/***********************************************************************************
* Miscellaneous Functions
***********************************************************************************/
double install_test(void){
struct reb_simulation* sim = reb_create_simulation();
struct reb_particle p = {0};
p.m = 1.;
reb_add(sim, p);
struct reb_particle p1 = reb_tools_orbit2d_to_particle(sim->G, p, 0., 1., 0.2, 0., 0.);
reb_add(sim, p1);
reb_integrate(sim, 1.);
return sim->particles[1].x;
}
int main(int argc, char* argv[]){
struct reb_simulation* sim = reb_create_simulation();
struct reb_particle p = {0};
p.m = 1.;
reb_add(sim, p);
double m = 0.;
double a1 = 1.;
double a2 = 2.;
double e = 0.4;
double omega = 0.;
double f = 0.;
struct reb_particle p1 = reb_tools_orbit2d_to_particle(sim->G, p, m, a1, e, omega, f);
struct reb_particle p2 = reb_tools_orbit2d_to_particle(sim->G, p, m, a2, e, omega, f);
reb_add(sim,p1);
reb_add(sim,p2);
reb_move_to_com(sim);
struct rebx_extras* rebx = rebx_init(sim); // first initialize rebx
/* We now add our custom post_timestep_modification
* We pass rebx, a name, and the function that should be called.
* For a custom force, we also have to pass force_is_velocity_dependent,
* which should be 1 if our function uses particle velocities, and 0 otherwise.
*/
struct rebx_effect* effect = rebx_add_custom_post_timestep_modification(rebx, "simple_drag", simple_drag);
//struct rebx_effect* effect = rebx_add_custom_force(rebx, "stark_force", stark_force, 0);
double* c = rebx_add_param(effect, "c", REBX_TYPE_DOUBLE);
*c = 1.e-5; // we wrote both our functions to read a parameter c, so we set it.
double tmax = 5.e4;
reb_integrate(sim, tmax);
rebx_free(rebx); // Free all the memory allocated by rebx
}
int main(int argc, char* argv[]){
struct reb_simulation* sim = reb_create_simulation();
// Setup constants
sim->integrator = REB_INTEGRATOR_IAS15;
sim->G = 6.674e-11; // Use SI units
sim->dt = 1e4; // Initial timestep in sec
sim->N_active = 2; // Only the sun and the planet affect other particles gravitationally
sim->heartbeat = heartbeat;
sim->usleep = 1000; // Slow down integration (for visualization only)
// sun
struct reb_particle sun = {0};
sun.m = 1.99e30; // mass of Sun in kg
reb_add(sim, sun);
struct rebx_extras* rebx = rebx_init(sim);
struct rebx_effect* rad_params = rebx_add(rebx, "radiation_forces");
double* c = rebx_add_param(rad_params, "c", REBX_TYPE_DOUBLE);
*c = 3.e8; // speed of light in SI units
// Will assume particles[0] is the radiation source by default. You can also add a flag to a particle explicitly
int* source = rebx_add_param(&sim->particles[0], "radiation_source", REBX_TYPE_INT);
// Saturn (simulation set up in Saturn's orbital plane, i.e., inc=0, so only need 4 orbital elements
double mass_sat = 5.68e26; // Mass of Saturn
double a_sat = 1.43e12; // Semimajor axis of Saturn in m
double e_sat = 0.056; // Eccentricity of Saturn
double pomega_sat = 0.; // Angle from x axis to pericenter
double f_sat = 0.; // True anomaly of Saturn
struct reb_particle saturn = reb_tools_orbit2d_to_particle(sim->G, sun, mass_sat, a_sat, e_sat, pomega_sat, f_sat);
reb_add(sim, saturn);
/* Dust particles
Here we imagine particles launched from Saturn's irregular Satellite Phoebe.
Such grains will inherit the moon's orbital elements (e.g. Tamayo et al. 2011)
In order for a particle to feel radiation forces, we have to set their beta parameter,
the ratio of the radiation pressure force to the gravitional force from the star (Burns et al. 1979).
We do this in two ways below.*/
double a_dust = 1.30e10; // semimajor axis of satellite Phoebe, in m
double e_dust = 0.16; // eccentricity of Phoebe
double inc_dust = 175.*M_PI/180.; // inclination of Phoebe to Saturn's orbital plane
double Omega_dust = 0.; // longitude of ascending node
double omega_dust = 0.; // argument of pericenter
double f_dust = 0.; // true anomaly
// We first set up the orbit and add the particles
double m_dust = 0.; // treat dust particles as massless
struct reb_particle p = reb_tools_orbit_to_particle(sim->G, sim->particles[1], m_dust, a_dust, e_dust, inc_dust, Omega_dust, omega_dust, f_dust);
reb_add(sim, p);
// For the first particle we simply specify beta directly.
double* beta = rebx_add_param(&sim->particles[2], "beta", REBX_TYPE_DOUBLE);
*beta = 0.1;
// We now add a 2nd particle on the same orbit, but set its beta using physical parameters.
struct reb_particle p2 = reb_tools_orbit_to_particle(sim->G, sim->particles[1], 0., a_dust, e_dust, inc_dust, Omega_dust, omega_dust, f_dust);
reb_add(sim, p2);
/* REBOUNDx has a convenience function to calculate beta given the gravitational constant G, the star's luminosity and mass, and the grain's physical radius, density and radiation pressure coefficient Q_pr (Burns et al. 1979). */
// Particle parameters
double radius = 1.e-5; // in meters
double density = 1.e3; // kg/m3 = 1g/cc
double Q_pr = 1.; // Equals 1 in limit where particle radius >> wavelength of radiation
double L = 3.85e26; // Luminosity of the sun in Watts
beta = rebx_add_param(&sim->particles[3], "beta", REBX_TYPE_DOUBLE);
*beta = rebx_rad_calc_beta(sim->G, *c, sim->particles[0].m, L, radius, density, Q_pr);
printf("Particle 2 has beta = %f\n", *beta);
reb_move_to_com(sim);
printf("Time\t\tEcc (p)\t\tEcc (p2)\n");
reb_integrate(sim, tmax);
rebx_free(rebx); /* free memory allocated by REBOUNDx */
}
