Smoothed Particle Hydrodynamics

This example aims to reproduce Figure 9 from the paper "Implicit Surface Tension for SPH Fluid Simulation".

Interactive demo Interactive demo (cut)

Data

The data is genearted using the SPlisHSPlasH library which comes with the scene files used to generate the original figure:

SPHSimulate ../data/Scenes/SurfaceTension_WaterBell_JWL+23.json

Input contract

• particles: point-cloud from data/ParticleData_Fluid_0_10.vtk; velocity (vertex 3-channel vector).
• emitter: surface from data/emitter.msh; no pre-existing attributes required.

Reproduce and inspect

python ../render_gallery.py --check SPH
python ../render_gallery.py --artifacts SPH

Python · Manifest · Inspection · Canonical JSON · Validation

Code

#!/usr/bin/env python

import hakowan as hkw
import pyvista as pv
import numpy as np
from hakowan.spec import compile_expression

hkw.set_default_backend("mitsuba")

scene = hkw.SceneSettings(camera=hkw.PerspectiveCamera(eye=(0, 0, 3)))


def _recipe_data_id(_mesh):
    return "particles"


emitter = (
    hkw.layer("data/emitter.msh")
    .name("Emitter")
    .channel(material=hkw.material.RoughPlastic("Ivory"))
)

box_min = [-1.223, -0.5, -1.226]
box_max = [1.224, 4.0, 1.222]
roi_box = np.vstack([box_min, box_max])
for i in [10, 30, 60, 133]:
    # Lagrange's MSH writer does not retain vertex attributes on facet-free
    # point clouds. Load the original VTK particles so velocity reaches the
    # Norm transform and ScalarField colormap.
    particles = pv.read(f"data/ParticleData_Fluid_0_{i}.vtk")
    particle_frame = hkw.dataframe.to_dataframe(particles, roi_box=roi_box)
    fluid = (
        hkw.layer()
        .name(f"Fluid {i:03}")
        .data(particle_frame)
        .mark("Point")
        .channel(size=0.01)
        .material(
            "Principled",
            hkw.texture.ScalarField(
                "speed", domain=[0, 10], legend=False,
            ),
        )
    ).transform(hkw.transform.Norm("velocity", "speed"))
    all_particles = hkw.Figure(fluid + emitter, scene)
    if i == 10:
        RECIPE_FIGURE = all_particles
        RECIPE_INSPECTIONS = {
            "particles": particles,
            "emitter": "data/emitter.msh",
        }
        RECIPE_DATA_IDS = _recipe_data_id
    hkw.render(all_particles, filename=f"results/waterbell_{i:03}_all.webp")
    hkw.render(
        all_particles,
        backend="webgl",
        filename=f"results/waterbell_{i:03}_all.html",
    )

    filtered = fluid.transform(
        hkw.transform.Filter(condition=compile_expression("z <= 0"))
    )
    filtered_particles = hkw.Figure(filtered + emitter, scene)
    hkw.render(filtered_particles, filename=f"results/waterbell_{i:03}.webp")
    hkw.render(
        filtered_particles,
        backend="webgl",
        filename=f"results/waterbell_{i:03}.html",
    )