Adding a new SPH solver that is more physically accurate. See patch #29681

    http://projects.blender.org/tracker/index.php?func=detail&aid=29681&group_id=9&atid=127

The solver was mostly implemented by John Mansour at VPAC, with help from me and with funding from the AutoCRC. The SPH formulation is due to Gingold and Monaghan, and the smoothing kernel is due to Wendland.

This solver does not replace the old one; it is available as an option. Note that the new solver uses different units than the old one. The patch page has a couple of attachments that can be used to test the new solver, particularly sphclassical_dam_s0.01_grav.blend (ignore the earlier tests). The simulation in that file compares well with a physical experimental dam break; details in a paper by Changhong Hu and Makoto Sueyoshi, also referred to on that page.

1 files changed, 26 insertions, 1 deletions

diff --git a/source/blender/blenkernel/BKE_particle.h b/source/blender/blenkernel/BKE_particle.h
index bdaffef6818..f15ad296e4a 100644
--- a/source/blender/blenkernel/BKE_particle.h
+++ b/source/blender/blenkernel/BKE_particle.h
@@ -20,7 +20,9 @@
  *
  * The Original Code is: all of this file.
  *
- * Contributor(s): none yet.
+ * Adaptive time step
+ * Classical SPH
+ * Copyright 2011-2012 AutoCRC
  *
  * ***** END GPL LICENSE BLOCK *****
  */
@@ -58,6 +60,7 @@ struct RNG;
 struct SurfaceModifierData;
 struct BVHTreeRay;
 struct BVHTreeRayHit; 
+struct EdgeHash;
 
 #define PARTICLE_P              ParticleData * pa; int p
 #define LOOP_PARTICLES  for (p = 0, pa = psys->particles; p < psys->totpart; p++, pa++)
@@ -85,6 +88,24 @@ typedef struct ParticleSimulationData {
 	float courant_num;
 } ParticleSimulationData;
 
+typedef struct SPHData {
+	ParticleSystem *psys[10];
+	ParticleData *pa;
+	float mass;
+	struct EdgeHash *eh;
+	float *gravity;
+	float hfac;
+	/* Average distance to neighbours (other particles in the support domain),
+	   for calculating the Courant number (adaptive time step). */
+	int pass;
+	float element_size;
+	float flow[3];
+
+	/* Integrator callbacks. This allows different SPH implementations. */
+	void (*force_cb) (void *sphdata_v, ParticleKey *state, float *force, float *impulse);
+	void (*density_cb) (void *rangedata_v, int index, float squared_dist);
+} SPHData;
+
 typedef struct ParticleTexture {
 	float ivel;                           /* used in reset */
 	float time, life, exist, size;        /* used in init */
@@ -283,6 +304,10 @@ float psys_get_child_size(struct ParticleSystem *psys, struct ChildParticle *cpa
 void psys_get_particle_on_path(struct ParticleSimulationData *sim, int pa_num, struct ParticleKey *state, int vel);
 int psys_get_particle_state(struct ParticleSimulationData *sim, int p, struct ParticleKey *state, int always);
 
+void psys_sph_init(struct ParticleSimulationData *sim, struct SPHData *sphdata);
+void psys_sph_finalise(struct SPHData *sphdata);
+void psys_sph_density(struct BVHTree *tree, struct SPHData* data, float co[3], float vars[2]);
+
 /* for anim.c */
 void psys_get_dupli_texture(struct ParticleSystem *psys, struct ParticleSettings *part,
                             struct ParticleSystemModifierData *psmd, struct ParticleData *pa, struct ChildParticle *cpa,