Initial high level changes from moving_mesh

configure.ac

@@ -818,6 +818,42 @@ AC_SUBST([GSL_LIBS])
 AC_SUBST([GSL_INCS])
 AM_CONDITIONAL([HAVEGSL],[test -n "$GSL_LIBS"])
 
+# Check for GMP. We test for this in the standard directories by default,
+# and only disable if using --with-gmp=no or --without-gmp. When a value
+# is given GMP must be found.
+have_gmp="no"
+AC_ARG_WITH([gmp],
+    [AS_HELP_STRING([--with-gmp=PATH],
+       [root directory where GMP is installed @<:@yes/no@:>@]
+    )],
+    [with_gmp="$withval"],
+    [with_gmp="test"]
+)
+if test "x$with_gmp" != "xno"; then
+   if test "x$with_gmp" != "xyes" -a "x$with_gmp" != "xtest" -a "x$with_gmp" != "x"; then
+      GMP_LIBS="-L$with_gmp/lib -lgmp"
+   else
+      GMP_LIBS="-lgmp"
+   fi
+   #  GMP is not specified, so just check if we have it.
+   if test "x$with_gmp" = "xtest"; then
+      AC_CHECK_LIB([gmp],[__gmpz_inits],[have_gmp="yes"],[have_gmp="no"],$GMP_LIBS)
+      if test "x$have_gmp" != "xno"; then
+         AC_DEFINE([HAVE_LIBGMP],1,[The GMP library appears to be present.])
+      fi
+   else
+      AC_CHECK_LIB([gmp],[__gmpz_inits],
+         AC_DEFINE([HAVE_LIBGMP],1,[The GMP library appears to be present.]),
+         AC_MSG_ERROR(something is wrong with the GMP library!), $GMP_LIBS)
+      have_gmp="yes"
+   fi
+   if test "$have_gmp" = "no"; then
+      GMP_LIBS=""
+   fi
+fi
+AC_SUBST([GMP_LIBS])
+AM_CONDITIONAL([HAVEGMP],[test -n "$GMP_LIBS"])
+
 # Check for pthreads.
 AX_PTHREAD([LIBS="$PTHREAD_LIBS $LIBS" CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
     CC="$PTHREAD_CC" LDFLAGS="$LDFLAGS $PTHREAD_LIBS $LIBS"],
@@ -2109,7 +2145,7 @@ fi
 # Hydro scheme.
 AC_ARG_WITH([hydro],
    [AS_HELP_STRING([--with-hydro=<scheme>],
-      [Hydro dynamics to use @<:@gadget2, minimal, pressure-entropy, pressure-energy, pressure-energy-monaghan, phantom, gizmo-mfv, gizmo-mfm, shadowfax, planetary, sphenix, gasoline, anarchy-pu default: sphenix@:>@]
+      [Hydro dynamics to use @<:@gadget2, minimal, pressure-entropy, pressure-energy, pressure-energy-monaghan, phantom, gizmo-mfv, gizmo-mfm, shadowswift, planetary, sphenix, gasoline, anarchy-pu default: sphenix@:>@]
    )],
    [with_hydro="$withval"],
    [with_hydro="sphenix"]
@@ -2146,9 +2182,12 @@ case "$with_hydro" in
       AC_DEFINE([GIZMO_MFM_SPH], [1], [GIZMO MFM SPH])
       need_riemann_solver=yes
    ;;
-   shadowfax)
-      AC_DEFINE([SHADOWFAX_SPH], [1], [Shadowfax SPH])
+   shadowswift)
+      AC_DEFINE([SHADOWSWIFT], [1], [ShadowSWIFT hydrodynamics])
+      AC_DEFINE([MOVING_MESH_HYDRO], [1], [Moving mesh hydrodynamics])
+      need_moving_mesh=yes
       need_riemann_solver=yes
+      hydro_does_mass_flux=yes
    ;;
    planetary)
       AC_DEFINE([PLANETARY_SPH], [1], [Planetary SPH])
@@ -2195,8 +2234,8 @@ fi
 if test "$with_hydro" = "gizmo-mfv" -a "$with_spmhd" != "none"; then
   AC_MSG_ERROR([Cannot use an SPMHD scheme alongside a gizmo hydro solver!"])
 fi
-if test "$with_hydro" = "shadowfax" -a "$with_spmhd" != "none"; then
-  AC_MSG_ERROR([Cannot use an SPMHD scheme alongside a gizmo hydro solver!"])
+if test "$with_hydro" = "shadowswift" -a "$with_spmhd" != "none"; then
+  AC_MSG_ERROR([Cannot use an SPMHD scheme alongside a moving mesh hydro solver!"])
 fi
 
 # Check if debugging interactions stars is switched on.
@@ -2425,6 +2464,27 @@ if test "x$need_riemann_solver" = "xyes" -a "$with_riemann" = "none"; then
   AC_MSG_ERROR([Hydro scheme $with_hydro requires selection of a Riemann solver!])
 fi
 
+# Moving mesh
+AC_ARG_ENABLE([moving-mesh],
+    [AS_HELP_STRING([--enable-moving-mesh],
+        [enable the moving mesh computation]
+    )],
+    [enable_moving_mesh="${enableval}"],
+    [enable_moving_mesh="no"]
+)
+if test "x$need_moving_mesh" = "xyes"; then
+    enable_moving_mesh="yes"
+fi
+if test "$enable_moving_mesh" = "yes"; then
+    if test "$have_gmp" = "no"; then
+        AC_MSG_ERROR([GMP is required when using moving mesh!])
+    fi
+    if test "$have_gsl" = "no"; then
+        AC_MSG_ERROR([GSL is required when using moving mesh!])
+    fi
+    AC_DEFINE([MOVING_MESH], [1], [Unstructured Voronoi mesh])
+fi
+
 # Hydro does mass flux?
 if test "x$hydro_does_mass_flux" = "xyes"; then
     AC_DEFINE([HYDRO_DOES_MASS_FLUX], [1], [Hydro scheme with mass fluxes])
@@ -3155,6 +3215,9 @@ AM_CONDITIONAL([HAVESPHM1RTRT], [test "${with_rt:0:7}" = "SPHM1RT"])
 # Check if using GEAR-RT radiative transfer
 AM_CONDITIONAL([HAVEGEARRT], [test "${with_rt:0:4}" = "GEAR"])
 
+# Check if using Moving mesh
+AM_CONDITIONAL([HAVE_MOVING_MESH], [test "$enable_moving_mesh" = "yes"])
+
 
 
 
@@ -3212,6 +3275,7 @@ AC_MSG_RESULT([
     - MPI               : $have_mpi_fftw
     - ARM               : $have_arm_fftw
    GSL enabled          : $have_gsl
+   GMP enabled          : $have_gmp
    HEALPix C enabled    : $have_chealpix
    libNUMA enabled      : $have_numa
    GRACKLE enabled      : $have_grackle
@@ -3222,6 +3286,7 @@ AC_MSG_RESULT([
    VELOCIraptor enabled : $have_velociraptor
    FoF activated:       : $enable_fof
    Lightcones enabled   : $enable_lightcone
+   Moving-mesh enabled  : $enable_moving_mesh
 
    Hydro scheme       : $with_hydro
    Dimensionality     : $with_dimension

doc/RTD/source/HydroSchemes/index.rst

@@ -41,5 +41,6 @@ In case the case of a 2 loop scheme, SWIFT removes the gradient loop and the ext
    phantom_sph
    adaptive_softening
    gizmo
+   shadowswift
    adding_your_own
 

doc/RTD/source/HydroSchemes/shadowswift.rst

@@ -0,0 +1,48 @@
+.. ShadowSWIFT (Moving mesh hydrodynamics)
+   Yolan Uyttenhove September 2023
+
+ShadowSWIFT (moving mesh hydrodynamics)
+=======================================
+
+.. warning::
+    The moving mesh hydrodynamics solver is currently in the process of being merged into master and will **NOT**
+    work on the master branch. To use it, compile the code using the ``moving_mesh`` branch.
+
+This is an implementation of the moving-mesh finite-volume method for hydrodynamics in SWIFT.
+To use this scheme, a Riemann solver is also needed. Configure SWIFT as follows:
+
+.. code-block:: bash
+
+    ./configure --with-hydro="shadowswift" --with-riemann-solver="hllc"
+
+
+Current status
+~~~~~~~~~~~~~~
+
+Due to the completely different task structure compared to SPH hydrodynamics, currently only a subset of the features of
+SWIFT is supported in this scheme.
+
+-   Hydrodynamics is fully supported in 1D, 2D and 3D and over MPI.
+
+-   Both self-gravity and external potentials are supported.
+
+-   Cosmological time-integration is supported.
+
+-   Cooling and chemistry are supported, with the exception of the ``GEAR_diffusion`` chemistry scheme. Metals are
+    properly according to mass fluxes.
+
+-   Choice between periodic, reflective, open, inflow and vacuum boundary conditions (for non-periodic boundary
+    conditions, the desired variant must be selected in ``const.h``). Additionally, reflective boundary conditions
+    are applied to SWIFT's boundary particles. Configure with ``--with-boundary-particles=<N>`` to use this (e.g. to
+    simulate walls).
+
+
+Caveats
+~~~~~~~
+These are currently the main limitations of the ShadowSWIFT hydro scheme:
+
+-   Unlike SPH the cells of the moving mesh must form a partition of the entire simulation volume. This means that there
+    cannot be empty SWIFT cells and vacuum must be explicitly represented by zero (or negligible) mass particles.
+-   Most other subgrid physics, most notably, star formation and stellar feedback are not supported yet.
+-   No MHD schemes are supported.
+-   No radiative-transfer schemes are supported.

examples/parameter_example.yml

@@ -137,6 +137,7 @@ Scheduler:
   cell_sub_size_pair_grav:   256000000 # (Optional) Maximal number of interactions per sub-pair gravity task  (this is the default value).
   cell_sub_size_self_grav:   32000     # (Optional) Maximal number of interactions per sub-self gravity task  (this is the default value).
   cell_split_size:           400       # (Optional) Maximal number of particles per cell (this is the default value).
+  grid_split_threshold:      400       # (Optional) Maximal number of particles per cell at construction level of Voronoi grid (this is the default value).
   cell_subdepth_diff_grav:   4         # (Optional) Maximal depth difference between leaves and a cell that gravity tasks can be pushed down to (this is the default value).
   cell_extra_parts:          0         # (Optional) Number of spare parts per top-level allocated at rebuild time for on-the-fly creation.
   cell_extra_gparts:         0         # (Optional) Number of spare gparts per top-level allocated at rebuild time for on-the-fly creation.