The milestone of computing the drag of car by solving the Navier-Stokes equations was passed in 2011 with the work reported in Adaptive Simulation of Turbulent Flow Past a Full Car Model, by N. Jansson, J. Hoffman and M. Nazarov: With about 10 million mesh points a C_D of 0.38 was computed, to be compared with measured 0.36.

A crucial feature of the computation is the use of a slip boundary condition as a model of small skin friction instead of the dictate by Prandtl to use no-slip causing thin boundary layers demanding quadrillions of mesh points thus making computational simulation of slightly viscous turbulent flow impossible. With slip it is possible and a wealth of applications are ready for computational harvest, see for example The Secret of Flight.

Wind tunnels for testing cars can now be dismantled and replaced by adaptive computation with major reductions in cost and lead time. Some snapshots from the article:

## Vorticity of Primal Navier-Stokes/slip Solution

## Drag Coefficient

## Dual Solution as Sensitivity to Adaptivity

## Mesh Refinement and Flow Velocity

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## Anders Logg

Impressive simulation! But what happens beyond 1e7? The plot of the drag coefficient does not seem to indicate any kind of convergence and seems to stop by chance at the correct value. Maybe there are more data points missing in the plot?