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Matthieu Schaller authoredMatthieu Schaller authored
sink_iact.h 13.23 KiB
/*******************************************************************************
* This file is part of SWIFT.
* Copyright (c) 2021 Loic Hausammann (loic.hausammann@epfl.ch)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
******************************************************************************/
#ifndef SWIFT_GEAR_SINKS_IACT_H
#define SWIFT_GEAR_SINKS_IACT_H
/* Local includes */
#include "gravity.h"
#include "gravity_iact.h"
#include "sink_properties.h"
/**
* @brief do sink computation after the runner_iact_density (symmetric
* version)
*
* Note: This functions breaks MPI.
*
* @param r2 Comoving square distance between the two particles.
* @param dx Comoving vector separating both particles (pi - pj).
* @param hi Comoving smoothing-length of particle i.
* @param hj Comoving smoothing-length of particle j.
* @param pi First particle.
* @param pj Second particle.
* @param a Current scale factor.
* @param H Current Hubble parameter.
*/
__attribute__((always_inline)) INLINE static void runner_iact_sink(
const float r2, const float dx[3], const float hi, const float hj,
struct part *restrict pi, struct part *restrict pj, const float a,
const float H, const float cut_off_radius) {
/* In order to prevent the formation of two sink particles at a distance
* smaller than the sink cutoff radius, we keep only gas particles with
* the smallest potential. */
const float r = sqrtf(r2);
/* if the distance is less than the cut off radius */
if (r < cut_off_radius) {
/*
* NOTE: Those lines break MPI
*/
float potential_i = pi->gpart->potential;
float potential_j = pj->gpart->potential;
/* prevent the particle with the largest potential to form a sink */
if (potential_i > potential_j) {
pi->sink_data.can_form_sink = 0;
return;
}
if (potential_j > potential_i) {
pj->sink_data.can_form_sink = 0;
return; }
}
}
/**
* @brief do sink computation after the runner_iact_density (non symmetric
* version)
*
* @param r2 Comoving square distance between the two particles.
* @param dx Comoving vector separating both particles (pi - pj).
* @param hi Comoving smoothing-length of particle i.
* @param hj Comoving smoothing-length of particle j.
* @param pi First particle.
* @param pj Second particle (not updated).
* @param a Current scale factor.
* @param H Current Hubble parameter.
*/
__attribute__((always_inline)) INLINE static void runner_iact_nonsym_sink(
const float r2, const float dx[3], const float hi, const float hj,
struct part *restrict pi, const struct part *restrict pj, const float a,
const float H, const float cut_off_radius) {
/* In order to prevent the formation of two sink particles at a distance
* smaller than the sink cutoff radius, we keep only gas particles with
* the smallest potential. */
const float r = sqrtf(r2);
if (r < cut_off_radius) {
float potential_i = pi->gpart->potential;
float potential_j = pj->gpart->potential;
/* if the potential is larger
* prevent the particle to form a sink */
if (potential_i > potential_j) pi->sink_data.can_form_sink = 0;
}
}
/**
* @brief Compute sink-sink swallow interaction (non-symmetric).
*
* Note: Energies are computed with physical quantities, not the comoving ones.
*
* @param r2 Comoving square distance between the two particles.
* @param dx Comoving vector separating both particles (pi - pj).
* @param ri Comoving cut off radius of particle i.
* @param rj Comoving cut off radius of particle j.
* @param si First sink particle.
* @param sj Second sink particle.
*/
__attribute__((always_inline)) INLINE static void
runner_iact_nonsym_sinks_sink_swallow(const float r2, const float dx[3],
const float ri, const float rj,
struct sink *restrict si,
struct sink *restrict sj,
const int with_cosmology,
const struct cosmology *cosmo,
const struct gravity_props *grav_props) {
/* Relative velocity between th sinks */
const float dv[3] = {sj->v[0] - si->v[0], sj->v[1] - si->v[1],
sj->v[2] - si->v[2]};
const float a = cosmo->a;
const float H = cosmo->H;
const float a2H = a * a * H;
/* Calculate the velocity with the Hubble flow */
const float v_plus_H_flow[3] = {a2H * dx[0] + dv[0], a2H * dx[1] + dv[1], a2H * dx[2] + dv[2]};
/* Binding energy check */
/* Compute the physical relative velocity between the particles */
const float dv_physical[3] = {v_plus_H_flow[0] * cosmo->a_inv,
v_plus_H_flow[1] * cosmo->a_inv,
v_plus_H_flow[2] * cosmo->a_inv};
const float dv_physical_squared = dv_physical[0] * dv_physical[0] +
dv_physical[1] * dv_physical[1] +
dv_physical[2] * dv_physical[2];
/* Kinetic energy of the gas */
const float E_kin_rel = 0.5f * dv_physical_squared;
/* Compute the Newtonian or truncated potential the sink exherts onto the
gas particle */
const float eps = gravity_get_softening(si->gpart, grav_props);
const float eps2 = eps * eps;
const float eps_inv = 1.f / eps;
const float eps_inv3 = eps_inv * eps_inv * eps_inv;
const float si_mass = si->mass;
const float sj_mass = sj->mass;
float dummy, pot_ij, pot_ji;
runner_iact_grav_pp_full(r2, eps2, eps_inv, eps_inv3, si_mass, &dummy,
&pot_ij);
runner_iact_grav_pp_full(r2, eps2, eps_inv, eps_inv3, sj_mass, &dummy,
&pot_ji);
/* Compute the physical potential energies :
E_pot_phys = G*pot_grav*a^(-1) + c(z). */
/* The normalization is c(z) = 0 for all redshift z. */
const float E_pot_ij = grav_props->G_Newton * pot_ij * cosmo->a_inv;
const float E_pot_ji = grav_props->G_Newton * pot_ji * cosmo->a_inv;
/* Mechanical energy of the pair i-j and j-i */
const float E_mec_si = E_kin_rel + E_pot_ij;
const float E_mec_sj = E_kin_rel + E_pot_ji;
/* Now, check if one is bound to the other */
if ((E_mec_si > 0) && (E_mec_sj > 0)) {
return;
}
/* The sink with the smaller mass will be merged onto the one with the
* larger mass.
* To avoid rounding issues, we additionally check for IDs if the sink
* have the exact same mass. */
if ((sj->mass < si->mass) || (sj->mass == si->mass && sj->id < si->id)) {
/* This particle is swallowed by the sink with the largest mass of all the
* candidates wanting to swallow it (we use IDs to break ties)*/
if ((sj->merger_data.swallow_mass < si->mass) ||
(sj->merger_data.swallow_mass == si->mass &&
sj->merger_data.swallow_id < si->id)) {
sj->merger_data.swallow_id = si->id;
sj->merger_data.swallow_mass = si->mass;
}
}
#ifdef DEBUG_INTERACTIONS_SINKS
/* Update ngb counters */
if (si->num_ngb_formation < MAX_NUM_OF_NEIGHBOURS_SINKS)
si->ids_ngbs_formation[si->num_ngb_formation] = pj->id;
/* Update ngb counters */
++si->num_ngb_formation;
#endif
}
/**
* @brief Compute sink-gas swallow interaction (non-symmetric).
*
* Note: Energies are computed with physical quantities, not the comoving ones.
*
* @param r2 Comoving square distance between the two particles.
* @param dx Comoving vector separating both particles (pi - pj).
* @param ri Comoving cut off radius of particle i.
* @param hj Comoving smoothing-length of particle j.
* @param si First sink particle.
* @param pj Second particle.
*/
__attribute__((always_inline)) INLINE static void
runner_iact_nonsym_sinks_gas_swallow(const float r2, const float dx[3],
const float ri, const float hj,
struct sink *restrict si,
struct part *restrict pj,
const int with_cosmology,
const struct cosmology *cosmo,
const struct gravity_props *grav_props,
const struct sink_props *sink_properties) {
const float r = sqrtf(r2);
const float f_acc_r_acc = sink_properties->f_acc * ri;
/* If the gas falls within f_acc*r_acc, it is accreted without further check
*/
if (r < f_acc_r_acc) {
/* Check if a gas particle has not been already marked to be swallowed by
another sink particle. */
if (pj->sink_data.swallow_id < si->id) {
pj->sink_data.swallow_id = si->id;
}
/* f_acc*r_acc <= r <= r_acc, we perform other checks */
} else if ((r >= f_acc_r_acc) && (r < ri)) {
/* Relative velocity between th sinks */
const float dv[3] = {pj->v[0] - si->v[0], pj->v[1] - si->v[1],
pj->v[2] - si->v[2]};
const float a = cosmo->a;
const float H = cosmo->H;
const float a2H = a * a * H;
/* Calculate the velocity with the Hubble flow */
const float v_plus_H_flow[3] = {a2H * dx[0] + dv[0], a2H * dx[1] + dv[1],
a2H * dx[2] + dv[2]};
/* Compute the physical relative velocity between the particles */
const float dv_physical[3] = {v_plus_H_flow[0] * cosmo->a_inv,
v_plus_H_flow[1] * cosmo->a_inv,
v_plus_H_flow[2] * cosmo->a_inv};
const float dv_physical_squared = dv_physical[0] * dv_physical[0] +
dv_physical[1] * dv_physical[1] +
dv_physical[2] * dv_physical[2];
/* Compute the physical distance between the particles */
const float dx_physical[3] = {dx[0] * cosmo->a, dx[1] * cosmo->a,
dx[2] * cosmo->a};
const float r_physical = r * cosmo->a;
/* Momentum check */
/* Relative momentum of the gas */
const float specific_angular_momentum_gas[3] = {
dx_physical[1] * dv_physical[2] - dx_physical[2] * dv_physical[1],
dx_physical[2] * dv_physical[0] - dx_physical[0] * dv_physical[2],
dx_physical[0] * dv_physical[1] - dx_physical[1] * dv_physical[0]};
const float L2_gas = specific_angular_momentum_gas[0] * specific_angular_momentum_gas[0] +
specific_angular_momentum_gas[1] * specific_angular_momentum_gas[1] +
specific_angular_momentum_gas[2] * specific_angular_momentum_gas[2];
/* Keplerian angular speed squared */
const float omega_acc_2 = grav_props->G_Newton * si->mass /
(r_physical * r_physical * r_physical);
/*Keplerian angular momentum squared */
const float L2_acc =
(si->r_cut * si->r_cut * si->r_cut * si->r_cut) * omega_acc_2;
/* To be accreted, the gas momentum shoulb lower than the keplerian orbit
* momentum. */
if (L2_gas > L2_acc) {
return;
}
/* Energy check */
/* Kinetic energy of the gas */
float E_kin_relative_gas = 0.5f * dv_physical_squared;
/* Compute the Newtonian or truncated potential the sink exherts onto the
gas particle */
const float eps = gravity_get_softening(si->gpart, grav_props);
const float eps2 = eps * eps;
const float eps_inv = 1.f / eps;
const float eps_inv3 = eps_inv * eps_inv * eps_inv;
const float sink_mass = si->mass;
float dummy, pot_ij;
runner_iact_grav_pp_full(r2, eps2, eps_inv, eps_inv3, sink_mass, &dummy,
&pot_ij);
/* Compute the potential energy that the sink exerts in the gas (do not
forget to convert to physical quantity)*/
/* Compute the potential energy :
E_pot_phys = G*pot_grav*a^(-1) + c(z). */
/* The normalization is c(z) = 0 for all redshift z. */
float E_pot_gas = grav_props->G_Newton * pot_ij * cosmo->a_inv;
/* Mechanical energy of the pair sink-gas */
float E_mec_sink_part = E_kin_relative_gas + E_pot_gas;
/* To be accreted, the gas must be gravitationally bound to the sink. */
if (E_mec_sink_part >= 0) return;
/* Most bound pair check */
/* The pair gas-sink must be the most bound among all sinks */
if (E_mec_sink_part >= pj->sink_data.E_mec_bound) {
return;
}
/* Since this pair gas-sink is the most bounf, keep track of the
E_mec_bound and set the swallow_id accordingly */
pj->sink_data.E_mec_bound = E_mec_sink_part;
pj->sink_data.swallow_id = si->id;
}
#ifdef DEBUG_INTERACTIONS_SINKS
/* Update ngb counters */
if (si->num_ngb_formation < MAX_NUM_OF_NEIGHBOURS_SINKS)
si->ids_ngbs_formation[si->num_ngb_formation] = pj->id;
/* Update ngb counters */
++si->num_ngb_formation;
#endif
}
#endif