overcome surface tension at microscopic dimensions

Dear All,

At low reynolds number system, surface tension is an important factor
affecting the fluid dynamics. So I have a question about bubbles, the
shrinking dimensions(low R), etc.

For example, if there is a box x=1cm, y=1mm, z=1cm, the volume will be
100 ul. If I fill 60ul of solution from a small hole at XY plane, the
box will be more than half full. The box is rotated around y axis, the
minuscus can cover the full surface of XZ plane 1cm*1cm. If I only
give it 40ul, the box will be less than half full so the surface of XZ
plane will not be fully covered when the box is roated along Y axis.
It will leave a round pattern uncovered in the middle. Agree?

But if I decrease Y thickness from 1mm to 100um (0.1mm), I believe the
surface tension will hold the solution so tight that the minuscus (at
the height of Z=6mm for 60ul of solution) will be very difficult to
move when the box is rotated. The surface tension pressure is given by
Laplace law P=2(gama)cos(theta)/r. gama is surface tension coeffecient
of the solution, theta is the contact angle and r is the radius of the
curvature of the interface.

I'd like to calculate the rotational force/speed needed (if
reasonable) to move the solution/air interface (ie. overcome surface
tension) as it did in the above example. But I don't have a clue. As
things change from macroscopic to miscroscopic, it gets complicated
and many surface effects have to be taken into consideration.

Thanks a lot if you can shine some light on it!

Frank

[Only registered users see links. ] (Frank) wrote in message news:<620b1276.0402192210.e889a69@posting.google.c om>...

Apparently, there is a problem with the system ...
one controls all?

This message was in my e-mail box with today's date.

************

Rejected for the obvious reason.

Sincerely,
Urs Schreiber,
moderator, s.p.r.

----- Original Message -----
From: "Mark Tarka" <[Only registered users see links. ]>
Newsgroups:
sci.physics.research,sci.physics.computational.flu id-dynamics,sci.physics,sci.
chem
To: <[Only registered users see links. ].org>
Sent: Saturday, February 28, 2004 10:20 PM
Subject: Re: overcome surface tension at microscopic dimensions


news:<620b1276.0402192210.e889a69@posting.google.c om>...

************


Mark (sci.physics.research cut from the distribution list :-)

"Frank" <[Only registered users see links. ]> wrote in message
news:[Only registered users see links. ] m...

Technicon's AutoAnalyzer systems made use of flowing liquids in tubing,
separated into small segments with air bubbles to control spreading. Lloyd
Snyder did probably the best theoretical treatments on this topic, based on
his HPLC expertise. You can try reaching him through [Only registered users see links. ].