initSimulation.py 文件源码

def initVelocities(velocities):             
    # Generate total velocity
    speed = stats.maxwell.rvs(loc=0,scale=config.a,size=config.nParticles)          

    # Generate a random direction  
    phi = np.random.uniform(0, np.pi*2, config.nParticles)
    costheta = np.random.uniform(-1, 1, config.nParticles)
    theta = np.arccos( costheta )

    # Initalize the velocity vectors    
    velocities[:,0] = speed * np.sin( theta ) * np.cos( phi )
    velocities[:,1] = speed * np.sin( theta ) * np.sin( phi )
    velocities[:,2] = speed * np.cos( theta )

    # Set center of mass velocity to zero
    velocities -= np.mean(velocities,axis=0);