Pravash

Pravash (Sanskrit: प्रवास — journey, flow) — fluid dynamics simulation for AGNOS

Particle-based and grid-based fluid simulation. SPH for real-time effects, Euler/Navier-Stokes for accurate simulation, shallow water for surface waves, multi-phase for immiscible fluids, viscoelastic for honey/lava, heat transfer and combustion for fire effects. Built on hisab for math foundations.

Non-linear SWE, HLL Riemann, Green-Naghdi dispersion, sediment transport, multi-phase SPH, DFSPH, MPM, VoF, phase-field, Oldroyd-B viscoelasticity, non-Newtonian viscosity, heat conduction, combustion, foam/spray/bubble, APIC, MAC grid, multigrid, k-epsilon turbulence, autodiff, Rayon parallelism, GPU-agnostic compute interface — zero unsafe, 290+ tests.

Installation

[dependencies]
pravash = "1.1"

Default features: sph, grid, shallow.

Optional: buoyancy, vortex, coupling, compute, parallel, ai, logging.

MSRV: 1.89 (Rust edition 2024).

Features

Feature	Default	Description
sph	yes	Smoothed Particle Hydrodynamics — particle-based fluids
grid	yes	Euler/Navier-Stokes grid-based solver
shallow	yes	Non-linear shallow water equations — 2D surface waves
buoyancy	no	Buoyancy, drag, Reynolds number, flow regime
vortex	no	Vorticity, Lamb-Oseen/Rankine vortices, enstrophy, Kolmogorov scale
coupling	no	Fluid-body interaction, FLIP/PIC hybrid, level set, added mass
compute	no	GPU-agnostic ComputeBackend trait, packed f32 buffers
parallel	no	Rayon parallelism for SPH and grid operations
ai	no	Daimon/hoosh integration (network deps)
logging	no	Structured logging + chrome://tracing profiling via PRAVASH_LOG
full	--	Enables all features

Quick Start

use pravash::sph::{SphSolver, create_particle_block, total_kinetic_energy};
use pravash::common::{FluidConfig, FluidMaterial};

let mut particles = create_particle_block([0.2, 0.5], [0.3, 0.3], 0.02, 0.001);
let config = FluidConfig::water_2d();
let mut solver = SphSolver::new();

for _ in 0..100 {
    solver.step(&mut particles, &config, FluidMaterial::WATER.viscosity).unwrap();
}

println!("KE: {}", total_kinetic_energy(&particles));

Modules

Module	Description
sph	SPH solver with spatial hash, PCISPH, DFSPH, Wendland/Delta-SPH kernels, adaptive timestep, multi-phase, viscoelastic (Oldroyd-B), non-Newtonian, implicit viscosity, heat/combustion, particle splitting/merging, foam/spray/bubble, MLS correction
grid	Navier-Stokes: MAC grid, semi-Lagrangian + MacCormack + BFECC advection, multigrid/DST/GS pressure, k-epsilon turbulence, Smagorinsky SGS, ghost fluid, periodic BCs. Rayon-parallelized
shallow	Non-linear SWE, HLL Riemann, Manning friction, wetting/drying, wave breaking, Green-Naghdi dispersion, Boussinesq, sediment transport, well-balanced terrain-following
mpm	Material Point Method — neo-Hookean, fluid, Drucker-Prager constitutive models
vof	Volume of Fluid — free surface tracking with donor-acceptor advection
phase_field	Allen-Cahn phase-field interface tracking with advection and double-well relaxation
buoyancy	Archimedes buoyancy, drag force, terminal velocity, Reynolds number, flow regime classification
vortex	Vorticity, Lamb-Oseen/Rankine vortex models, enstrophy, Kolmogorov microscale
coupling	RigidBody interaction (sphere/box SDF), FLIP/PIC/APIC hybrid, narrow-band FLIP, particle-level set, added mass, field drag
compute	GPU-agnostic ComputeBackend trait, NeuralCorrector, KernelDerivatives with autodiff, PackedParticles f32 buffers
common	FluidParticle (phase, temperature, fuel, conformation tensor), FluidMaterial, FluidConfig, ParticleSoa (SOA), ParticleArena (memory pool)

Examples

Example	Features	Description
basic_fluid	sph	SPH dam break with SphSolver, kinetic energy tracking
shallow_water	shallow	Shallow water splash with Manning friction
multiphase	sph	Water-oil two-phase simulation with interface tension

Run an example:

cargo run --example basic_fluid --features sph
cargo run --example shallow_water --features shallow
cargo run --example multiphase --features sph

Architecture

pravash (this crate)
  +-- hisab (math: vectors, spatial hash, FFT/DST, PDE solvers)

Consumer Crates

Crate	Usage
kiran	Water, smoke, fire effects
joshua	Fluid simulation
impetus	Fluid-body interaction

Documentation

• Migration Guide — breaking changes from 0.24.x
• Roadmap — upcoming features
• Contributing — workflow, code style, testing requirements
• Security Policy — reporting, supported versions

Building

cargo build --all-features
cargo test --all-features

License

GPL-3.0 — see LICENSE.