From: mmorris <michael.morris@adelaide.edu.au>
  To  : Allen Minton <minton@helix.nih.gov>
  Date: Fri, 07 Sep 2001 10:04:24 +0930

Re: hydrodynamic question

Hi Allen,

If you van Holde, Physical Biochemistry an equation is listed for
calculating f for a "Long rod" (page 81, 1st Ed.) or f/fo for a long rod
(page 95, 2nd Ed.). Sorry, no reference is given and I am not sure if
the word "Long" has any significance. 

Can anyone advise me on this, since I have been curious to know?

Yours, Michael

Allen Minton wrote:
> 
> Hi gang -
> 
> A question for the hydrodynamics experts:
> 
> We can calculate the frictional coefficient for an ellipsoid of rotation
> (prolate or oblate) using the well-known Perrin equation.   How can we
> calculate the frictional coefficient for a cylindrical rod of arbitrary
> length/diameter ratio?
> 
> I am guessing that the bead model might work, but it's not clear how one
> would best represent the rod as an array of beads.  I doubt that one could
> realistically represent the rod as a simple linear array of beads with a
> diameter equal to a bead diameter and a length equal to the number of beads
> times the bead diameter, but perhaps some experienced person could set me
> right on that point.
> 
> Does anyone know of an analytical solution to the rod problem, along the
> lines of the Perrin equation?
> 
> Allen Minton
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