Re: laminar flow and shear forces

Dear dantimatter:

On Mar 28, 8:55 am, "dantimatter" <dantimat...@xxxxxxxxx> wrote:
Hello all,

I'm studying bacteria in a microfluidic channel, and I'm
trying to understand the relevant fluid mechanics.
Specifically, I'd like to know two things: 1) what a
laminar flow profile looks like,

An inverted parabola, with the area under the curve = the volume of
flow moved in a unit time, and zero at the wall.

and 2) if the bacteria are attached to the sides of the
channel, what are the shear forces that the bacteria
are feeling?

A laminar profile has the lowest wall shear stress, and has no time-
varying component that can "fatigue" attachment methods to failure.

If the shear forces are too high, then there's a possibility
that a stress response will be induced in the bacteria,
and that would be bad.

Any help would be appreciated.

The flow rate will be the only control you have to limit the flow
rate. Laminar flow is already the most "quiescent" you can achieve,
short of no motion at all.

Now you could form small pockets outside the tube wall, and let the
bacteria inhabit the even quieter pockets. Vorticity should be
small...

David A. Smith

.

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