[freebeard]

1) In order for the 'scale' flow to represent 'real flow' ( verisimilitude ) we need a minimum Reynolds number ( Rn ) of around 1,000,000, which is the 'supercritical Rn' for a fully developed turbulent boundary layer to exist.

I'm having trouble sorting out whether the viscosity of the fluid needs to be greater or less at smaller scales.

Gnats feel air like we do water, so maybe a less viscous fluid like ethanol?

Here's a CFD analysis of fifth-wheel teardrops: www.sciencedirect.com: Shape optimisation of teardrop trailers to minimise aerodynamic drag in articulated lorries