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Re: [Phys-L] BP or CE?

Phys-L@Phys-L.org writes:
On 12/22/2014 03:50 PM, Anthony Lapinski wrote:

What about these, which I sort of put into categories? Which effect
dominates?

perfume atomizer
Probably Bernoulli (dispensing); possibly also Coanda (atomizing)

blow between two hanging cans
I'd have to see the details. Could easily be done
in such a way that Coanda dominates, but that's not
the only possibility.

Just blowing between two aluminum cans hanging 5 cm apart.


shape of plane wing
Bernoulli can be applied, but is often very wrongly
applied. And you have to do a fair bit of work to
figure out the velocity field, and you can't begin
to apply Bernoulli until you've done that.

Also note that there are easier ways (Kutta Zhukovsky)
of figuring out the lift without bothering with Bernoulli.

spin on baseball pitch
Magnus effect. In some ways simpler, in some ways more
complicated than a wing. See previous item.

dimples on golf ball
Dimples affect drag by re-energizing the boundary layer.
Very tricky. Bernoulli applies to part of the problem,
and not other parts.

Wiffle ball
No comment. Never looked into it.

It's a plastic ball with holes in one half that makes it spin when thrown.

blow over paper
Usually Coanda

boomerang
Mostly just a wing, plus some angular momentum / precession

I though this was similar to an airplane wing since the tops and
bottoms are shaped similarly (flat on the bottom, more curved
on top).

vacuum cleaner and beach ball
Usually mostly Coanda

vertical Dyson fan and balloon
Haven't seen that one; possibly same as above.

This fan has a circular opening (and no blades) which blows
air along the outer edge

air blower and toilet paper roll
Haven't seen that one.

Done at many demo shows. There are probably videos online.

toy blow ball pipe
Haven't seen that one.

Like vacuum cleaner and beach ball

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