Interdisciplinary Seminar in Nonlinear Science

Title: Dynamics of swimming bacteria and their fluid habitat
Speaker: john Kessler
Speaker Info: University of Arizona
Brief Description:
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Dynamics of swimming bacteria and their fluid habitat - -------- - ----------------------------------------------- Swimming bacteria ( Bacillus subtilis ) exhibit remarkably varied dynamics; new features arise as the concentration and total number of interacting individuals increases. Topics covered will include 1) the observed distribution of swimming velocities of individual cells, 2) binary interactions, 3) influence of bounding geometry on the velocity probability densities for speed and direction of swimming, 4) consumption/supply - driven bioconvection patterns, and 5) chaotic dynamics of populations at high volume fraction, where the trajectories of inert tracers include intermittent "trapping", long flights, and transport exponents reminiscent of the superdiffusion found in "2-d turbulence". Approaches to modelling will be introduced, for: pair interactions, bioconvection, the origin of coherent domains leading to "2-d turbulence", high collective velocities when volume fractions approach close-packed, and the anomaly of a semblance of turbulence at nominally low Reynolds number.
Date: Friday, February 23, 2001
Time: 4:00PM
Where: Tech Institute - Room M345
Contact Person: Sandip Ghosal
Contact email: s-ghosal@northwestern.edu
Contact Phone: 847-4675990
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