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🌌 Welcome to the GRANITE Wiki

GRANITE (General‑Relativistic Adaptive N‑body Integrated Tool for Extreme Astrophysics) is a high‑performance, open‑source numerical relativity engine designed to simulate the most violent events in the universe: the simultaneous inspiral, tidal disruption, and merger of multiple supermassive black holes in the presence of massive stars, magnetic fields, radiation, and neutrino microphysics.

What makes GRANITE different?

Unlike traditional numerical relativity codes that focus on binary black hole or binary neutron star mergers, GRANITE is built from the ground up for N‑body supermassive black hole coalescence (N ≥ 3) with full physics:

• CCZ4 spacetime evolution – 22 evolved variables, 4th‑order finite differences, moving‑puncture gauge, Kreiss–Oliger dissipation.
• GRMHD with advanced Riemann solvers – HLLE and HLLD (Miyoshi & Kusano 2005), MP5/PPM/PLM reconstruction, constrained transport (∇·B = 0).
• Multi‑physics matter – tabulated nuclear EOS, M1 grey radiation transport, hybrid neutrino leakage + moments.
• Block‑structured AMR – Berger–Oliger subcycling, gradient‑based tagging, tracking spheres for moving horizons (full multi‑level AMR is under active development).
• Post‑processing suite – Ψ₄ gravitational‑wave extraction, spin‑weighted spherical harmonics, recoil velocity, Blandford–Znajek jet power, and EM light curves.
• HPC ready – MPI + OpenMP + HDF5 parallel I/O. GPU backends (CUDA/HIP) are on the roadmap.

Current status

• Latest stable release: v0.6.5 (“The Stability Update”)
• Test suite: 92 unit tests, 100% pass rate (GoogleTest)
• Validated benchmarks: single_puncture (Schwarzschild stability), B2_eq (equal‑mass binary black hole merger), gauge_wave (CCZ4 code validation)
• Production‑grade components: CCZ4 core, GRMHD Valencia formulation, HLLD+CT, tabulated EOS, horizon finder, Python analysis tools.

📚 Quick links

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📖 Documentation — Start Here

If you want to...	Go to
Install GRANITE	Installation Guide
Understand the engine architecture	Architecture Overview
Configure a simulation	Parameter Reference
Debug a failing simulation	Simulation Health & Debugging
Understand the physics equations	Physics Formulations
See benchmark results	Benchmarks & Validation
Deploy on HPC	HPC Deployment
Contribute code	Developer Guide
See what bugs have been fixed	Known Fixed Bugs
Understand initial data options	Initial Data
Learn about AMR design	AMR Design
Understand GW extraction	GW Extraction
See what's coming next	Roadmap
Get answers to common questions	FAQ
See the scientific context	Scientific Context
Navigate all documents	Documentation Index
Version history	CHANGELOG Summary
VORTEX N-Body Interactive WebGL Sim	VORTEX Engine

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Getting started

1. Follow the Installation Guide (Linux / WSL2 only).
2. Run the health check: python3 scripts/health_check.py
3. Launch the single‑puncture benchmark: python3 scripts/run_granite.py run --benchmark single_puncture You can also run the simulation on Diagnostics Mode: python3 scripts/sim_tracker.py build/bin/granite_main benchmarks/single_puncture/params.yaml
4. Explore the dev_benchmark.py And sim_tracker.py live dashboard for constraint monitoring, NaN forensics, and phase classification.

Follow these steps for a Quick Start:

🚀 Quick Start

git clone https://github.com/LiranOG/Granite.git && cd Granite

# Install dependencies (Ubuntu/WSL2)
sudo apt update && sudo apt install -y build-essential cmake libhdf5-dev libopenmpi-dev libyaml-cpp-dev

# Build
python3 scripts/run_granite.py build --release

# Pre-flight check
python3 scripts/health_check.py

# Run single-puncture benchmark
python3 scripts/run_granite.py run --benchmark single_puncture

# Run BBH benchmark (~99 min)
python3 scripts/run_granite.py run --benchmark B2_eq

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🤝 Contributing & Partnership

GRANITE welcomes contributions from the scientific and open-source communities. See Developer Guide and .github/CONTRIBUTING.md.

For institutional partnership, HPC allocations, or academic collaboration: open a GitHub Issue tagged [partnership].

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"Simulate the unimaginable."
GRANITE v0.6.5 — April 10, 2026 — LiranOG