This repository contains a multi-threaded Julia engine that simulates 3D stochastic Brownian molecular diffusion subjected to external aerodynamic wind drift.
Instead of traditional unit testing, this project implements a rigorous Verification & Validation (V&V) automation framework to mathematically audit the integrity of the stochastic simulation against established physics laws.
- Core Engine: Julia 1.10+ (leveraging native multi-threading for particle step updates)
- Graphics: CairoMakie.jl (used for vector-rendered data visualization)
- CLI Interface: ArgParse.jl (type-safe boundary input management)
Testing a stochastic Monte Carlo model requires statistical assertions rather than static expected outputs. Our pipeline executes three specific validation gates:
-
Numerical Sanity: Catches matrix dimension mismatches and actively scans arrays to ensure no floating-point operations return
NaNorInf. -
Kinematic Bounds: Verifies all particle vectors strictly initiate at the origin
$(0,0,0)$ and that consecutive spatial step delta limits are physically constrained. -
Statistical Invariance:
- Spatial Isotropy: Confirms uniform multi-axis thermal dispersion remains within a strict 15% variance ceiling.
-
Analytical Convergence: Dynamically cross-references empirical simulation outputs against the core Mean Squared Displacement (MSD) textbook solution:
$$MSD = 2dDt + (v_{wind} \cdot t)^2$$ If empirical data drifts past the analytical threshold, the pipeline automatically aborts the image rendering stage to prevent corrupted visual reports.
The engine functions as a decoupled CLI tool. You can pass arbitrary parameters or batch-loop scenarios via the shell wrapper.
# Setup
git clone [email protected]:PGComplexSystems/3dDiffusion.git
cd 3dDiffusion
# Syntax: ./run_pipeline.sh <STEPS> <PARTICLES> <WIND_SPEED>
./run_pipeline.sh 1600 300 2.5- Shift runtime arguments to a standalone
config.tomlparser. - Dynamically bake input metrics directly into CairoMakie plot headers.
- Set up a GitHub Actions workflow to run the V&V suite on push events.