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Wind Tunnel: Airfoil Lift & Drag (2D)

Q: Why does lift depend on circulation?

By the Kutta-Joukowski theorem, lift per unit span equals density times airspeed times circulation, where circulation is the flow adopted around the wing to satisfy the Kutta condition of smooth departure at the trailing edge.

Q: What happens past the stall angle?

Above roughly 16 degrees angle of attack, airflow separates from the upper surface and lift collapses while drag spikes; the simulation tapers lift and adds separation drag past that angle.

2D wind-tunnel lab: an analytic potential-flow airfoil (circle-plus-circulation, Kutta condition) streaming past a pitched wing section, with live lift, drag, Cl, Cd, Reynolds number and stall detection.

Physics & Mechanics2DAdvanced60 FPS📱 Mobile-adapted⇄ 3D version

This 2D companion streams an analytic potential-flow field — a uniform stream plus a doublet and a Kutta-condition vortex around the wing's generating circle — past a pitched airfoil, and reads off lift, drag, Cl, Cd, Reynolds number and stall state from the same closed-form Kutta–Joukowski relations used in thin-airfoil theory, instead of the arbitrary decorative sliders the original 3D scene used.

⚙ Under the hood

2D wind-tunnel lab with an exact circle-plus-circulation potential-flow field, thin-airfoil Cl/Cd relations, a stall taper past 16° angle of attack, and live lift, drag, Reynolds number and flow-state readouts.

wind tunnelairfoillift and dragangle of attackpotential flowreynolds number

2D · HTML5 Canvas 2D · 60 FPS target · runs fully client-side, no install

Why does lift depend on circulation?

By the Kutta–Joukowski theorem, lift per unit span equals ρ·V·Γ, where Γ is the circulation the flow adopts around the wing to satisfy the Kutta condition — smooth departure at the trailing edge. This simulation solves that circulation analytically for a pitched circle standing in for the wing's generating shape.

What happens past the stall angle?

Above roughly 16° angle of attack, real airflow separates from the upper surface and lift collapses while drag spikes. The model tapers the lift coefficient and adds separation drag past that angle, and the flow-state readout switches to "Stalled".

Why do the streamlines never touch the wing?

The velocity field is undefined inside the generating circle, so tracer particles are nudged along the surface instead of passing through it — the same no-penetration condition a real solid boundary enforces on the flow.