[PSUBS-MAILIST] Buoyancy dynamics

[via Personal_Submersibles]

Complicated. Just watch the bubbles. 60 feet per minute, give or take.Vance

-----Original Message-----
From: River Dolfi via Personal_Submersibles <personal_submersibles at psubs.org>
To: via Personal_Submersibles <personal_submersibles at psubs.org>
Sent: Sun, Aug 16, 2020 12:10 pm
Subject: Re: [PSUBS-MAILIST] Buoyancy dynamics

Jon, are you asking about how to correlate buoyancy condition with vertical speed through the water? IE "If I drain 50lb from the VBT and make myself 50lb positively buoyant, how long will it take me to reach the surface 600ft up?"
You would have to know the drag coefficient and a reference area of the sub in question in the up and down direction. Usually that kind of number is determined with fancy CFD or wind tunnel testing. I've got a couple data points about buoyancy vs vertical speed that I could crunch to get an approximate drag coefficient appropriate for small submersibles, then you could calculate the speed for any sub of a given cross sectional area.
Thanks,
-River J. Dolfi
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