Dust above or below?

Above wins if the particle’s final y-coordinate is greater than or equal to the previous particle’s exit y-coordinate. Below wins if it is lower. A winning share pays 1 gold; a losing share pays 0. The dashed line is fixed throughout the round.

Each round ends when the particle reaches the outlet, usually in around two minutes. A consistent playback speed preserves differences in transit time. Physical simulation time is shown below the tunnel. New rounds start automatically. All players see the same experiment.

Use the downloadable NASA sharp-trailing-edge NACA 0012 geometry and the public physical conditions. Coordinates use chord units, x points right, and y points up. The aerofoil is pitched nose-up by 20° about its quarter-chord.

Incompressible, two-dimensional, unsteady flow; no-slip aerofoil, uniform inlet, open upper/lower boundaries, and a pressure outlet. Particle inertia, gravity, and particle feedback are neglected.

These are precomputed OpenFOAM velocity fields and particle trajectories, not a random animation. The hosted service keeps the replay library private and sends only observed motion and the current flow field. Small background dust tracers are advected through that observed field; their fading trails mimic a long-exposure wind-tunnel photograph. Only the gold particle determines the result. The finite library repeats; this is an educational prototype.

NACA 0012 is a widely studied validation geometry. This exploratory 2D, low-Reynolds-number simulation is not a validated prediction of real three-dimensional stall. The geometry reference uses different flow conditions. Our numerical solver configuration, mesh, and initial wake state remain private.

NASA geometry reference ↗ · Low-Reynolds-number wake research ↗

Dataset: connecting…