Overview
The wind branch of the Computational Acoustic Architecture work. Where the fountains use water, this uses moving air: Aeolian harps, organ-pipe arrays, Helmholtz resonator banks, vortex towers, edge-tone generators. You give it a wind speed and a target color of noise, and it sizes the structure to produce that sound -; with the flow physics modeled rather than guessed.
Background
Wind is a harder instrument to tune than water. Its speed varies, it's turbulent, and the sound comes from a handful of distinct mechanisms that each behave differently as the wind picks up. The point of the model is to make those mechanisms predictable enough to design around -; so a tower hums the note you intended across a realistic range of breezes, not just on a calm afternoon.
How It Works
The toolkit comes in three tiers: a simplified 2D flow model, a full 3D CFD pass, and a library of complex architectural geometries. The core acoustic mechanisms each have a model:
- Vortex shedding -; the Strouhal relation sets the tone behind a bluff body, with the Strouhal number itself a function of Reynolds number.
- Helmholtz resonance -; resonator cavities with a wind-tuned end correction.
- Edge tones -; jet-edge interaction across a nozzle gap.
- Turbulence -; the Kolmogorov −5/3 inertial-range slope contributes the broadband hiss.
The workhorse is vortex shedding -; the frequency a cylinder or tower sings at as air peels off it:
The 2D model solves potential flow around obstacles (Laplace's equation) and computes vorticity; the 3D model steps a vorticity-based Navier-Stokes approximation on a grid (dx ≈ 0.1 m, dt = 0.001 s) and produces full velocity and pressure fields. The complex-geometry library adds parametric wave facades, fractal canopies built by L-system recursion, twisted towers with helical channels, geodesic domes, and acoustic Mashrabiya screens. Ten structure types, six materials, and the same spectral-color optimization as the rest of the CAA suite.
Current Status
Archived. The 2D model, 3D CFD, and complex-geometry generators all run and export meshes; it lives inside the larger CAA project.
- Three modeling tiers from quick 2D to full 3D CFD.
- Ten wind-structure types with material-dependent spectra.
- Color optimization shared with the fountain and cityscape tools.