hydro_iact.h

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/*******************************************************************************
 * This file is part of SWIFT.
 * Copyright (c) 2016 Matthieu Schaller (schaller@strw.leidenuniv.nl)
 *
 * 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_MINIMAL_HYDRO_IACT_H
#define SWIFT_MINIMAL_HYDRO_IACT_H
 
#include "adaptive_softening_iact.h"
#include "adiabatic_index.h"
#include "hydro_parameters.h"
//#include "minmax.h"
#include "signal_velocity.h"
 
__attribute__((always_inline)) INLINE static void runner_iact_density(
    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) {
 
  float wi, wj, wi_dx, wj_dx;
 
#ifdef SWIFT_DEBUG_CHECKS
  if (pi->time_bin >= time_bin_inhibited)
    error("Inhibited pi in interaction function!");
  if (pj->time_bin >= time_bin_inhibited)
    error("Inhibited pj in interaction function!");
#endif
 
  /* Get r and 1/r. */
  const float r = sqrtf(r2);
  const float r_inv = r ? 1.0f / r : 0.0f;
 
  /* Get the masses. */
  const float mi = pi->mass;
  const float mj = pj->mass;
 
  /* Compute density of pi. */
  const float hi_inv = 1.f / hi;
  const float ui = r * hi_inv;
  kernel_deval(ui, &wi, &wi_dx);
 
  pi->rho += mj * wi;
  pi->density.rho_dh -= mj * (hydro_dimension * wi + ui * wi_dx);
  pi->density.wcount += wi;
  pi->density.wcount_dh -= (hydro_dimension * wi + ui * wi_dx);
  adaptive_softening_add_correction_term(pi, ui, hi_inv, mj);
 
  /* Compute density of pj. */
  const float hj_inv = 1.f / hj;
  const float uj = r * hj_inv;
  kernel_deval(uj, &wj, &wj_dx);
 
  pj->rho += mi * wj;
  pj->density.rho_dh -= mi * (hydro_dimension * wj + uj * wj_dx);
  pj->density.wcount += wj;
  pj->density.wcount_dh -= (hydro_dimension * wj + uj * wj_dx);
  adaptive_softening_add_correction_term(pj, uj, hj_inv, mi);
 
  /* Compute dv dot r */
  float dv[3], curlvr[3];
 
  const float faci = mj * wi_dx * r_inv;
  const float facj = mi * wj_dx * r_inv;
 
  dv[0] = pi->v[0] - pj->v[0];
  dv[1] = pi->v[1] - pj->v[1];
  dv[2] = pi->v[2] - pj->v[2];
  const float dvdr = dv[0] * dx[0] + dv[1] * dx[1] + dv[2] * dx[2];
 
  pi->density.div_v -= faci * dvdr;
  pj->density.div_v -= facj * dvdr;
 
  /* Compute dv cross r */
  curlvr[0] = dv[1] * dx[2] - dv[2] * dx[1];
  curlvr[1] = dv[2] * dx[0] - dv[0] * dx[2];
  curlvr[2] = dv[0] * dx[1] - dv[1] * dx[0];
 
  pi->density.rot_v[0] += faci * curlvr[0];
  pi->density.rot_v[1] += faci * curlvr[1];
  pi->density.rot_v[2] += faci * curlvr[2];
 
  pj->density.rot_v[0] += facj * curlvr[0];
  pj->density.rot_v[1] += facj * curlvr[1];
  pj->density.rot_v[2] += facj * curlvr[2];
}
 
__attribute__((always_inline)) INLINE static void runner_iact_nonsym_density(
    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) {
 
  float wi, wi_dx;
 
#ifdef SWIFT_DEBUG_CHECKS
  if (pi->time_bin >= time_bin_inhibited)
    error("Inhibited pi in interaction function!");
  if (pj->time_bin >= time_bin_inhibited)
    error("Inhibited pj in interaction function!");
#endif
 
  /* Get the masses. */
  const float mj = pj->mass;
 
  /* Get r and 1/r. */
  const float r = sqrtf(r2);
  const float r_inv = r ? 1.0f / r : 0.0f;
 
  const float h_inv = 1.f / hi;
  const float ui = r * h_inv;
  kernel_deval(ui, &wi, &wi_dx);
 
  pi->rho += mj * wi;
  pi->density.rho_dh -= mj * (hydro_dimension * wi + ui * wi_dx);
  pi->density.wcount += wi;
  pi->density.wcount_dh -= (hydro_dimension * wi + ui * wi_dx);
  adaptive_softening_add_correction_term(pi, ui, h_inv, mj);
 
  /* Compute dv dot r */
  float dv[3], curlvr[3];
 
  const float faci = mj * wi_dx * r_inv;
 
  dv[0] = pi->v[0] - pj->v[0];
  dv[1] = pi->v[1] - pj->v[1];
  dv[2] = pi->v[2] - pj->v[2];
  const float dvdr = dv[0] * dx[0] + dv[1] * dx[1] + dv[2] * dx[2];
 
  pi->density.div_v -= faci * dvdr;
 
  /* Compute dv cross r */
  curlvr[0] = dv[1] * dx[2] - dv[2] * dx[1];
  curlvr[1] = dv[2] * dx[0] - dv[0] * dx[2];
  curlvr[2] = dv[0] * dx[1] - dv[1] * dx[0];
 
  pi->density.rot_v[0] += faci * curlvr[0];
  pi->density.rot_v[1] += faci * curlvr[1];
  pi->density.rot_v[2] += faci * curlvr[2];
}
 
__attribute__((always_inline)) INLINE static void runner_iact_gradient(
    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) {}
 
__attribute__((always_inline)) INLINE static void runner_iact_nonsym_gradient(
    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) {}
 
__attribute__((always_inline)) INLINE static void runner_iact_force(
    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) {
 
#ifdef SWIFT_DEBUG_CHECKS
  if (pi->time_bin >= time_bin_inhibited)
    error("Inhibited pi in interaction function!");
  if (pj->time_bin >= time_bin_inhibited)
    error("Inhibited pj in interaction function!");
#endif
 
  /* Cosmological factors entering the EoMs */
  const float fac_mu = pow_three_gamma_minus_five_over_two(a);
  const float a2_Hubble = a * a * H;
 
  /* Get r and 1/r. */
  const float r = sqrtf(r2);
  const float r_inv = r ? 1.0f / r : 0.0f;
 
  /* Recover some data */
  const float mi = pi->mass;
  const float mj = pj->mass;
  const float rhoi = pi->rho;
  const float rhoj = pj->rho;
  const float pressurei = pi->force.pressure;
  const float pressurej = pj->force.pressure;
 
  /* Get the kernel for hi. */
  const float hi_inv = 1.0f / hi;
  const float hid_inv = pow_dimension_plus_one(hi_inv); /* 1/h^(d+1) */
  const float xi = r * hi_inv;
  float wi, wi_dx;
  kernel_deval(xi, &wi, &wi_dx);
  const float wi_dr = hid_inv * wi_dx;
 
  /* Get the kernel for hj. */
  const float hj_inv = 1.0f / hj;
  const float hjd_inv = pow_dimension_plus_one(hj_inv); /* 1/h^(d+1) */
  const float xj = r * hj_inv;
  float wj, wj_dx;
  kernel_deval(xj, &wj, &wj_dx);
  const float wj_dr = hjd_inv * wj_dx;
 
  /* Variable smoothing length term */
  const float f_ij = 1.f - pi->force.f / mj;
  const float f_ji = 1.f - pj->force.f / mi;
 
  /* Compute gradient terms */
  const float P_over_rho2_i = pressurei / (rhoi * rhoi) * f_ij;
  const float P_over_rho2_j = pressurej / (rhoj * rhoj) * f_ji;
 
  /* Compute dv dot r. */
  const float dvdr = (pi->v[0] - pj->v[0]) * dx[0] +
                     (pi->v[1] - pj->v[1]) * dx[1] +
                     (pi->v[2] - pj->v[2]) * dx[2];
 
  /* Add Hubble flow */
  const float dvdr_Hubble = dvdr + a2_Hubble * r2;
 
  /* Are the particles moving towards each others ? */
  const float omega_ij = MIN(dvdr_Hubble, 0.f);
  const float mu_ij = fac_mu * r_inv * omega_ij; /* This is 0 or negative */
 
  /* Compute signal velocity */
  const float v_sig = signal_velocity(dx, pi, pj, mu_ij, const_viscosity_beta);
 
  /* Grab balsara switches */
  const float balsara_i = pi->force.balsara;
  const float balsara_j = pj->force.balsara;
 
  /* Construct the full viscosity term */
  const float rho_ij = 0.5f * (rhoi + rhoj);
  const float visc = -0.25f * v_sig * (balsara_i + balsara_j) * mu_ij / rho_ij;
 
  /* Convolve with the kernel */
  const float visc_acc_term =
      0.5f * visc * (wi_dr * f_ij + wj_dr * f_ji) * r_inv;
 
  /* SPH acceleration term */
  const float sph_acc_term =
      (P_over_rho2_i * wi_dr + P_over_rho2_j * wj_dr) * r_inv;
 
  /* Adaptive softening acceleration term */
  const float adapt_soft_acc_term =
      adaptive_softening_get_acc_term(pi, pj, wi_dr, wj_dr, f_ij, f_ji, r_inv);
 
  /* Assemble the acceleration */
  const float acc = sph_acc_term + visc_acc_term + adapt_soft_acc_term;
 
  /* Use the force Luke ! */
  pi->a_hydro[0] -= mj * acc * dx[0];
  pi->a_hydro[1] -= mj * acc * dx[1];
  pi->a_hydro[2] -= mj * acc * dx[2];
 
  pj->a_hydro[0] += mi * acc * dx[0];
  pj->a_hydro[1] += mi * acc * dx[1];
  pj->a_hydro[2] += mi * acc * dx[2];
 
  /* Get the time derivative for u. */
  const float sph_du_term_i = P_over_rho2_i * dvdr * r_inv * wi_dr;
  const float sph_du_term_j = P_over_rho2_j * dvdr * r_inv * wj_dr;
 
  /* Viscosity term */
  const float visc_du_term = 0.5f * visc_acc_term * dvdr_Hubble;
 
  /* Assemble the energy equation term */
  const float du_dt_i = sph_du_term_i + visc_du_term;
  const float du_dt_j = sph_du_term_j + visc_du_term;
 
  /* Internal energy time derivatibe */
  pi->u_dt += du_dt_i * mj;
  pj->u_dt += du_dt_j * mi;
 
  /* Get the time derivative for h. */
  pi->force.h_dt -= mj * dvdr * r_inv / rhoj * wi_dr * f_ij;
  pj->force.h_dt -= mi * dvdr * r_inv / rhoi * wj_dr * f_ji;
 
  /* Update the signal velocity. */
  pi->force.v_sig = MAX(pi->force.v_sig, v_sig);
  pj->force.v_sig = MAX(pj->force.v_sig, v_sig);
}
 
__attribute__((always_inline)) INLINE static void runner_iact_nonsym_force(
    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) {
 
#ifdef SWIFT_DEBUG_CHECKS
  if (pi->time_bin >= time_bin_inhibited)
    error("Inhibited pi in interaction function!");
  if (pj->time_bin >= time_bin_inhibited)
    error("Inhibited pj in interaction function!");
#endif
 
  /* Cosmological factors entering the EoMs */
  const float fac_mu = pow_three_gamma_minus_five_over_two(a);
  const float a2_Hubble = a * a * H;
 
  /* Get r and 1/r. */
  const float r = sqrtf(r2);
  const float r_inv = r ? 1.0f / r : 0.0f;
 
  /* Recover some data */
  const float mi = pi->mass;
  const float mj = pj->mass;
  const float rhoi = pi->rho;
  const float rhoj = pj->rho;
  const float pressurei = pi->force.pressure;
  const float pressurej = pj->force.pressure;
 
  /* Get the kernel for hi. */
  const float hi_inv = 1.0f / hi;
  const float hid_inv = pow_dimension_plus_one(hi_inv); /* 1/h^(d+1) */
  const float xi = r * hi_inv;
  float wi, wi_dx;
  kernel_deval(xi, &wi, &wi_dx);
  const float wi_dr = hid_inv * wi_dx;
 
  /* Get the kernel for hj. */
  const float hj_inv = 1.0f / hj;
  const float hjd_inv = pow_dimension_plus_one(hj_inv); /* 1/h^(d+1) */
  const float xj = r * hj_inv;
  float wj, wj_dx;
  kernel_deval(xj, &wj, &wj_dx);
  const float wj_dr = hjd_inv * wj_dx;
 
  /* Variable smoothing length term */
  const float f_ij = 1.f - pi->force.f / mj;
  const float f_ji = 1.f - pj->force.f / mi;
 
  /* Compute gradient terms */
  const float P_over_rho2_i = pressurei / (rhoi * rhoi) * f_ij;
  const float P_over_rho2_j = pressurej / (rhoj * rhoj) * f_ji;
 
  /* Compute dv dot r. */
  const float dvdr = (pi->v[0] - pj->v[0]) * dx[0] +
                     (pi->v[1] - pj->v[1]) * dx[1] +
                     (pi->v[2] - pj->v[2]) * dx[2];
 
  /* Add Hubble flow */
  const float dvdr_Hubble = dvdr + a2_Hubble * r2;
 
  /* Are the particles moving towards each others ? */
  const float omega_ij = MIN(dvdr_Hubble, 0.f);
  const float mu_ij = fac_mu * r_inv * omega_ij; /* This is 0 or negative */
 
  /* Compute signal velocity */
  const float v_sig = signal_velocity(dx, pi, pj, mu_ij, const_viscosity_beta);
 
  /* Grab balsara switches */
  const float balsara_i = pi->force.balsara;
  const float balsara_j = pj->force.balsara;
 
  /* Construct the full viscosity term */
  const float rho_ij = 0.5f * (rhoi + rhoj);
  const float visc = -0.25f * v_sig * (balsara_i + balsara_j) * mu_ij / rho_ij;
 
  /* Convolve with the kernel */
  const float visc_acc_term =
      0.5f * visc * (wi_dr * f_ij + wj_dr * f_ji) * r_inv;
 
  /* SPH acceleration term */
  const float sph_acc_term =
      (P_over_rho2_i * wi_dr + P_over_rho2_j * wj_dr) * r_inv;
 
  /* Adaptive softening acceleration term */
  const float adapt_soft_acc_term =
      adaptive_softening_get_acc_term(pi, pj, wi_dr, wj_dr, f_ij, f_ji, r_inv);
 
  /* Assemble the acceleration */
  const float acc = sph_acc_term + visc_acc_term + adapt_soft_acc_term;
 
  /* Use the force Luke ! */
  pi->a_hydro[0] -= mj * acc * dx[0];
  pi->a_hydro[1] -= mj * acc * dx[1];
  pi->a_hydro[2] -= mj * acc * dx[2];
 
  /* Get the time derivative for u. */
  const float sph_du_term_i = P_over_rho2_i * dvdr * r_inv * wi_dr;
 
  /* Viscosity term */
  const float visc_du_term = 0.5f * visc_acc_term * dvdr_Hubble;
 
  /* Assemble the energy equation term */
  const float du_dt_i = sph_du_term_i + visc_du_term;
 
  /* Internal energy time derivatibe */
  pi->u_dt += du_dt_i * mj;
 
  /* Get the time derivative for h. */
  pi->force.h_dt -= mj * dvdr * r_inv / rhoj * wi_dr * f_ij;
 
  /* Update the signal velocity. */
  pi->force.v_sig = MAX(pi->force.v_sig, v_sig);
}
 
#endif /* SWIFT_MINIMAL_HYDRO_IACT_H */