//package org.opensourcephysics.sip.ch08.md; import org.opensourcephysics.controls.*; import org.opensourcephysics.frames.*; import org.opensourcephysics.display.GUIUtils; /** * LJParticlesApp simulates a creates either an LJParticles (granular particles interacting via a Lennard-Jones potential) * or a SiloParticles object (granular particles inside of a silo with a hole of variable size in the base) * * Daniel Costantino, based on LJParticlesApp by * @author Jan Tobochnik, Wolfgang Christian, Harvey Gould * @version 1.0 revised 03/28/05, 3/29/05 */ public class LJParticlesApp extends AbstractSimulation { LJParticles md; // the type of object will be determined by a user input PlotFrame temperatureData = new PlotFrame("time", "temperature", "Mean Temperature"); // plots the temperature (average kinetic energy) of the system) PlotFrame numberPlot = new PlotFrame("time", "Number of Particles", "Number of Particles"); // plots the number of particles as a function of time (only for a SiloParticles object though //PlotFrame pressureData = new PlotFrame("time", "PA/NkT", "Mean Pressure"); // this shouldn't be necessary but in case I decide to play with it later, I left it in HistogramFrame xVelocityHistogram = new HistogramFrame("vx", "H(vx)", "X-Velocity Histogram"); HistogramFrame yVelocityHistogram = new HistogramFrame("vy", "H(vy)", "Y-Velocity Histogram"); HistogramFrame speedHistogram = new HistogramFrame("speed", "H(speed)", "Speed Histogram"); // plot histograms of the x and y components of velocity as well as its magnitude DisplayFrame display = new DisplayFrame("x", "y", "Lennard-Jones Particles"); // plot the position of all the particles (as well as the hole in a silo if we're in one) double temperature = 0; // the temperature of the system boolean silo; // keeps track of if the simulation is for a silo or not //initialize() reads in the user inputs and then initializes md according to the method in LJParticles() //-------------------------------------------------------------------------------------------------------------------------- public void initialize() { display.clearDrawables();// each time, the "LJ Particles" frame should be cleared silo = control.getBoolean("Silo Set-Up?"); // check to see if the user wants to simulate particles in a silo, and create md accordingly if(!silo) { md = new LJParticles(); } else { md = new SiloParticles(); } md.isSilo = silo; md.N = control.getInt("Number of Particles"); // the number of particles in the simulation md.initialKineticEnergy = control.getDouble("initial kinetic energy per particle"); // the initial kinetic energy per particle md.Lx = control.getDouble("Lx"); // the width and md.Ly = control.getDouble("Ly"); // height of the grain's container md.rCutOff = control.getDouble("CutOff Factor / 2^(1/6)"); // how far away particles can interact with each other md.rCutOff = md.rCutOff * Math.pow(2, 1/6); // default is the minimum of the Lennard-Jones potential md.gamma = control.getDouble("Damping Factor"); // coefficient of the damping force to remove energy from collisions md.giveRandom = control.getBoolean("Give Random Kicks?"); md.desiredKE = control.getDouble("Desired KE per particle"); // a kinetic energy to be added if the system // allows kicks of energy to be added md.stepsBetween = control.getInt("Find Neighbor Time"); // how often the system should look for which particles are // close to one another md.dt = control.getDouble("dt"); // size of the time step md.holeDiam = control.getDouble("Aperture Size"); // how large the silo's aperture should be, if the simulation is // modeling a silo md.holeDiam = md.holeDiam * 2 * md.rCutOff; // convert the aperture into grain diameters md.nuclear = control.getBoolean("Have Close CutOff?"); // artificial controls to make sure the temperature of the md.bootstrap = control.getBoolean("Artificial Temperature Reduction?"); // system does not explode md.theMatrix = control.getBoolean("Allow Time Slow Down?"); md.initialize(); display.addDrawable(md); display.setPreferredMinMax(0, md.Lx, 0, md.Ly); xVelocityHistogram.setBinWidth(2*md.initialKineticEnergy/md.N); yVelocityHistogram.setBinWidth(2*md.initialKineticEnergy/md.N); speedHistogram.setBinWidth(2*md.initialKineticEnergy/md.N); // this makes the bin-size for the histograms // 2 * initialKE / N (allows for resolution of // vAveInitial^2 / N } //doStep() advances the time step by calling step() in LJParticles and appends the new information onto the appropriate //plots--------------------------------------------------------------------------------------------------------------------- public void doStep() { control.clearMessages(); md.step(xVelocityHistogram, yVelocityHistogram, speedHistogram); temperature = md.getMeanTemperature(); temperatureData.append(0, md.t, temperature); // graph the temperature at this time temperature = 1000 * temperature; temperature = temperature + 0.5; temperature = (int) temperature; temperature = temperature / 1000; control.println("Temperature = "+temperature); // output the temperature with only the first few digits after // the decimal point control.println("Time = "+md.t); if(silo) { numberPlot.append(0, md.t, md.nPart); // if it's a silo problem, graph the number of particles in the } // container } //stop() takes care of printing statistics about the run once it is done //------------------------------------------------------------------------------------------------------------------------ public void stop() { control.println("Density = "+decimalFormat.format(md.rho)); control.println("Number of time steps = "+md.steps); control.println("Time step dt = "+decimalFormat.format(md.dt)); control.println("= "+decimalFormat.format(md.getMeanTemperature())); control.println(" = "+decimalFormat.format(md.getMeanEnergy())); } //startRunning() reads in the adjustable parameters and checks to see if they've changed //----------------------------------------------------------------------------------------------------------------------- public void startRunning() { md.dt = control.getDouble("dt"); double Lx = control.getDouble("Lx"); double Ly = control.getDouble("Ly"); double desiredKE = control.getDouble("Desired KE per particle"); if((Lx!=md.Lx)||(Ly!=md.Ly) || (desiredKE != md.desiredKE)) { // if any of the adjustables have changed, read in the new values and calculate // the possibly changed neighbors list and acceleration md.Lx = Lx; md.Ly = Ly; md.desiredKE = desiredKE; control.println("desired KE"+desiredKE); md.findNeighbors(); md.computeAcceleration(); display.setPreferredMinMax(0, Lx, 0, Ly); resetData(); } } //reset() establishes the default values for the various inputs read in during initialize() //----------------------------------------------------------------------------------------------------------------------- public void reset() { control.setValue("Number of Particles", 64); control.setAdjustableValue("Lx", 20.0); control.setAdjustableValue("Ly", 20.0); control.setValue("initial kinetic energy per particle", 10.0); control.setValue("CutOff Factor / 2^(1/6)", 1.0); control.setValue("Damping Factor", 100); control.setAdjustableValue("dt", 0.001); control.setValue("Find Neighbor Time", 20); control.setValue("Give Random Kicks?", false); control.setAdjustableValue("Desired KE per particle", 5.0); control.setValue("Silo Set-Up?", false); control.setValue("Aperture Size", 5); control.setValue("Have Close CutOff?", false); control.setValue("Artificial Temperature Reduction?", false); control.setValue("Allow Time Slow Down?", false); enableStepsPerDisplay(true); display.setSquareAspect(true); // so particles will appear as circular disks } //resetData() clears all the drawing frames and current averages----------------------------------------------------------- public void resetData() { md.resetAverages(); GUIUtils.clearDrawingFrameData(false); // clears old data from the plot frames } //main starts the program running by creating the control object and adding the button resetData //------------------------------------------------------------------------------------------------------------------------- public static void main(String[] args) { SimulationControl control = SimulationControl.createApp(new LJParticlesApp()); control.addButton("resetData", "Reset Data"); } } // ends LJParticlesApp