APS March Meeting 2011
Volume 56, Number 1
Monday–Friday, March 21–25, 2011;
Dallas, Texas
Abstract: X9.00011 : Nonlinear dynamics of flagellar bundling
4:54 PM–5:06 PM
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Author:
Flagella are long thin appendages of microscopic organisms used
for propulsion in low-Reynolds environments. In many bacterial
species,
helical-shaped flagella driven by a molecular motor will bundle
up. This bundling process is poorly understood, and the exact
roles of
hydrodynamic interactions, helix elasticity, and mechanical
contact are unclear.
To investigate the bundling, we consider two flexible helices
next to each other, as well as several flagella attached to a
spherical body.
Each helix is modeled as several prolate spheroids connected by
springs. For HI, we consider the flagella to made up of point
forces, while
the finite size of the body is incorporated via Fax\'{e}n's laws.
Before flagella can bundle, they must synchronize.
Synchronization occurs fast relative to the bundling process. For
flagella next to each
other, the initial stage of bundling is governed by rotlet
interactions generated by the rotating helices. At longer times,
once bundling
has occurred, we find that a sharp distinction can be made
between ``tight'' and ``loose'' bundles, indicated by the local
distance between the flagella. As function of the anchor point
distance, a sharp transition from tight to loose is found when
starting from the completely unbundled state. Incremental steps
from stationary situations give multiple stationary for a single
anchor
distance. We show that the balance between elasticity and strong
non-linear hydrodynamic interactions is responsible for this
bifurcation
behavior.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2011.MAR.X9.11