Wind over an Ahmed body, the standard car-aerodynamics test shape, here the AhmedML variant with a steep 61° rear slant. Threads of smoke from 65 nozzles ahead of the nose ride the simulated wind, coloured by speed. Over the roof and along the sides they stay smooth; at the tail the flow leaves the roof edge as behind a square-back car, and the threads slow to violet and tangle in the turbulent, low-pressure wake behind the base, where most of the drag comes from.
Fermioniq·8 October 2026
Figure 1
56 M cells, 4 mm at the body, wall-modelled LES · 3.6 h on an NVIDIA GH200 · rendered in Blender Cycles on the same GPU
How it was checked
Reference
Drag coefficient 0.231 over the last 8 s, against the AhmedML reference 0.238 (−3%)
Caveat
The smoke is traced through the velocity from every 2nd cell (8 mm), lightly smoothed, over 9 s of the run, played at 3/4 speed. The grid coarsens from 0.3 m behind the tail, so the far wake is less detailed.
More from the reel
Simulations written with Sofia, one per physics domain, each verified against a reference.
