Created all the files for the Pressure-Entropy SPH routines.

src/const.h

@@ -60,7 +60,8 @@
 
 /* SPH variant to use */
 //#define MINIMAL_SPH
-#define GADGET2_SPH
+//#define GADGET2_SPH
+#define HOPKINS_PE_SPH
 //#define DEFAULT_SPH
 
 /* Self gravity stuff. */

src/debug.c

@@ -41,6 +41,8 @@
 #include "./hydro/Minimal/hydro_debug.h"
 #elif defined(GADGET2_SPH)
 #include "./hydro/Gadget2/hydro_debug.h"
+#elif defined(HOPKINS_PE_SPH)
+#include "./hydro/PressureEntropy/hydro_debug.h"
 #elif defined(DEFAULT_SPH)
 #include "./hydro/Default/hydro_debug.h"
 #else

src/hydro.h

@@ -34,6 +34,10 @@
 #include "./hydro/Gadget2/hydro.h"
 #include "./hydro/Gadget2/hydro_iact.h"
 #define SPH_IMPLEMENTATION "Gadget-2 version of SPH (Springel 2005)"
+#elif defined(HOPKINS_PE_SPH)
+#include "./hydro/PressureEntropy/hydro.h"
+#include "./hydro/PressureEntropy/hydro_iact.h"
+#define SPH_IMPLEMENTATION "Pressure-Entropy formulation of SPH (Hopkins 2013)"
 #elif defined(DEFAULT_SPH)
 #include "./hydro/Default/hydro.h"
 #include "./hydro/Default/hydro_iact.h"

src/hydro/PressureEntropy/hydro.h

+/*******************************************************************************
+ * This file is part of SWIFT.
+ * Copyright (c) 2016 Matthieu Schaller (matthieu.schaller@durham.ac.uk)
+ *
+ * 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_PRESSURE_ENTROPY_HYDRO_H
+#define SWIFT_PRESSURE_ENTROPY_HYDRO_H
+
+/**
+ * @file PressureEntropy/hydro_part.h
+ * @brief Pressure-Entropy implementation of SPH (Particle definition)
+ *
+ * The thermal variable is the entropy (S) and the entropy is smoothed over
+ * contact discontinuities to prevent spurious surface tension.
+ *
+ * Follows Hopkins, P., MNRAS, 2013, Volume 428, Issue 4, pp. 2840-2856
+ */
+
+#include "adiabatic_index.h"
+#include "dimension.h"
+#include "equation_of_state.h"
+#include "hydro_properties.h"
+#include "kernel_hydro.h"
+
+/**
+ * @brief Returns the internal energy of a particle
+ *
+ * @param p The particle of interest
+ * @param dt Time since the last kick
+ */
+__attribute__((always_inline)) INLINE static float hydro_get_internal_energy(
+    const struct part *restrict p, float dt) {
+
+  const float entropy = p->entropy + p->entropy_dt * dt;
+
+  return gas_internal_energy_from_entropy(p->rho, entropy);
+}
+
+/**
+ * @brief Returns the pressure of a particle
+ *
+ * @param p The particle of interest
+ * @param dt Time since the last kick
+ */
+__attribute__((always_inline)) INLINE static float hydro_get_pressure(
+    const struct part *restrict p, float dt) {
+
+  const float entropy = p->entropy + p->entropy_dt * dt;
+
+  return gas_pressure_from_entropy(p->rho, entropy);
+}
+
+/**
+ * @brief Returns the entropy of a particle
+ *
+ * @param p The particle of interest
+ * @param dt Time since the last kick
+ */
+__attribute__((always_inline)) INLINE static float hydro_get_entropy(
+    const struct part *restrict p, float dt) {
+
+  return p->entropy + p->entropy_dt * dt;
+}
+
+/**
+ * @brief Returns the sound speed of a particle
+ *
+ * @param p The particle of interest
+ * @param dt Time since the last kick
+ */
+__attribute__((always_inline)) INLINE static float hydro_get_soundspeed(
+    const struct part *restrict p, float dt) {
+
+  return p->force.soundspeed;
+}
+
+/**
+ * @brief Modifies the thermal state of a particle to the imposed internal
+ * energy
+ *
+ * This overrides the current state of the particle but does *not* change its
+ * time-derivatives
+ *
+ * @param p The particle
+ * @param u The new internal energy
+ */
+__attribute__((always_inline)) INLINE static void hydro_set_internal_energy(
+    struct part *restrict p, float u) {
+
+  p->entropy = gas_entropy_from_internal_energy(p->rho, u);
+}
+
+/**
+ * @brief Modifies the thermal state of a particle to the imposed entropy
+ *
+ * This overrides the current state of the particle but does *not* change its
+ * time-derivatives
+ *
+ * @param p The particle
+ * @param S The new entropy
+ */
+__attribute__((always_inline)) INLINE static void hydro_set_entropy(
+    struct part *restrict p, float S) {
+
+  p->entropy = S;
+}
+
+/**
+ * @brief Computes the hydro time-step of a given particle
+ *
+ * @param p Pointer to the particle data
+ * @param xp Pointer to the extended particle data
+ *
+ */
+__attribute__((always_inline)) INLINE static float hydro_compute_timestep(
+    const struct part *restrict p, const struct xpart *restrict xp,
+    const struct hydro_props *restrict hydro_properties) {
+
+  const float CFL_condition = hydro_properties->CFL_condition;
+
+  /* CFL condition */
+  const float dt_cfl =
+      2.f * kernel_gamma * CFL_condition * p->h / p->force.v_sig;
+
+  return dt_cfl;
+}
+
+/**
+ * @brief Initialises the particles for the first time
+ *
+ * This function is called only once just after the ICs have been
+ * read in to do some conversions.
+ *
+ * @param p The particle to act upon
+ * @param xp The extended particle data to act upon
+ */
+__attribute__((always_inline)) INLINE static void hydro_first_init_part(
+    struct part *restrict p, struct xpart *restrict xp) {
+
+  p->ti_begin = 0;
+  p->ti_end = 0;
+  xp->v_full[0] = p->v[0];
+  xp->v_full[1] = p->v[1];
+  xp->v_full[2] = p->v[2];
+}
+
+/**
+ * @brief Prepares a particle for the density calculation.
+ *
+ * Zeroes all the relevant arrays in preparation for the sums taking place in
+ * the variaous density tasks
+ *
+ * @param p The particle to act upon
+ */
+__attribute__((always_inline)) INLINE static void hydro_init_part(
+    struct part *restrict p) {
+  p->density.wcount = 0.f;
+  p->density.wcount_dh = 0.f;
+  p->rho = 0.f;
+  p->rho_dh = 0.f;
+  p->density.div_v = 0.f;
+  p->density.rot_v[0] = 0.f;
+  p->density.rot_v[1] = 0.f;
+  p->density.rot_v[2] = 0.f;
+}
+
+/**
+ * @brief Finishes the density calculation.
+ *
+ * Multiplies the density and number of neighbours by the appropiate constants
+ * and add the self-contribution term.
+ *
+ * @param p The particle to act upon
+ * @param ti_current The current time (on the integer timeline)
+ */
+__attribute__((always_inline)) INLINE static void hydro_end_density(
+    struct part *restrict p, int ti_current) {
+
+  /* Some smoothing length multiples. */
+  const float h = p->h;
+  const float h_inv = 1.0f / h;                       /* 1/h */
+  const float h_inv_dim = pow_dimension(h_inv);       /* 1/h^d */
+  const float h_inv_dim_plus_one = h_inv_dim * h_inv; /* 1/h^(d+1) */
+
+  /* Final operation on the density (add self-contribution). */
+  p->rho += p->mass * kernel_root;
+  p->rho_dh -= hydro_dimension * p->mass * kernel_root;
+  p->density.wcount += kernel_root;
+
+  /* Finish the calculation by inserting the missing h-factors */
+  p->rho *= h_inv_dim;
+  p->rho_dh *= h_inv_dim_plus_one;
+  p->density.wcount *= kernel_norm;
+  p->density.wcount_dh *= h_inv * kernel_gamma * kernel_norm;
+
+  const float irho = 1.f / p->rho;
+
+  /* Compute the derivative term */
+  p->rho_dh = 1.f / (1.f + hydro_dimension_inv * p->h * p->rho_dh * irho);
+
+  /* Finish calculation of the velocity curl components */
+  p->density.rot_v[0] *= h_inv_dim_plus_one * irho;
+  p->density.rot_v[1] *= h_inv_dim_plus_one * irho;
+  p->density.rot_v[2] *= h_inv_dim_plus_one * irho;
+
+  /* Finish calculation of the velocity divergence */
+  p->density.div_v *= h_inv_dim_plus_one * irho;
+}
+
+/**
+ * @brief Prepare a particle for the force calculation.
+ *
+ * Computes viscosity term, conduction term and smoothing length gradient terms.
+ *
+ * @param p The particle to act upon
+ * @param xp The extended particle data to act upon
+ * @param ti_current The current time (on the timeline)
+ * @param timeBase The minimal time-step size
+ */
+__attribute__((always_inline)) INLINE static void hydro_prepare_force(
+    struct part *restrict p, struct xpart *restrict xp, int ti_current,
+    double timeBase) {
+
+  const float fac_mu = 1.f; /* Will change with cosmological integration */
+
+  /* Compute the norm of the curl */
+  const float curl_v = sqrtf(p->density.rot_v[0] * p->density.rot_v[0] +
+                             p->density.rot_v[1] * p->density.rot_v[1] +
+                             p->density.rot_v[2] * p->density.rot_v[2]);
+
+  /* Compute the norm of div v */
+  const float abs_div_v = fabsf(p->density.div_v);
+
+  /* Compute the pressure */
+  const float half_dt = (ti_current - (p->ti_begin + p->ti_end) / 2) * timeBase;
+  const float pressure = hydro_get_pressure(p, half_dt);
+
+  const float irho = 1.f / p->rho;
+
+  /* Divide the pressure by the density and density gradient */
+  const float P_over_rho2 = pressure * irho * irho * p->rho_dh;
+
+  /* Compute the sound speed */
+  const float soundspeed = sqrtf(hydro_gamma * pressure * irho);
+
+  /* Compute the Balsara switch */
+  const float balsara =
+      abs_div_v / (abs_div_v + curl_v + 0.0001f * soundspeed / fac_mu / p->h);
+
+  /* Update variables. */
+  p->force.P_over_rho2 = P_over_rho2;
+  p->force.soundspeed = soundspeed;
+  p->force.balsara = balsara;
+}
+
+/**
+ * @brief Reset acceleration fields of a particle
+ *
+ * Resets all hydro acceleration and time derivative fields in preparation
+ * for the sums taking place in the variaous force tasks
+ *
+ * @param p The particle to act upon
+ */
+__attribute__((always_inline)) INLINE static void hydro_reset_acceleration(
+    struct part *restrict p) {
+
+  /* Reset the acceleration. */
+  p->a_hydro[0] = 0.0f;
+  p->a_hydro[1] = 0.0f;
+  p->a_hydro[2] = 0.0f;
+
+  /* Reset the time derivatives. */
+  p->entropy_dt = 0.0f;
+  p->force.h_dt = 0.0f;
+
+  /* Reset maximal signal velocity */
+  p->force.v_sig = 0.0f;
+}
+
+/**
+ * @brief Predict additional particle fields forward in time when drifting
+ *
+ * @param p The particle
+ * @param xp The extended data of the particle
+ * @param t0 The time at the start of the drift
+ * @param t1 The time at the end of the drift
+ * @param timeBase The minimal time-step size
+ */
+__attribute__((always_inline)) INLINE static void hydro_predict_extra(
+    struct part *restrict p, const struct xpart *restrict xp, int t0, int t1,
+    double timeBase) {
+
+  /* Drift the pressure */
+  const float dt_entr = (t1 - (p->ti_begin + p->ti_end) / 2) * timeBase;
+  const float pressure = hydro_get_pressure(p, dt_entr);
+
+  const float irho = 1.f / p->rho;
+
+  /* Divide the pressure by the density and density gradient */
+  const float P_over_rho2 = pressure * irho * irho * p->rho_dh;
+
+  /* Compute the new sound speed */
+  const float soundspeed = sqrtf(hydro_gamma * pressure * irho);
+
+  /* Update variables */
+  p->force.P_over_rho2 = P_over_rho2;
+  p->force.soundspeed = soundspeed;
+}
+
+/**
+ * @brief Finishes the force calculation.
+ *
+ * Multiplies the forces and accelerationsby the appropiate constants
+ *
+ * @param p The particle to act upon
+ */
+__attribute__((always_inline)) INLINE static void hydro_end_force(
+    struct part *restrict p) {
+
+  p->force.h_dt *= p->h * hydro_dimension_inv;
+
+  p->entropy_dt *=
+      0.5f * hydro_gamma_minus_one * pow_minus_gamma_minus_one(p->rho);
+}
+
+/**
+ * @brief Kick the additional variables
+ *
+ * @param p The particle to act upon
+ * @param xp The particle extended data to act upon
+ * @param dt The time-step for this kick
+ * @param half_dt The half time-step for this kick
+ */
+__attribute__((always_inline)) INLINE static void hydro_kick_extra(
+    struct part *restrict p, struct xpart *restrict xp, float dt,
+    float half_dt) {
+
+  /* Do not decrease the entropy (temperature) by more than a factor of 2*/
+  const float entropy_change = p->entropy_dt * dt;
+  if (entropy_change > -0.5f * p->entropy)
+    p->entropy += entropy_change;
+  else
+    p->entropy *= 0.5f;
+
+  /* Do not 'overcool' when timestep increases */
+  if (p->entropy + p->entropy_dt * half_dt < 0.5f * p->entropy)
+    p->entropy_dt = -0.5f * p->entropy / half_dt;
+}
+
+/**
+ *  @brief Converts hydro quantity of a particle at the start of a run
+ *
+ * Requires the density to be known
+ *
+ * @param p The particle to act upon
+ */
+__attribute__((always_inline)) INLINE static void hydro_convert_quantities(
+    struct part *restrict p) {
+
+  /* We read u in the entropy field. We now get S from u */
+  p->entropy = gas_entropy_from_internal_energy(p->rho, p->entropy);
+}
+
+#endif /* SWIFT_PRESSURE_ENTROPY_HYDRO_H */

src/hydro/PressureEntropy/hydro_debug.h

+/*******************************************************************************
+ * This file is part of SWIFT.
+ * Coypright (c) 2016 Matthieu Schaller (matthieu.schaller@durham.ac.uk)
+ *
+ * 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_PRESSURE_ENTROPY_HYDRO_DEBUG_H
+#define SWIFT_PRESSURE_ENTROPY_HYDRO_DEBUG_H
+
+/**
+ * @file PressureEntropy/hydro_debug.h
+ * @brief Pressure-Entropy implementation of SPH (Particle definition)
+ *
+ * The thermal variable is the entropy (S) and the entropy is smoothed over
+ * contact discontinuities to prevent spurious surface tension.
+ *
+ * Follows Hopkins, P., MNRAS, 2013, Volume 428, Issue 4, pp. 2840-2856
+ */
+
+__attribute__((always_inline)) INLINE static void hydro_debug_particle(
+    const struct part* p, const struct xpart* xp) {
+  printf(
+      "x=[%.3e,%.3e,%.3e], "
+      "v=[%.3e,%.3e,%.3e],v_full=[%.3e,%.3e,%.3e] \n a=[%.3e,%.3e,%.3e],\n "
+      "h=%.3e, wcount=%.3f, wcount_dh=%.3e, m=%.3e, dh_drho=%.3e, rho=%.3e, "
+      "P=%.3e, P_over_rho2=%.3e, S=%.3e, dS/dt=%.3e, c=%.3e\n"
+      "divV=%.3e, rotV=[%.3e,%.3e,%.3e], balsara=%.3e \n "
+      "v_sig=%e dh/dt=%.3e t_begin=%d, t_end=%d\n",
+      p->x[0], p->x[1], p->x[2], p->v[0], p->v[1], p->v[2], xp->v_full[0],
+      xp->v_full[1], xp->v_full[2], p->a_hydro[0], p->a_hydro[1], p->a_hydro[2],
+      p->h, p->density.wcount, p->density.wcount_dh, p->mass, p->rho_dh, p->rho,
+      hydro_get_pressure(p, 0.), p->force.P_over_rho2, p->entropy,
+      p->entropy_dt, p->force.soundspeed, p->density.div_v, p->density.rot_v[0],
+      p->density.rot_v[1], p->density.rot_v[2], p->force.balsara,
+      p->force.v_sig, p->force.h_dt, p->ti_begin, p->ti_end);
+}
+
+#endif /* SWIFT_PRESSURE_ENTROPY_HYDRO_DEBUG_H */

src/hydro/PressureEntropy/hydro_iact.h

+/*******************************************************************************
+ * This file is part of SWIFT.
+ * Copyright (c) 2016 Matthieu Schaller (matthieu.schaller@durham.ac.uk)
+ *
+ * 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_PRESSURE_ENTROPY_HYDRO_IACT_H
+#define SWIFT_PRESSURE_ENTROPY_HYDRO_IACT_H
+
+/**
+ * @file PressureEntropy/hydro_part.h
+ * @brief Pressure-Entropy implementation of SPH (Particle definition)
+ *
+ * The thermal variable is the entropy (S) and the entropy is smoothed over
+ * contact discontinuities to prevent spurious surface tension.
+ *
+ * Follows Hopkins, P., MNRAS, 2013, Volume 428, Issue 4, pp. 2840-2856
+ */
+
+/**
+ * @brief Density loop
+ */
+__attribute__((always_inline)) INLINE static void runner_iact_density(
+    float r2, float *dx, float hi, float hj, struct part *pi, struct part *pj) {
+
+  float wi, wi_dx;
+  float wj, wj_dx;
+  float dv[3], curlvr[3];
+
+  /* Get the masses. */
+  const float mi = pi->mass;
+  const float mj = pj->mass;
+
+  /* Get r and r inverse. */
+  const float r = sqrtf(r2);
+  const float r_inv = 1.0f / r;
+
+  /* Compute the kernel function for pi */
+  const float hi_inv = 1.f / hi;
+  const float ui = r * hi_inv;
+  kernel_deval(ui, &wi, &wi_dx);
+
+  /* Compute contribution to the density */
+  pi->rho += mj * wi;
+  pi->rho_dh -= mj * (hydro_dimension * wi + ui * wi_dx);
+
+  /* Compute contribution to the number of neighbours */
+  pi->density.wcount += wi;
+  pi->density.wcount_dh -= ui * wi_dx;
+
+  /* Compute the kernel function for pj */
+  const float hj_inv = 1.f / hj;
+  const float uj = r * hj_inv;
+  kernel_deval(uj, &wj, &wj_dx);
+
+  /* Compute contribution to the density */
+  pj->rho += mi * wj;
+  pj->rho_dh -= mi * (hydro_dimension * wj + uj * wj_dx);
+
+  /* Compute contribution to the number of neighbours */
+  pj->density.wcount += wj;
+  pj->density.wcount_dh -= uj * wj_dx;
+
+  const float faci = mj * wi_dx * r_inv;
+  const float facj = mi * wj_dx * r_inv;
+
+  /* Compute dv dot r */
+  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];
+}
+
+/**
+ * @brief Density loop (Vectorized version)
+ */
+__attribute__((always_inline)) INLINE static void runner_iact_vec_density(
+    float *R2, float *Dx, float *Hi, float *Hj, struct part **pi,
+    struct part **pj) {
+
+  error("Vectorized version of Pressure-Entropy SPH routine not existatn yet.");
+}
+
+/**
+ * @brief Density loop (non-symmetric version)
+ */
+__attribute__((always_inline)) INLINE static void runner_iact_nonsym_density(
+    float r2, float *dx, float hi, float hj, struct part *pi, struct part *pj) {
+
+  float wi, wi_dx;
+  float dv[3], curlvr[3];
+
+  /* Get the masses. */
+  const float mj = pj->mass;
+
+  /* Get r and r inverse. */
+  const float r = sqrtf(r2);
+  const float ri = 1.0f / r;
+
+  /* Compute the kernel function */
+  const float h_inv = 1.0f / hi;
+  const float u = r * h_inv;
+  kernel_deval(u, &wi, &wi_dx);
+
+  /* Compute contribution to the density */
+  pi->rho += mj * wi;
+  pi->rho_dh -= mj * (hydro_dimension * wi + u * wi_dx);
+
+  /* Compute contribution to the number of neighbours */
+  pi->density.wcount += wi;
+  pi->density.wcount_dh -= u * wi_dx;
+
+  const float fac = mj * wi_dx * ri;
+
+  /* Compute dv dot r */
+  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];