialEnergy = 0.0;
for (kk = 0; kk < NumberOfForceFieldObjects; ++kk)
{ // calculate & set the forces at the new positions
GetForceFieldObject(kk).CalculateForceField(this);
}
for (i = 0; i < NumberOfParticles; ++i)
{
Particle particlei = GetParticle(i);
// use VV scheme to propagate the velocities forward
factor = dt * 0.5 / particlei.Mass;
particlei.Velocity.X = particlei.Velocity.X + (particlei.Force.X + particlei.ForceLast.X * factor);
particlei.Velocity.Y = particlei.Velocity.Y + (particlei.Force.Y + particlei.ForceLast.Y * factor);
#if DEBUG
if (particlei.Velocity.IsNanOrInfinate == true)
{
throw new Exception("Particle Velocity Is Nan Or Infinate");
}
#endif
}
// see whether any collisions occurred
DetermineIfCollisionsOccurred();
}
#endregion
#endregion
}
}
