public void compute_line_normal(int nstart, int n)
{
int p1, p2;
double[] z = new double[3], delta = new double[3], norm = new double[3];
z[0] = 0.0; z[1] = 0.0; z[2] = 1.0;
int m = nstart;
for (int i = 0; i < n; i++)
{
p1 = lines[m].p1;
p2 = lines[m].p2;
MathExtra.sub3(pts[p2].x, pts[p1].x, delta);
MathExtra.cross3(z, delta, norm);
MathExtra.norm3(norm);
norm[2] = 0.0;
Line line = lines[m];
line.norm = new double[3];
line.norm[0] = norm[0];
line.norm[1] = norm[1];
line.norm[2] = norm[2];
lines[m] = line;
m++;
}
}
public void compute_tri_normal(int nstart, int n)
{
int p1, p2, p3;
double[] delta12 = new double[3], delta13 = new double[3];
int m = nstart;
for (int i = 0; i < n; i++)
{
p1 = tris[m].p1;
p2 = tris[m].p2;
p3 = tris[m].p3;
MathExtra.sub3(pts[p2].x, pts[p1].x, delta12);
MathExtra.sub3(pts[p3].x, pts[p1].x, delta13);
MathExtra.cross3(delta12, delta13, tris[m].norm);
MathExtra.norm3(tris[m].norm);
m++;
}
}
protected RanPark random; // RNG for particle reflection
void diffuse(Particle.OnePart p, double[] norm)
{
// specular reflection
// reflect incident v around norm
if (random.uniform() > acc)
{
MathExtra.reflect3(p.v, norm);
// diffuse reflection
// vrm = most probable speed of species, eqns (4.1) and (4.7)
// vperp = velocity component perpendicular to surface along norm, eqn (12.3)
// vtan12 = 2 velocity components tangential to surface
// tangent1 = component of particle v tangential to surface,
// check if tangent1 = 0 (normal collision), set randomly
// tangent2 = norm x tangent1 = orthogonal tangential direction
// tangent12 are both unit vectors
}
else
{
double[] tangent1 = new double[3], tangent2 = new double[3];
List <Particle.Species> species = sparta.particle.species;
int ispecies = p.ispecies;
double vrm = Math.Sqrt(2.0 * sparta.update.boltz * twall / species[ispecies].mass);
double vperp = vrm * Math.Sqrt(-Math.Log(random.uniform()));
double theta = MyConst.MY_2PI * random.uniform();
double vtangent = vrm * Math.Sqrt(-Math.Log(random.uniform()));
double vtan1 = vtangent * Math.Sin(theta);
double vtan2 = vtangent * Math.Cos(theta);
double[] v = p.v;
double dot = MathExtra.dot3(v, norm);
double beta_un, normalized_distbn_fn;
tangent1[0] = v[0] - dot * norm[0];
tangent1[1] = v[1] - dot * norm[1];
tangent1[2] = v[2] - dot * norm[2];
if (MathExtra.lensq3(tangent1) == 0.0)
{
tangent2[0] = random.uniform();
tangent2[1] = random.uniform();
tangent2[2] = random.uniform();
MathExtra.cross3(norm, tangent2, tangent1);
}
MathExtra.norm3(tangent1);
MathExtra.cross3(norm, tangent1, tangent2);
// add in translation or rotation vector if specified
// only keep portion of vector tangential to surface element
if (trflag != 0)
{
double vxdelta, vydelta, vzdelta;
if (tflag != 0)
{
vxdelta = vx; vydelta = vy; vzdelta = vz;
double adot = vxdelta * norm[0] + vydelta * norm[1] + vzdelta * norm[2];
if (Math.Abs(adot) > 0.001)
{
adot /= vrm;
do
{
do
{
beta_un = (6.0 * random.uniform() - 3.0);
} while (beta_un + adot < 0.0);
normalized_distbn_fn = 2.0 * (beta_un + adot) /
(adot + Math.Sqrt(adot * adot + 2.0)) *
Math.Exp(0.5 + (0.5 * adot) * (adot - Math.Sqrt(adot * adot + 2.0)) -
beta_un * beta_un);
} while (normalized_distbn_fn < random.uniform());
vperp = beta_un * vrm;
}
}
else
{
double[] x = p.x;
vxdelta = wy * (x[2] - pz) - wz * (x[1] - py);
vydelta = wz * (x[0] - px) - wx * (x[2] - pz);
vzdelta = wx * (x[1] - py) - wy * (x[0] - px);
double adot = vxdelta * norm[0] + vydelta * norm[1] + vzdelta * norm[2];
vxdelta -= adot * norm[0];
vydelta -= adot * norm[1];
vzdelta -= adot * norm[2];
}
v[0] = vperp * norm[0] + vtan1 * tangent1[0] + vtan2 * tangent2[0] + vxdelta;
v[1] = vperp * norm[1] + vtan1 * tangent1[1] + vtan2 * tangent2[1] + vydelta;
v[2] = vperp * norm[2] + vtan1 * tangent1[2] + vtan2 * tangent2[2] + vzdelta;
// no translation or rotation
}
else
{
v[0] = vperp * norm[0] + vtan1 * tangent1[0] + vtan2 * tangent2[0];
v[1] = vperp * norm[1] + vtan1 * tangent1[1] + vtan2 * tangent2[1];
v[2] = vperp * norm[2] + vtan1 * tangent1[2] + vtan2 * tangent2[2];
}
p.erot = sparta.particle.erot(ispecies, twall, random);
p.evib = sparta.particle.evib(ispecies, twall, random);
}
}