[ODE] Demo of buoyancy and ODE

[Jonathan Langridge]

From: Mattias Fagerlund <mattias@cambrianlabs.com>
Sent: Friday, February 07, 2003 4:10 PM
Subject: [ODE] Demo of buoyancy and ODE

...

> When a sphere is submerged under a flat body of water, the buoyancy
> force is directed straight up. When the body of water is tilted (due to
> wave action), the buoyancy force is effected - sphere heads for the
> surface, but I can't tell by how much :( Right now, I send the bobby
> heading for the surface the shortest possible route, and that's probably
> a fair aproximation at small water tilts, but is it correct?

It might be a fair approximation, but it's worth being aware that the only
things determining buoyancy direction are gravity and acceleration of the
system. I suspect the most significant influence on body floating as far as
waves are concerned is drag against the moving water, but I could well be
wrong. Just keep in mind that while the surface normal of the water may be a
good source for approximation, it doesn't have any real physical effect on
the buoyancy of submerged objects.

'Fraid I can't comment on the accuracy of the drag system you're using, but
I'm sure drag proportional to r^2 of sphere (surface area presented) times
v^2 would be good enough.

- Jon