From 1a8c39aa96e35a15a4b96d7d53431c6fb335c1b3 Mon Sep 17 00:00:00 2001
From: Matthieu Schaller <schaller@strw.leidenuniv.nl>
Date: Sat, 8 Jun 2019 14:45:55 +0200
Subject: [PATCH] Make the minimal smoothing length used by SWIFT to match the
Gadget definition of the kernel support being a fixed fraction of the
softening kernel support and not use 'h' directly.
---
src/hydro_properties.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/src/hydro_properties.c b/src/hydro_properties.c
index 604a61f1a7..0082546ce1 100644
--- a/src/hydro_properties.c
+++ b/src/hydro_properties.c
@@ -332,8 +332,13 @@ void hydro_props_init_no_hydro(struct hydro_props *p) {
void hydro_props_update(struct hydro_props *p, const struct gravity_props *gp,
const struct cosmology *cosmo) {
- /* Update the minimal allowed smoothing length */
- p->h_min = p->h_min_ratio * gp->epsilon_cur;
+ /* Update the minimal allowed smoothing length
+ *
+ * We follow Gadget here and demand that the kernel support (h * gamma)
+ * is a fixed fraction of the radius at which the softened forces
+ * recover a Newtonian behaviour (i.e. 2.8 * Plummer equivalent softening
+ * in the case of a cubic spline kernel). */
+ p->h_min = p->h_min_ratio * gp->epsilon_cur / kernel_gamma;
}
/**
--
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