[aerohead]

*The surface friction coefficient is 0.003 (Hoerner)
*The surface area of an automobile is estimated @ 10-X frontal area (Hoerner)
*The surface friction drag of an automobile is 0.03 (Hoerner).
--------------------------------------------------------------------------
*Song,Zhang,Wang,and Hu's CAD model with smooth skin is Cd 0.3197.
*Without surface friction altogether,the drag is Cd 0.2897 (by subtraction)
*The surface drag component of the total drag is 9.38% (by calculation).
---------------------------------------------------------------------------
*Song et al. gives a non-smooth body drag reduction of 10.31%.
*The non-smooth drag is 9.9% lower than the car with zero skin friction.
*CFD results infer that the V-groove serrations have eliminated surface friction drag entirely,plus have cut into pressure drag as well.