WindSim

WindSim is a browser-native aerodynamics project with two distinct surfaces:

• sandbox.html: the working reduced-order 3D wind sandbox
• cfd.html: the Phase D CFD laboratory workbench with a deterministic LBM solver stack and post-processing visualization

The launcher at index.html routes between them.

Source Of Truth

docs/CFD_MASTER_BLUEPRINT.md → CFD implementation phases docs/WINDSIM_ENGINEERING_PLAN.md → full system architecture and requirements

That blueprint is the active plan for the CFD side of the repo. The core rule is simple: the UI must not imply solved physics that the code does not actually compute.

Current State

Sandbox

The sandbox is the mature part of the project. It currently provides:

• reduced-order rigid-body aerodynamics with drag, lift, Magnus force, rotation, contact, and telemetry
• experiment workflows such as mounted mode, playback, sweeps, saved comparisons, and flow-probe slices
• a modular split across js/windsim-app.js, js/windsim-physics.js, js/windsim-ui.js, js/windsim-scene.js, js/windsim-workflows.js, js/windsim-textures.js, and js/windsim-models.js
• multiple solver registrations through js/windsim-solvers.js

CFD Lab

The CFD surface is currently in Phase D (Post-Processing & Visualization).

What is real today:

• WebGPU capability detection and hardware-tier routing
• A complete workflow guiding you through geometry, domain, boundary, solver setup, execution, and inspection
• A Three.js viewport rendering domain boundary, voxelized mesh geometry, slices, and streamlines
• A deterministic D3Q19 Lattice Boltzmann Method (LBM) solver core running on the CPU
• Drag, lift, and side force calculations with dynamic calibration and capability advising
• Session persistence (state saving and recovery) via IndexedDB
• Live post-processing visualization (pressure/velocity slice maps, streamline seeding, color mapping)

What is not real yet:

• Full WebGPU-based solver computing layer (currently using CPU reference kernel; WebGPU is used for visualization only)

Experimental Solver Work

js/windsim-cfd.js contains an experimental 2D grid-based solver path for the sandbox side. It is transitional work, not the final CFD lab backend, and it does not yet replace the full reduced-order pipeline with a true coupled 3D solver.

Repo Layout

• index.html Launcher that routes to the sandbox or the CFD lab.
• sandbox.html Working reduced-order simulator surface.
• cfd.html Phase D CFD workbench.
• css/windsim-entry.css Entry and landing system styling for the sandbox experience.
• css/cfd-entry.css CFD lab styling.
• js/windsim-*.js Sandbox modules.
• js/cfd-*.js CFD workbench modules (geometry, coefficients, solver, observability, post-processing, regime, and engine).
• js/windsim-cfd.js Experimental sandbox-side grid solver work.
• docs/CFD_MASTER_BLUEPRINT.md Active CFD implementation blueprint.
• docs/CHANGELOG.md High-level change history.

Honesty Rules

• The sandbox can use reduced-order and heuristic models, but it must label them honestly.
• The CFD lab must not show fake solved outputs.
• If a feature is not wired to real computation yet, it should stay locked, blank, or explicitly marked as shell-only.