src/tracer.h

    Tracer advection event

    This event integrates advection equations of the form \displaystyle \partial_tf_i+\mathbf{u_f}\cdot\nabla f_i=0 where \mathbf{u_f} is the velocity field and f_i are a list of passive tracers.

    The tracers list is defined elsewhere (typically by the user), the face vector field uf and the timestep dt are defined by a solver.

    extern scalar * tracers;
extern face vector uf;
extern double dt;

    On adaptive meshes, tracers need to use linear interpolation (rather than the default bilinear interpolation) to ensure conservation when refining cells.

    #if TREE
event defaults (i = 0) {
  for (scalar s in tracers) {
#if EMBED
    s.refine = s.prolongation = refine_embed_linear;
#else
    s.refine  = refine_linear;
#endif
    s.restriction = restriction_volume_average;
    s.dirty = true; // boundary conditions need to be updated
  }
}
#endif

    The integration is performed using the Bell-Collela-Glaz scheme.

    #include "bcg.h"

event tracer_advection (i++,last) {
  advection (tracers, uf, dt);
}

    Diffusion can be added by overloading this hook.

    event tracer_diffusion (i++,last);

    Usage

    Examples

    Tests