diff --git a/src/hydro/Default/hydro.h b/src/hydro/Default/hydro.h
index e14fc29aefccf8643c19c342ca9ebe645a323db1..f5e71a8762c54faca7d165eb26199d0e30b486ac 100644
--- a/src/hydro/Default/hydro.h
+++ b/src/hydro/Default/hydro.h
@@ -351,16 +351,22 @@ __attribute__((always_inline)) INLINE static void hydro_part_has_no_neighbours(
/**
* @brief Prepare a particle for the force calculation.
*
- * Computes viscosity term, conduction term and smoothing length gradient terms.
+ * This function is called in the ghost task to convert some quantities coming
+ * from the density loop over neighbours into quantities ready to be used in the
+ * force loop over neighbours. Quantities are typically read from the density
+ * sub-structure and written to the force sub-structure.
+ * Examples of calculations done here include the calculation of viscosity term
+ * constants, thermal conduction terms, hydro conversions, etc.
*
* @param p The particle to act upon
* @param xp The extended particle data to act upon
* @param cosmo The current cosmological model.
+ * @param dt_alpha The time-step used to evolve non-cosmological quantities such
+ * as the artificial viscosity.
*/
__attribute__((always_inline)) INLINE static void hydro_prepare_force(
struct part *restrict p, struct xpart *restrict xp,
- const struct cosmology *cosmo) {
-
+ const struct cosmology *cosmo, const float dt_alpha) {
const float fac_mu = cosmo->a_factor_mu;
/* Some smoothing length multiples. */
diff --git a/src/hydro/Gadget2/hydro.h b/src/hydro/Gadget2/hydro.h
index ec46b93f51804b28ce2cb71c134f8c643301e272..0dcd2cf01e9d3b93194fab96af836b6dd045d1f9 100644
--- a/src/hydro/Gadget2/hydro.h
+++ b/src/hydro/Gadget2/hydro.h
@@ -361,15 +361,22 @@ __attribute__((always_inline)) INLINE static void hydro_part_has_no_neighbours(
/**
* @brief Prepare a particle for the force calculation.
*
- * Computes viscosity term, conduction term and smoothing length gradient terms.
+ * This function is called in the ghost task to convert some quantities coming
+ * from the density loop over neighbours into quantities ready to be used in the
+ * force loop over neighbours. Quantities are typically read from the density
+ * sub-structure and written to the force sub-structure.
+ * Examples of calculations done here include the calculation of viscosity term
+ * constants, thermal conduction terms, hydro conversions, etc.
*
* @param p The particle to act upon
* @param xp The extended particle data to act upon
* @param cosmo The current cosmological model.
+ * @param dt_alpha The time-step used to evolve non-cosmological quantities such
+ * as the artificial viscosity.
*/
__attribute__((always_inline)) INLINE static void hydro_prepare_force(
struct part *restrict p, struct xpart *restrict xp,
- const struct cosmology *cosmo) {
+ const struct cosmology *cosmo, const float dt_alpha) {
const float fac_mu = cosmo->a_factor_mu;
diff --git a/src/hydro/GizmoMFM/hydro.h b/src/hydro/GizmoMFM/hydro.h
index e8f116efb30de769acdfd764b7f4dbd03dc91c31..d6b44e19899fdb74ee32f699665ec6e706d718b1 100644
--- a/src/hydro/GizmoMFM/hydro.h
+++ b/src/hydro/GizmoMFM/hydro.h
@@ -441,17 +441,22 @@ __attribute__((always_inline)) INLINE static void hydro_end_gradient(
/**
* @brief Prepare a particle for the force calculation.
*
- * This function is called in the extra_ghost task to convert some quantities
- * coming from the gradient loop over neighbours into quantities ready to be
- * used in the force loop over neighbours.
+ * This function is called in the ghost task to convert some quantities coming
+ * from the density loop over neighbours into quantities ready to be used in the
+ * force loop over neighbours. Quantities are typically read from the density
+ * sub-structure and written to the force sub-structure.
+ * Examples of calculations done here include the calculation of viscosity term
+ * constants, thermal conduction terms, hydro conversions, etc.
*
* @param p The particle to act upon
* @param xp The extended particle data to act upon
* @param cosmo The current cosmological model.
+ * @param dt_alpha The time-step used to evolve non-cosmological quantities such
+ * as the artificial viscosity.
*/
__attribute__((always_inline)) INLINE static void hydro_prepare_force(
struct part* restrict p, struct xpart* restrict xp,
- const struct cosmology* cosmo) {
+ const struct cosmology* cosmo, const float dt_alpha) {
/* Initialise values that are used in the force loop */
p->flux.momentum[0] = 0.0f;
diff --git a/src/hydro/GizmoMFV/hydro.h b/src/hydro/GizmoMFV/hydro.h
index 98296a1a0d4fd5917c0f3cf4e492ac1c9916b360..24456b7bdf65acb516630d587e1319e58c96e2fe 100644
--- a/src/hydro/GizmoMFV/hydro.h
+++ b/src/hydro/GizmoMFV/hydro.h
@@ -466,17 +466,22 @@ __attribute__((always_inline)) INLINE static void hydro_end_gradient(
/**
* @brief Prepare a particle for the force calculation.
*
- * This function is called in the extra_ghost task to convert some quantities
- * coming from the gradient loop over neighbours into quantities ready to be
- * used in the force loop over neighbours.
+ * This function is called in the ghost task to convert some quantities coming
+ * from the density loop over neighbours into quantities ready to be used in the
+ * force loop over neighbours. Quantities are typically read from the density
+ * sub-structure and written to the force sub-structure.
+ * Examples of calculations done here include the calculation of viscosity term
+ * constants, thermal conduction terms, hydro conversions, etc.
*
* @param p The particle to act upon
* @param xp The extended particle data to act upon
* @param cosmo The current cosmological model.
+ * @param dt_alpha The time-step used to evolve non-cosmological quantities such
+ * as the artificial viscosity.
*/
__attribute__((always_inline)) INLINE static void hydro_prepare_force(
struct part* restrict p, struct xpart* restrict xp,
- const struct cosmology* cosmo) {
+ const struct cosmology* cosmo, const float dt_alpha) {
/* Initialise values that are used in the force loop */
p->gravity.mflux[0] = 0.0f;
diff --git a/src/hydro/Minimal/hydro.h b/src/hydro/Minimal/hydro.h
index acac81ecdf435af02a15f89a13d689b043f26f96..cf629814817064c109f7f016f81b6c621b087436 100644
--- a/src/hydro/Minimal/hydro.h
+++ b/src/hydro/Minimal/hydro.h
@@ -385,10 +385,12 @@ __attribute__((always_inline)) INLINE static void hydro_part_has_no_neighbours(
* @param p The particle to act upon
* @param xp The extended particle data to act upon
* @param cosmo The current cosmological model.
+ * @param dt_alpha The time-step used to evolve non-cosmological quantities such
+ * as the artificial viscosity.
*/
__attribute__((always_inline)) INLINE static void hydro_prepare_force(
struct part *restrict p, struct xpart *restrict xp,
- const struct cosmology *cosmo) {
+ const struct cosmology *cosmo, const float dt_alpha) {
/* Compute the pressure */
const float pressure = gas_pressure_from_internal_energy(p->rho, p->u);
diff --git a/src/hydro/Planetary/hydro.h b/src/hydro/Planetary/hydro.h
index b7cd16d3773c1ab538636d143d9488576a33ebb1..57025b17e106ae4b71f150d2c2d319e92752ec9e 100644
--- a/src/hydro/Planetary/hydro.h
+++ b/src/hydro/Planetary/hydro.h
@@ -393,10 +393,12 @@ __attribute__((always_inline)) INLINE static void hydro_part_has_no_neighbours(
* @param p The particle to act upon
* @param xp The extended particle data to act upon
* @param cosmo The current cosmological model.
+ * @param dt_alpha The time-step used to evolve non-cosmological quantities such
+ * as the artificial viscosity.
*/
__attribute__((always_inline)) INLINE static void hydro_prepare_force(
struct part *restrict p, struct xpart *restrict xp,
- const struct cosmology *cosmo) {
+ const struct cosmology *cosmo, const float dt_alpha) {
#ifdef PLANETARY_SPH_BALSARA
const float fac_mu = cosmo->a_factor_mu;
diff --git a/src/hydro/PressureEnergy/hydro.h b/src/hydro/PressureEnergy/hydro.h
index 32075481be7cadc08bad01fe13f4d9d3f5a24b0e..0ee25c3adbe8d3f46a461692f26ccccf0390b338 100644
--- a/src/hydro/PressureEnergy/hydro.h
+++ b/src/hydro/PressureEnergy/hydro.h
@@ -427,10 +427,12 @@ __attribute__((always_inline)) INLINE static void hydro_part_has_no_neighbours(
* @param p The particle to act upon
* @param xp The extended particle data to act upon
* @param cosmo The current cosmological model.
+ * @param dt_alpha The time-step used to evolve non-cosmological quantities such
+ * as the artificial viscosity.
*/
__attribute__((always_inline)) INLINE static void hydro_prepare_force(
struct part *restrict p, struct xpart *restrict xp,
- const struct cosmology *cosmo) {
+ const struct cosmology *cosmo, const float dt_alpha) {
const float fac_mu = cosmo->a_factor_mu;
diff --git a/src/hydro/PressureEntropy/hydro.h b/src/hydro/PressureEntropy/hydro.h
index 95608b5538be5fe46094209b12ec416582396431..a5c0c62c385a2304adb27ccbad4b7f6769d8b5d0 100644
--- a/src/hydro/PressureEntropy/hydro.h
+++ b/src/hydro/PressureEntropy/hydro.h
@@ -370,15 +370,22 @@ __attribute__((always_inline)) INLINE static void hydro_part_has_no_neighbours(
/**
* @brief Prepare a particle for the force calculation.
*
- * Computes viscosity term, conduction term and smoothing length gradient terms.
+ * This function is called in the ghost task to convert some quantities coming
+ * from the density loop over neighbours into quantities ready to be used in the
+ * force loop over neighbours. Quantities are typically read from the density
+ * sub-structure and written to the force sub-structure.
+ * Examples of calculations done here include the calculation of viscosity term
+ * constants, thermal conduction terms, hydro conversions, etc.
*
* @param p The particle to act upon
* @param xp The extended particle data to act upon
* @param cosmo The current cosmological model.
+ * @param dt_alpha The time-step used to evolve non-cosmological quantities such
+ * as the artificial viscosity.
*/
__attribute__((always_inline)) INLINE static void hydro_prepare_force(
struct part *restrict p, struct xpart *restrict xp,
- const struct cosmology *cosmo) {
+ const struct cosmology *cosmo, const float dt_alpha) {
const float fac_mu = cosmo->a_factor_mu;
diff --git a/src/hydro/Shadowswift/hydro.h b/src/hydro/Shadowswift/hydro.h
index 6b8046bac8210e6edd8c3bbbf5e8310e401e4c06..0715223850023be90294e5ccaa43c197c8eab2d4 100644
--- a/src/hydro/Shadowswift/hydro.h
+++ b/src/hydro/Shadowswift/hydro.h
@@ -283,22 +283,24 @@ __attribute__((always_inline)) INLINE static void hydro_part_has_no_neighbours(
}
/**
- * @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.
+ * @brief Prepare a particle for the force calculation.
*
- * 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.
+ * This function is called in the ghost task to convert some quantities coming
+ * from the density loop over neighbours into quantities ready to be used in the
+ * force loop over neighbours. Quantities are typically read from the density
+ * sub-structure and written to the force sub-structure.
+ * Examples of calculations done here include the calculation of viscosity term
+ * constants, thermal conduction terms, hydro conversions, etc.
*
- * @param p The particle to act upon.
- * @param xp The extended particle data to act upon.
+ * @param p The particle to act upon
+ * @param xp The extended particle data to act upon
+ * @param cosmo The current cosmological model.
+ * @param dt_alpha The time-step used to evolve non-cosmological quantities such
+ * as the artificial viscosity.
*/
__attribute__((always_inline)) INLINE static void hydro_prepare_force(
struct part* restrict p, struct xpart* restrict xp,
- const struct cosmology* cosmo) {
+ const struct cosmology* cosmo, const float dt_alpha) {
/* Initialize time step criterion variables */
p->timestepvars.vmax = 0.0f;
diff --git a/src/runner.c b/src/runner.c
index 0be6288cbcc0b77fbe9ba3128d820b82a8943480..828adc4185e2050fee2c48fa31b7af3ad7962f7e 100644
--- a/src/runner.c
+++ b/src/runner.c
@@ -642,6 +642,8 @@ void runner_do_extra_ghost(struct runner *r, struct cell *c, int timer) {
struct xpart *restrict xparts = c->xparts;
const int count = c->count;
const struct engine *e = r->e;
+ const integertime_t ti_end = e->ti_current;
+ const double time_base = e->time_base;
const struct cosmology *cosmo = e->cosmology;
TIMER_TIC;
@@ -663,6 +665,16 @@ void runner_do_extra_ghost(struct runner *r, struct cell *c, int timer) {
struct xpart *restrict xp = &xparts[i];
if (part_is_active(p, e)) {
+ /* Calculate the time-step for passing to hydro_prepare_force, used for
+ * the evolution of alpha factors (i.e. those involved in the artificial
+ * viscosity and thermal conduction terms) */
+ double dt_alpha;
+ if (with_cosmology) {
+ const integertime_t ti_step = get_integer_timestep(p->time_bin);
+ dt_alpha = cosmology_get_delta_time(cosmo, ti_end - ti_step, ti_end);
+ } else {
+ dt_alpha = get_timestep(p->time_bin, time_base);
+ }
/* Finish the gradient calculation */
hydro_end_gradient(p);
@@ -670,7 +682,7 @@ void runner_do_extra_ghost(struct runner *r, struct cell *c, int timer) {
/* As of here, particle force variables will be set. */
/* Compute variables required for the force loop */
- hydro_prepare_force(p, xp, cosmo);
+ hydro_prepare_force(p, xp, cosmo, dt_alpha);
/* The particle force values are now set. Do _NOT_
try to read any particle density variables! */
@@ -705,10 +717,13 @@ void runner_do_ghost(struct runner *r, struct cell *c, int timer) {
const struct hydro_space *hs = &s->hs;
const struct cosmology *cosmo = e->cosmology;
const struct chemistry_global_data *chemistry = e->chemistry;
+ const double time_base = e->time_base;
+ const integertime_t ti_end = e->ti_current;
const float hydro_h_max = e->hydro_properties->h_max;
const float eps = e->hydro_properties->h_tolerance;
const float hydro_eta_dim =
pow_dimension(e->hydro_properties->eta_neighbours);
+ const int with_cosmology = (e->policy & engine_policy_cosmology);
const int max_smoothing_iter = e->hydro_properties->max_smoothing_iterations;
int redo = 0, count = 0;
@@ -759,6 +774,17 @@ void runner_do_ghost(struct runner *r, struct cell *c, int timer) {
float h_new;
int has_no_neighbours = 0;
+ /* Calculate the time-step for passing to hydro_prepare_force, used for
+ * the evolution of alpha factors (i.e. those involved in the artificial
+ * viscosity and thermal conduction terms) */
+ double dt_alpha;
+ if (with_cosmology) {
+ const integertime_t ti_step = get_integer_timestep(p->time_bin);
+ dt_alpha = cosmology_get_delta_time(cosmo, ti_end - ti_step, ti_end);
+ } else {
+ dt_alpha = get_timestep(p->time_bin, time_base);
+ }
+
if (p->density.wcount == 0.f) { /* No neighbours case */
/* Flag that there were no neighbours */
@@ -784,9 +810,9 @@ void runner_do_ghost(struct runner *r, struct cell *c, int timer) {
/* Skip if h is already h_max and we don't have enough neighbours */
if ((p->h >= hydro_h_max) && (f < 0.f)) {
- /* We have a particle whose smoothing length is already set (wants to
- * be larger but has already hit the maximum). So, just tidy up as if
- * the smoothing length had converged correctly */
+ /* We have a particle whose smoothing length is already set (wants
+ * to be larger but has already hit the maximum). So, just tidy up
+ * as if the smoothing length had converged correctly */
#ifdef EXTRA_HYDRO_LOOP
@@ -806,7 +832,7 @@ void runner_do_ghost(struct runner *r, struct cell *c, int timer) {
/* As of here, particle force variables will be set. */
/* Compute variables required for the force loop */
- hydro_prepare_force(p, xp, cosmo);
+ hydro_prepare_force(p, xp, cosmo, dt_alpha);
/* The particle force values are now set. Do _NOT_
try to read any particle density variables! */
@@ -888,7 +914,7 @@ void runner_do_ghost(struct runner *r, struct cell *c, int timer) {
/* As of here, particle force variables will be set. */
/* Compute variables required for the force loop */
- hydro_prepare_force(p, xp, cosmo);
+ hydro_prepare_force(p, xp, cosmo, dt_alpha);
/* The particle force values are now set. Do _NOT_
try to read any particle density variables! */