From 28c96a8f30df3feb25df4202a3e627b09a9fc954 Mon Sep 17 00:00:00 2001
From: Matthieu Schaller <matthieu.schaller@durham.ac.uk>
Date: Thu, 28 Jan 2016 10:29:43 +0000
Subject: [PATCH] Corrected time-step evolution and better use of the fixdt
policy in the kick task
---
src/engine.c | 5 -----
src/runner.c | 46 +++++++++++++++++++++++++++-------------------
2 files changed, 27 insertions(+), 24 deletions(-)
diff --git a/src/engine.c b/src/engine.c
index 6d2921d802..206a924100 100644
--- a/src/engine.c
+++ b/src/engine.c
@@ -2169,11 +2169,6 @@ void engine_init(struct engine *e, struct space *s, float dt, int nr_threads,
/* Deal with timestep */
if(e->policy & engine_policy_fixdt) {
e->dt_min = e->dt_max;
-
- /* Put this timestep on the time line */
- float dt_timeline = e->timeEnd - e->timeBegin;
- while (e->dt_min < dt_timeline) dt_timeline /= 2.;
- e->dt_min = e->dt_max = dt_timeline;
}
/* Construct types for MPI communications */
diff --git a/src/runner.c b/src/runner.c
index b4b25586de..b80947fbdf 100644
--- a/src/runner.c
+++ b/src/runner.c
@@ -850,6 +850,7 @@ void runner_dokick(struct runner *r, struct cell *c, int timer) {
const float global_dt_min = r->e->dt_min, global_dt_max = r->e->dt_max;
const float t_current = r->e->time;
const int nr_parts = c->count;
+ const int fixdt = r->e->policy & engine_policy_fixdt;
int count = 0, updated;
float new_dt = 0.0f, new_dt_hydro = 0.0f, new_dt_grav = 0.0f,
@@ -883,7 +884,7 @@ void runner_dokick(struct runner *r, struct cell *c, int timer) {
x[0] = p->x[0], x[1] = p->x[1], x[2] = p->x[2];
/* If particle needs to be kicked */
- if (p->t_end <= t_current) {
+ if (p->t_end <= t_current || fixdt) {
/* First, finish the force loop */
p->force.h_dt *= p->h * 0.333333333f;
@@ -891,26 +892,34 @@ void runner_dokick(struct runner *r, struct cell *c, int timer) {
/* Recover the current timestep */
current_dt = p->t_end - p->t_begin;
- /* Compute the next timestep */
- new_dt_hydro = compute_timestep_hydro(p, xp);
- new_dt_grav = compute_timestep_grav(p, xp);
+ if( fixdt ) {
- new_dt = fminf(new_dt_hydro, new_dt_grav);
-
- /* Limit timestep increase */
- if (current_dt > 0.0f) new_dt = fminf(new_dt, 2.0f * current_dt);
+ /* Now we have a time step, proceed with the kick */
+ new_dt = global_dt_max;
+
+ } else {
- /* Limit timestep within the allowed range */
- new_dt = fminf(new_dt, global_dt_max);
- new_dt = fmaxf(new_dt, global_dt_min);
+ /* Compute the next timestep */
+ new_dt_hydro = compute_timestep_hydro(p, xp);
+ new_dt_grav = compute_timestep_grav(p, xp);
+
+ new_dt = fminf(new_dt_hydro, new_dt_grav);
+
+ /* Limit timestep increase */
+ if (current_dt > 0.0f) new_dt = fminf(new_dt, 2.0f * current_dt);
- /* Put this timestep on the time line */
- dt_timeline = dt_max_timeline;
- while (new_dt < dt_timeline) dt_timeline /= 2.;
-
- /* Now we have a time step, proceed with the kick */
- new_dt = dt_timeline;
+ /* Limit timestep within the allowed range */
+ new_dt = fminf(new_dt, global_dt_max);
+ new_dt = fmaxf(new_dt, global_dt_min);
+ /* Put this timestep on the time line */
+ dt_timeline = dt_max_timeline;
+ while (new_dt < dt_timeline) dt_timeline /= 2.;
+
+ /* Now we have a time step, proceed with the kick */
+ new_dt = dt_timeline;
+ }
+
/* Compute the time step for this kick */
t_start = 0.5f * (p->t_begin + p->t_end);
t_end = p->t_end + 0.5f * new_dt;
@@ -918,8 +927,7 @@ void runner_dokick(struct runner *r, struct cell *c, int timer) {
/* Move particle forward in time */
p->t_begin = p->t_end;
- p->t_end = p->t_begin + dt;
-
+ p->t_end = p->t_begin + new_dt;
/* Kick particles in momentum space */
xp->v_full[0] += p->a[0] * dt;
--
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