← All workIndependent study · 2026

Front wing in ground effect

An F1 front wing runs centimetres off the road, where ground effect can add downforce or suddenly take it away. I mapped how downforce, drag and the flow change with ride height for a single wing element, and turned that into a ride-height recommendation.

Sweep: 11 ride heights, 250 → 15 mm
Peak: +47% downforce at a 44 mm gap
Then: −16% downforce, 4.5× drag by 15 mm
Tools: ANSYS Fluent · 2D RANS, k-ω SST

ASet-up

Validate first, then sweep.

Wing	NACA 4412, inverted, chord 250 mm, 4° incidence
Flow	50 m/s, Re = 8.6 × 10⁵, moving ground
Model	Steady RANS, k-ω SST, coupled, 2nd order
Mesh	107 000–148 000 cells, 25 prism layers
Sweep	h/c 1.0 → 0.06, 11 cases, residuals 1e-5

Validation, h/c 1.0	CFD	Reference
Downforce C_L	0.902	0.875–0.915
Drag C_D	0.0152	0.0135 (turbulent)
Wall y+ on wing	≤ 1.8	≈ 1 for SST

Close-up of the CFD mesh with boundary-layer cells wrapped around the wing and along the road. — Mesh at h/c 0.20: quad boundary layer wrapped round the wing and along the road, fanned at the sharp trailing edge. Reference values from NeuralFoil at the same Reynolds number and incidence.

BResult

Downforce climbs, plateaus, then falls.

Two charts: downforce coefficient against ride height, peaking near h/c 0.175, and efficiency against ride height. — Downforce rises 47% as the gap closes to 44 mm, plateaus, then falls 16% by 15 mm while drag climbs 4.5×.

Velocity contours at 250 mm ride height. — h/c 1.0 (250 mm): attached flow, thin wake. C_L 0.902.

Velocity contours at 50 mm ride height. — h/c 0.20 (50 mm): gap flow accelerates; a small separated zone forms at the tail. C_L 1.319.

Velocity contours at 15 mm ride height with a large separated wake. — h/c 0.06 (15 mm): gap air reaches 99 m/s, but the rear 43% of the underside separates. C_L 1.113.

Why it stalls

Closing the gap speeds up the air under the wing, which adds suction. But the air then has to slow back down before the trailing edge, and the tighter the gap, the harder that recovery. Below about 44 mm the separated zone grows faster than the gap suction, so downforce falls and drag climbs.

h/c	Separates at	C_L	C_L / C_D
1.00	none	0.902	59.4
0.20	82% chord	1.319	43.7
0.06	57% chord	1.113	16.4

CRecommendation

Set the wing at 50 mm, not at the peak.

At h/c 0.20 the wing makes 99.5% of maximum downforce with 11% better efficiency, and keeps 6 mm of margin before heave or braking pitch push it onto the falling side, where downforce drops as the car sinks. That loop is the same physics behind porpoising.

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