Merge branch 'master' into gravity_multi_dt

.gitignore

@@ -73,6 +73,9 @@ tests/testRiemannExact
 tests/testRiemannTRRS
 tests/testRiemannHLLC
 tests/testMatrixInversion
+tests/testVoronoi1D
+tests/testVoronoi2D
+tests/testVoronoi3D
 tests/testDump
 tests/testLogger
 tests/benchmarkInteractions

configure.ac

@@ -460,7 +460,6 @@ fi
 
 # Check for HDF5. This is required.
 AX_LIB_HDF5
-
 if test "$with_hdf5" != "yes"; then
     AC_MSG_ERROR([Could not find a working HDF5 library])
 fi
@@ -468,8 +467,6 @@ fi
 # We want to know if this HDF5 supports MPI and whether we should use it.
 # The default is to use MPI support if it is available, i.e. this is
 # a parallel HDF5.
-# To do this need to ask the HDF5 compiler about its configuration,
-# -showconfig should have yes/no.
 have_parallel_hdf5="no"
 if test "$with_hdf5" = "yes"; then
     AC_ARG_ENABLE([parallel-hdf5],
@@ -482,7 +479,14 @@ if test "$with_hdf5" = "yes"; then
 
     if test "$enable_parallel_hdf5" = "yes"; then
         AC_MSG_CHECKING([for HDF5 parallel support])
-        parallel=`$H5CC -showconfig | grep "Parallel HDF5:" | awk '{print $3}'`
+# Check if the library is capable, the header should define H5_HAVE_PARALLEL.
+
+        AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+        #include "hdf5.h"
+        #ifndef H5_HAVE_PARALLEL
+        # error macro not defined
+        #endif
+        ]])], [parallel="yes"], [parallel="no"])
         if test "$parallel" = "yes"; then
             have_parallel_hdf5="yes"
             AC_DEFINE([HAVE_PARALLEL_HDF5],1,[HDF5 library supports parallel access])
@@ -583,7 +587,7 @@ fi
 # Hydro scheme.
 AC_ARG_WITH([hydro],
    [AS_HELP_STRING([--with-hydro=<scheme>],
-      [Hydro dynamics to use @<:@gadget2, minimal, hopkins, default, gizmo default: gadget2@:>@]
+      [Hydro dynamics to use @<:@gadget2, minimal, hopkins, default, gizmo, shadowfax default: gadget2@:>@]
    )],
    [with_hydro="$withval"],
    [with_hydro="gadget2"]
@@ -604,6 +608,9 @@ case "$with_hydro" in
    gizmo)
       AC_DEFINE([GIZMO_SPH], [1], [GIZMO SPH])
    ;; 
+   shadowfax)
+      AC_DEFINE([SHADOWFAX_SPH], [1], [Shadowfax SPH])
+   ;; 
 
    *)
       AC_MSG_ERROR([Unknown hydrodynamics scheme: $with_hydro])

m4/ax_lib_hdf5.m4

@@ -22,7 +22,10 @@
 #     yes  - do check for HDF5 library in standard locations.
 #     path - complete path to the HDF5 helper script h5cc or h5pcc.
 #
-#   SWIFT modification: HDF5 is required, so only path is described.
+#   SWIFT modifications: HDF5 is required, so only path is described,
+#   when the h5cc or h5pcc commands are not available, we check if
+#   HDF5 can be used anyway and no macros are defined except HAVE_HDF5
+#   and with_hdf5.
 #
 #   If HDF5 is successfully found, this macro calls
 #
@@ -155,11 +158,37 @@ if test "$with_hdf5" = "yes"; then
         AC_MSG_CHECKING([Using provided HDF5 C wrapper])
         AC_MSG_RESULT([$H5CC])
     fi
-    AC_MSG_CHECKING([for HDF5 libraries])
     if test ! -f "$H5CC" || test ! -x "$H5CC"; then
-        AC_MSG_RESULT([no])
-        AC_MSG_WARN(m4_case(m4_normalize([$1]),
-            [serial],  [
+
+dnl Check if we already have HDF5 for C.
+        AC_CHECK_HEADER([hdf5.h], [ac_cv_hhdf5_h=yes], [ac_cv_hhdf5_h=no], [AC_INCLUDES_DEFAULT])
+        AC_CHECK_LIB([hdf5], [H5Fcreate], [ac_cv_libhdf5=yes],
+                     [ac_cv_libhdf5=no])
+        if test "$ac_cv_hhdf5_h" = "yes" && test "$ac_cv_libhdf5" = "yes" ; then
+
+dnl Can compile and link, so we have a HDF5, just don't know which version.
+            AC_MSG_CHECKING([for HDF5 libraries])
+            AC_MSG_RESULT([yes])
+            with_hdf5="yes"
+            HDF5_VERSION="unknown"
+            HDF5_LIBS="-lhdf5"
+ 	    AC_SUBST([HDF5_VERSION])
+	    AC_SUBST([HDF5_CC])
+	    AC_SUBST([HDF5_CFLAGS])
+	    AC_SUBST([HDF5_CPPFLAGS])
+	    AC_SUBST([HDF5_LDFLAGS])
+	    AC_SUBST([HDF5_LIBS])
+	    AC_SUBST([HDF5_FC])
+	    AC_SUBST([HDF5_FFLAGS])
+	    AC_SUBST([HDF5_FLIBS])
+	    AC_DEFINE([HAVE_HDF5], [1], [Defined if you have HDF5 support])
+        else
+
+dnl Time to give up.
+            AC_MSG_CHECKING([for HDF5 libraries])
+            AC_MSG_RESULT([no])
+            AC_MSG_WARN(m4_case(m4_normalize([$1]),
+                    [serial],  [
 Unable to locate serial HDF5 compilation helper script 'h5cc'.
 Please specify --with-hdf5=<LOCATION> as the full path to h5cc.
 HDF5 support is being disabled.
@@ -172,9 +201,12 @@ Unable to locate HDF5 compilation helper scripts 'h5cc' or 'h5pcc'.
 Please specify --with-hdf5=<LOCATION> as the full path to h5cc or h5pcc.
 HDF5 support is being disabled.
 ]))
-        with_hdf5="no"
-        with_hdf5_fortran="no"
+            with_hdf5="no"
+            with_hdf5_fortran="no"
+        fi
     else
+        AC_MSG_CHECKING([for HDF5 libraries])
+
         dnl Get the h5cc output
         HDF5_SHOW=$(eval $H5CC -show)
 

src/Makefile.am

@@ -46,7 +46,7 @@ include_HEADERS = space.h runner.h queue.h task.h lock.h cell.h part.h const.h \
     hydro_properties.h riemann.h threadpool.h cooling.h cooling_struct.h sourceterms.h \
     sourceterms_struct.h statistics.h memswap.h cache.h runner_doiact_vec.h profiler.h \
     dump.h logger.h active.h timeline.h xmf.h gravity_properties.h gravity_derivatives.h \
-    vector_power.h
+    vector_power.h hydro_space.h
 
 # Common source files
 AM_SOURCES = space.c runner.c queue.c task.c cell.c engine.c \
@@ -56,7 +56,8 @@ AM_SOURCES = space.c runner.c queue.c task.c cell.c engine.c \
     physical_constants.c potential.c hydro_properties.c \
     runner_doiact_fft.c threadpool.c cooling.c sourceterms.c \
     statistics.c runner_doiact_vec.c profiler.c dump.c logger.c \
-    part_type.c xmf.c gravity_properties.c gravity.c
+    part_type.c xmf.c gravity_properties.c gravity.c \
+    hydro_space.c
 
 # Include files for distribution, not installation.
 nobase_noinst_HEADERS = align.h approx_math.h atomic.h cycle.h error.h inline.h kernel_hydro.h kernel_gravity.h \

src/const.h

@@ -54,6 +54,23 @@
 //#define GIZMO_FIX_PARTICLES
 //#define GIZMO_TOTAL_ENERGY
 
+/* Types of gradients to use for SHADOWFAX_SPH */
+/* If no option is chosen, no gradients are used (first order scheme) */
+#define SHADOWFAX_GRADIENTS
+
+/* SHADOWFAX_SPH slope limiters */
+#define SHADOWFAX_SLOPE_LIMITER_PER_FACE
+#define SHADOWFAX_SLOPE_LIMITER_CELL_WIDE
+
+/* Options to control SHADOWFAX_SPH */
+/* This option disables cell movement */
+//#define SHADOWFAX_FIX_CELLS
+/* This option enables cell steering, i.e. trying to keep the cells regular by
+   adding a correction to the cell velocities.*/
+#define SHADOWFAX_STEER_CELL_MOTION
+/* This option evolves the total energy instead of the thermal energy */
+//#define SHADOWFAX_TOTAL_ENERGY
+
 /* Source terms */
 #define SOURCETERMS_NONE
 //#define SOURCETERMS_SN_FEEDBACK

src/debug.c

@@ -49,6 +49,8 @@
 #include "./hydro/Default/hydro_debug.h"
 #elif defined(GIZMO_SPH)
 #include "./hydro/Gizmo/hydro_debug.h"
+#elif defined(SHADOWFAX_SPH)
+#include "./hydro/Shadowswift/hydro_debug.h"
 #else
 #error "Invalid choice of SPH variant"
 #endif

src/hydro.h

@@ -47,6 +47,11 @@
 #include "./hydro/Gizmo/hydro.h"
 #include "./hydro/Gizmo/hydro_iact.h"
 #define SPH_IMPLEMENTATION "GIZMO (Hopkins 2015)"
+#elif defined(SHADOWFAX_SPH)
+#include "./hydro/Shadowswift/hydro.h"
+#include "./hydro/Shadowswift/hydro_iact.h"
+#define SPH_IMPLEMENTATION \
+  "Shadowfax moving mesh (Vandenbroucke and De Rijcke 2016)"
 #else
 #error "Invalid choice of SPH variant"
 #endif

src/hydro/Default/hydro.h

@@ -22,6 +22,7 @@
 #include "adiabatic_index.h"
 #include "approx_math.h"
 #include "equation_of_state.h"
+#include "hydro_space.h"
 #include "minmax.h"
 
 #include <float.h>
@@ -165,9 +166,10 @@ __attribute__((always_inline)) INLINE static void hydro_timestep_extra(
  * the variaous density tasks
  *
  * @param p The particle to act upon
+ * @param hs #hydro_space containing hydro specific space information.
  */
 __attribute__((always_inline)) INLINE static void hydro_init_part(
-    struct part *restrict p) {
+    struct part *restrict p, const struct hydro_space *hs) {
   p->density.wcount = 0.f;
   p->density.wcount_dh = 0.f;
   p->rho = 0.f;
@@ -400,7 +402,7 @@ __attribute__((always_inline)) INLINE static void hydro_first_init_part(
   xp->u_full = p->u;
 
   hydro_reset_acceleration(p);
-  hydro_init_part(p);
+  hydro_init_part(p, NULL);
 }
 
 #endif /* SWIFT_DEFAULT_HYDRO_H */

src/hydro/Gadget2/hydro.h

@@ -36,6 +36,7 @@
 #include "dimension.h"
 #include "equation_of_state.h"
 #include "hydro_properties.h"
+#include "hydro_space.h"
 #include "kernel_hydro.h"
 #include "minmax.h"
 
@@ -169,9 +170,10 @@ __attribute__((always_inline)) INLINE static void hydro_timestep_extra(
  * the variaous density tasks
  *
  * @param p The particle to act upon
+ * @param hs #hydro_space containing hydro specific space information.
  */
 __attribute__((always_inline)) INLINE static void hydro_init_part(
-    struct part *restrict p) {
+    struct part *restrict p, const struct hydro_space *hs) {
 
   p->rho = 0.f;
   p->density.wcount = 0.f;
@@ -456,7 +458,7 @@ __attribute__((always_inline)) INLINE static void hydro_first_init_part(
   xp->entropy_full = p->entropy;
 
   hydro_reset_acceleration(p);
-  hydro_init_part(p);
+  hydro_init_part(p, NULL);
 }
 
 #endif /* SWIFT_GADGET2_HYDRO_H */

src/hydro/Gizmo/hydro.h

@@ -23,6 +23,7 @@
 #include "approx_math.h"
 #include "equation_of_state.h"
 #include "hydro_gradients.h"
+#include "hydro_space.h"
 #include "minmax.h"
 #include "riemann.h"
 
@@ -145,9 +146,10 @@ __attribute__((always_inline)) INLINE static void hydro_first_init_part(
  * Simply makes sure all necessary variables are initialized to zero.
  *
  * @param p The particle to act upon
+ * @param hs #hydro_space containing hydro specific space information.
  */
 __attribute__((always_inline)) INLINE static void hydro_init_part(
-    struct part* p) {
+    struct part* p, const struct hydro_space* hs) {
 
   p->density.wcount = 0.0f;
   p->density.wcount_dh = 0.0f;

src/hydro/Minimal/hydro.h

@@ -38,6 +38,7 @@
 #include "dimension.h"
 #include "equation_of_state.h"
 #include "hydro_properties.h"
+#include "hydro_space.h"
 #include "kernel_hydro.h"
 #include "minmax.h"
 
@@ -183,9 +184,10 @@ __attribute__((always_inline)) INLINE static void hydro_timestep_extra(
  * density sub-structure of a particle get zeroed in here.
  *
  * @param p The particle to act upon
+ * @param hs #hydro_space containing hydro specific space information.
  */
 __attribute__((always_inline)) INLINE static void hydro_init_part(
-    struct part *restrict p) {
+    struct part *restrict p, const struct hydro_space *hs) {
 
   p->density.wcount = 0.f;
   p->density.wcount_dh = 0.f;
@@ -429,7 +431,7 @@ __attribute__((always_inline)) INLINE static void hydro_first_init_part(
   xp->u_full = p->u;
 
   hydro_reset_acceleration(p);
-  hydro_init_part(p);
+  hydro_init_part(p, NULL);
 }
 
 #endif /* SWIFT_MINIMAL_HYDRO_H */

src/hydro/PressureEntropy/hydro.h

@@ -36,6 +36,7 @@
 #include "dimension.h"
 #include "equation_of_state.h"
 #include "hydro_properties.h"
+#include "hydro_space.h"
 #include "kernel_hydro.h"
 #include "minmax.h"
 
@@ -169,9 +170,10 @@ __attribute__((always_inline)) INLINE static void hydro_timestep_extra(
  * the variaous density tasks
  *
  * @param p The particle to act upon
+ * @param hs #hydro_space containing hydro specific space information.
  */
 __attribute__((always_inline)) INLINE static void hydro_init_part(
-    struct part *restrict p) {
+    struct part *restrict p, const struct hydro_space *hs) {
 
   p->rho = 0.f;
   p->rho_bar = 0.f;
@@ -474,7 +476,7 @@ __attribute__((always_inline)) INLINE static void hydro_first_init_part(
   xp->v_full[2] = p->v[2];
 
   hydro_reset_acceleration(p);
-  hydro_init_part(p);
+  hydro_init_part(p, NULL);
 }
 
 #endif /* SWIFT_PRESSURE_ENTROPY_HYDRO_H */

src/hydro/Shadowswift/hydro.h

+/*******************************************************************************
+ * This file is part of SWIFT.
+ * Copyright (c) 2016 Bert Vandenbroucke (bert.vandenbroucke@gmail.com).
+ *
+ * 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/>.
+ *
+ ******************************************************************************/
+
+#include <float.h>
+#include "adiabatic_index.h"
+#include "approx_math.h"
+#include "equation_of_state.h"
+#include "hydro_gradients.h"
+#include "hydro_space.h"
+#include "voronoi_algorithm.h"
+
+/**
+ * @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.
+ * @param hydro_properties Pointer to the hydro parameters.
+ */
+__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;
+
+  float R = get_radius_dimension_sphere(p->cell.volume);
+
+  if (p->timestepvars.vmax == 0.) {
+    /* vmax can be zero in vacuum. We force the time step to become the maximal
+       time step in this case */
+    return FLT_MAX;
+  } else {
+    return CFL_condition * R / fabsf(p->timestepvars.vmax);
+  }
+}
+
+/**
+ * @brief Does some extra hydro operations once the actual physical time step
+ * for the particle is known.
+ *
+ * We use this to store the physical time step, since it is used for the flux
+ * exchange during the force loop.
+ *
+ * We also set the active flag of the particle to inactive. It will be set to
+ * active in hydro_init_part, which is called the next time the particle becomes
+ * active.
+ *
+ * @param p The particle to act upon.
+ * @param dt Physical time step of the particle during the next step.
+ */
+__attribute__((always_inline)) INLINE static void hydro_timestep_extra(
+    struct part* p, float dt) {
+
+  p->force.dt = dt;
+  p->force.active = 0;
+}
+
+/**
+ * @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.
+ *
+ * In this case, we copy the particle velocities into the corresponding
+ * primitive variable field. We do this because the particle velocities in GIZMO
+ * can be independent of the actual fluid velocity. The latter is stored as a
+ * primitive variable and integrated using the linear momentum, a conserved
+ * variable.
+ *
+ * @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* p, struct xpart* xp) {
+
+  const float mass = p->conserved.mass;
+
+  p->primitives.v[0] = p->v[0];
+  p->primitives.v[1] = p->v[1];
+  p->primitives.v[2] = p->v[2];
+
+  p->conserved.momentum[0] = mass * p->primitives.v[0];
+  p->conserved.momentum[1] = mass * p->primitives.v[1];
+  p->conserved.momentum[2] = mass * p->primitives.v[2];
+
+#ifdef EOS_ISOTHERMAL_GAS
+  p->conserved.energy = mass * const_isothermal_internal_energy;
+#else
+  p->conserved.energy *= mass;
+#endif
+
+#ifdef SHADOWFAX_TOTAL_ENERGY
+  p->conserved.energy += 0.5f * (p->conserved.momentum[0] * p->primitives.v[0] +
+                                 p->conserved.momentum[1] * p->primitives.v[1] +
+                                 p->conserved.momentum[2] * p->primitives.v[2]);
+#endif
+
+#if defined(SHADOWFAX_FIX_CELLS)
+  p->v[0] = 0.;
+  p->v[1] = 0.;
+  p->v[2] = 0.;
+#endif
+
+  /* set the initial velocity of the cells */
+  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 volume calculation.
+ *
+ * Simply makes sure all necessary variables are initialized to zero.
+ * Initializes the Voronoi cell.
+ *
+ * @param p The particle to act upon
+ * @param hs #hydro_space containing extra information about the space.
+ */
+__attribute__((always_inline)) INLINE static void hydro_init_part(
+    struct part* p, const struct hydro_space* hs) {
+
+  p->density.wcount = 0.0f;
+  p->density.wcount_dh = 0.0f;
+
+  voronoi_cell_init(&p->cell, p->x, hs->anchor, hs->side);
+
+  /* Set the active flag to active. */
+  p->force.active = 1;
+}
+
+/**
+ * @brief Finishes the volume calculation.
+ *
+ * Calls the finalize method on the Voronoi cell, which calculates the volume
+ * and centroid of the cell. We use the return value of this function to set
+ * a new value for the smoothing length and possibly force another iteration
+ * of the volume calculation for this particle. We then use the volume to
+ * convert conserved variables into primitive variables.
+ *
+ * This method also initializes the gradient variables (if gradients are used).
+ *
+ * @param p The particle to act upon.
+ */
+__attribute__((always_inline)) INLINE static void hydro_end_density(
+    struct part* restrict p) {
+
+  float volume;
+  float m, momentum[3], energy;
+
+  hydro_gradients_init(p);
+
+  float hnew = voronoi_cell_finalize(&p->cell);
+  /* Enforce hnew as new smoothing length in the iteration
+     This is annoyingly difficult, as we do not have access to the variables
+     that govern the loop...
+     So here's an idea: let's force in some method somewhere that makes sure
+     r->e->hydro_properties->target_neighbours is 1, and
+     r->e->hydro_properties->delta_neighbours is 0.
+     This way, we can accept an iteration by setting p->density.wcount to 1.
+     To get the right correction for h, we set wcount to something else
+     (say 0), and then set p->density.wcount_dh to 1/(hnew-h). */
+  if (hnew < p->h) {
+    /* Iteration succesful: we accept, but manually set h to a smaller value
+       for the next time step */
+    p->density.wcount = 1.0f;
+    p->h = 1.1f * hnew;
+  } else {
+    /* Iteration not succesful: we force h to become 1.1*hnew */
+    p->density.wcount = 0.0f;
+    p->density.wcount_dh = 1.0f / (1.1f * hnew - p->h);
+    return;
+  }
+  volume = p->cell.volume;
+
+#ifdef SWIFT_DEBUG_CHECKS
+  /* the last condition checks for NaN: a NaN value always evaluates to false,
+     even when checked against itself */
+  if (volume == 0. || volume == INFINITY || volume != volume) {
+    error("Invalid value for cell volume (%g)!", volume);
+  }
+#endif
+
+  /* compute primitive variables */
+  /* eqns (3)-(5) */
+  m = p->conserved.mass;
+  if (m > 0.) {
+    momentum[0] = p->conserved.momentum[0];
+    momentum[1] = p->conserved.momentum[1];
+    momentum[2] = p->conserved.momentum[2];
+    p->primitives.rho = m / volume;
+    p->primitives.v[0] = momentum[0] / m;
+    p->primitives.v[1] = momentum[1] / m;
+    p->primitives.v[2] = momentum[2] / m;
+
+    energy = p->conserved.energy;
+
+#ifdef SHADOWFAX_TOTAL_ENERGY
+    energy -= 0.5f * (momentum[0] * p->primitives.v[0] +
+                      momentum[1] * p->primitives.v[1] +
+                      momentum[2] * p->primitives.v[2]);
+#endif
+
+    energy /= m;
+
+    p->primitives.P =
+        gas_pressure_from_internal_energy(p->primitives.rho, energy);
+  } else {
+    p->primitives.rho = 0.;
+    p->primitives.v[0] = 0.;
+    p->primitives.v[1] = 0.;
+    p->primitives.v[2] = 0.;
+    p->primitives.P = 0.;
+  }
+
+#ifdef SWIFT_DEBUG_CHECKS
+  if (p->primitives.rho < 0.) {
+    error("Negative density!");
+  }
+
+  if (p->primitives.P < 0.) {
+    error("Negative pressure!");
+  }
+#endif
+}
+
+/**
+ * @brief Prepare a particle for the gradient calculation.
+ *
+ * The name of this method is confusing, as this method is really called after
+ * the density loop and before the gradient loop.
+ *
+ * We use it to set the physical timestep for the particle and to copy the
+ * actual velocities, which we need to boost our interfaces during the flux
+ * calculation. We also initialize the variables used for the time step
+ * calculation.
+ *
+ * @param p The particle to act upon.
+ * @param xp The extended particle data to act upon.
+ */
+__attribute__((always_inline)) INLINE static void hydro_prepare_force(
+    struct part* restrict p, struct xpart* restrict xp) {
+
+  /* Initialize time step criterion variables */
+  p->timestepvars.vmax = 0.0f;
+
+  /* Set the actual velocity of the particle */
+  p->force.v_full[0] = xp->v_full[0];
+  p->force.v_full[1] = xp->v_full[1];
+  p->force.v_full[2] = xp->v_full[2];
+}
+
+/**
+ * @brief Finishes the gradient calculation.
+ *
+ * Just a wrapper around hydro_gradients_finalize, which can be an empty method,
+ * in which case no gradients are used.
+ *
+ * @param p The particle to act upon.
+ */
+__attribute__((always_inline)) INLINE static void hydro_end_gradient(
+    struct part* p) {
+
+  hydro_gradients_finalize(p);
+}
+
+/**
+ * @brief Reset acceleration fields of a particle
+ *
+ * This is actually not necessary for Shadowswift, since we just set the
+ * accelerations after the flux calculation.
+ *
+ * @param p The particle to act upon.
+ */
+__attribute__((always_inline)) INLINE static void hydro_reset_acceleration(
+    struct part* 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->force.h_dt = 0.0f;