src/examples/turbulence.c

Decaying two-dimensional turbulence

We solve the two-dimensional incompressible Euler equations using a vorticity–streamfunction formulation.

#include "grid/multigrid.h"
#include "navier-stokes/stream.h"

The domain is square of size unity by default. The resolution is constant at 256^2.

int main() {
  init_grid (256);
  run();
}

The initial condition for vorticity is just a white noise in the range [-1:1] .

event init (i = 0) {
  double a = 1. [0,-1];
  foreach()
    omega[] = a*noise();
}

We generate images of the vorticity field every 4 timesteps up to t=1000. We fix the colorscale to [-0.3:0.3].

event output (i += 4; t <= 1000) {
  output_ppm (omega, min = -0.3, max = 0.3, file = "omega.mp4");
}