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Old 04-10-2008, 12:42 AM   #28 (permalink)
Join Date: Dec 2007
Location: Bay Area
Posts: 1,151

The Miata - '01 Mazda MX-5 Miata
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Originally Posted by SteveP View Post

I checked out your build thread for the HPV fairing (very cool project, BTW) and noticed that you claimed a Reynolds number of 184. Not 184,000 but 184. Unless I'm totally misunderstanding what you're reporting, that really doesn't seem reasonable--using a characteristic length of 60" and a speed of 30 mph in 20C air I get a Re of 1.4E6. Just to make sure, I did a little looking around the net and even the Re for a bicycle helmet is 1e5.

What am I missing? I ask, because if the Re is really out of line with cars, then your ride height experiment might not be transferable to a car.

I'll have to see if I can pull the characteristic length out of the model.... It's not like a chord of an airfoil - there's a lot of compound curves in there (and I really don't want to start hand calculating that) :/ But I'll double check <-- mind you, runs I do personally are with software that doesn't give Re# data

I'm not looking for transferability - but there was a blanket statement made that applies to vehicles with streamlined undersides.

All that aside - we should have tuft testing data next week So if there's some obvious flow issues, we'll see them
Cars have not created a new problem. They merely made more urgent the necessity to solve existing ones.
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