Len,
Here's a nifty graph regarding turbulence & thermal transfer:
...and here is the text to go with:
Quote:
Heat Transfer Enhancement
Convective heat transfer coefficient increases drastically when the flow becomes turbulent, due to effective mixing of different fluid layers in the flow. This behaviour is shown in following figure.So it is a common practice among designers to covert laminar flows into turbulent by introducing suitable vortex generators in the flow.
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Also another especially juicy bit:
...and the text to go with it:
Quote:
Drag reduction
Coefficient of drag around a body reduces by a huge amount when flow changes from laminar to turbulent.This phenomenon is shown in following figure.This is the reason why golf ball has got lot of dimples on it.This irregularities on surface of the ball will help in transforming laminar flow into turbulent and reduces drag, with low drag ball can travel more distance.
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The take away from this is that there is a small 'sweet spot' after turbulence is achieved, when there is a dramatic drop in fluid friction.
The big news is, at this sweet spot, there is both a 'drastic' increase in thermal transfer, and a 'huge amount' of fluid friction reduction.
Well worth working toward.
Fluid velocities beyond this sweet spot result in increasing fluid friction by the square of fluid velocity.
( above information from:
What is Turbulence ? ~ Learn Engineering )
Best,
-AC