inject_particles.c

Continuously injecting and removing new particles.

Continuously injecting and removing new particles.

The confetti.c example shows how particles can be added by creating new lists. Here we show how particles can be added to an existing lists.

Particles and their pid()

set grid 
set size ratio -1
set xlabel 'x'
set ylabel 'y'
plot 'out' u 1:2:3 with points pt 4 palette t 'Residence time'

Snapshot of particles and their spend in the domain (script)

reset
set xr [0:100]
set xlabel 't'
plot 'log' u 1:2 t 'Particles', '' u 1:3 t 'Allocated space'

Particles and allocated space on pid 0 (script)

#include "navier-stokes/centered.h"
#include "tracer-particles.h"
#include "view.h"
#include "scatter2.h"

u.n[left] = dirichlet (fabs(y) < 0.5);
u.t[left] = (fabs(y) < 0.5 ? dirichlet (0.3*sin(t)) : neumann (0));
p[left] = neumann (0);

u.n[right] = neumann (0);
p[right] = dirichlet (0);

Particles trackers;

int main() {
  L0 = 10;
  Y0 = X0 = -L0/2.;
  run();
}

event init (t = 0) {
  trackers = new_tracer_particles (0);
}

event adder (t = 1; t += 0.1) {
  for (double yp = -0.5 ; yp <= 0.5; yp += 0.1) {
    particle p = {.x = X0, .y = yp, .z = 0, .tag = t*10};
    set_a_particle_attributes (&p);
    add_particle (p, trackers);
  }
}

event remover (i++) {
  remove_particles (trackers, x > 3.2);
}

event damp (i++) {
  foreach()
    if (x > 3)
      u.y[] -= u.y[] * dt*(1. - exp(-(x - 3)))/2.;
  boundary ({u.y});
}

event adapt (i++) {
  adapt_wavelet ((scalar*){u}, (double[]){0.025, 0.025}, 7);
}

event trace_p (t += 0.1) {
  if (pid() == 0)
    fprintf (stderr, "%g %ld %ld\n", t, pn[trackers], pna[trackers]);
}

event mov (t += 0.5) {
  scatter (trackers, pc = {sin(pid()), cos(pid()), sin(2.5*pid())});
  box();
  save ("parts.mp4");
}

event stop (t = 100) {
  for (int i = 0; i < npe(); i++) {
    foreach_particle_in(trackers) {
      if (i == pid())
	printf ("%g %g %g\n", x, y, (t - p().tag/10));
    }
#if _MPI
    MPI_Barrier(MPI_COMM_WORLD);
#endif
  }
}