Basilisk source code (http://basilisk.fr/src/)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
 /**
# An advection solver
We wish to solve the advection equations
$$
\partial_tf_i+\mathbf{u}\cdot\nabla f_i=0
$$
where $\mathbf{u}$ is the velocity field and $f_i$ are a list of
passive tracers. This can be done with a fluxbased advection scheme
such as the 2ndorder, unsplit, upwind scheme of [BellCollelaGlaz,
1989](references.bib#bell89).
The main time loop is defined in [run.h](). A stable timestep needs to
respect the [CFL
condition](http://en.wikipedia.org/wiki/Courant%E2%80%93Friedrichs%E2%80%93Lewy_condition). */
#include "run.h"
#include "timestep.h"
/**
We allocate the (face) velocity field. For compatibility with the
other solvers, we allocate it as `uf` and define an alias. The
`gradient` function is used to set the type of slopelimiting
required. The default is to not use any limiting (i.e. a purely
centered slope estimation). */
face vector uf[];
#define u uf
double (* gradient) (double, double, double) = NULL;
/**
Here we set the gradient functions for each tracer (as defined in the
userprovided `tracers` list). */
extern scalar * tracers;
event defaults (i = 0) {
for (scalar f in tracers)
f.gradient = gradient;
}
/**
We apply boundary conditions after user initialisation. */
event init (i = 0) {
boundary ((scalar *){u});
boundary (tracers);
}
/**
The timestep is set using the velocity field and the CFL
criterion. The integration itself is performed in the events of
[tracer.h](). */
event velocity (i++,last) {
dt = dtnext (timestep (u, DT));
}
#include "tracer.h"
