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The annoying thing with CFD with analyzing viscous phenomena is the question of reproducibility. Flow structures in this regime (low Re, that is low speed and small length scales) are notoriously sensitive to surface defects, e.g. the hairs being analyzed. A CFD sim will show nearly the same results for a given problem, and current CFD lacks the fidelity to really model tiny turbulent features at these scales as well as the necessary fine surface definition. Experimental results may show drastically different results depending on the minute upstream flow variations, and surface quality: in this case, legs with hair/sweat/dust/oils could all trip the boundary layer to varying degrees. Stories abound of clumsy wind tunnel technicians who left skin grease on a wing model for a low-speed test and neglected to polish it with a rag...


Yeah.

Faster talks about a certain dimpled TT helmet[1], and how it would probably work really well if your head rotated continuously while you rode.

[1] The book doesn't name which one, but this is the only dimpled TT helmet I know of: http://www.louisgarneau.com/in-en/product/826916/1405156/Vie...




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