As another ancient Chem E. I recall the mystical attribute of the Reynolds
number (Re) was that it is dimensionless. Yet, it predicted with great
accuracy, the flow regime one would encounter under specific sets of
conditions. Re<10 = stagnation; 10 < Re < 50 = creeping flow; 100 < Re
< 2,000 = laminar flow;
2,000 < Re = turbulent flow. I bow to Aeronautical Engineers (Jim?) at Re
> 5,000, somewhere beyond there is where things go supersonic. To we
simple Chem E's supersonic flow was the equivalent of "Here be Dragons" on
the maps of yore.
Bike related content: Turbulence is not a bad thing, energy expenditure drops (briefly) at Re 2,000 as flow shifts from laminar to turbulent. Most cycling aerodynamic aids that work simply decrease frontal area versus acheiving a more "slippery" Cd (coefficient of drag).
- Sid