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SUMMARY:Direct numerical simulations of motile bacteria in the turbulent o
 cean - Dr Romain Watteaux\, DAMTP
DTSTART:20131129T160000Z
DTEND:20131129T170000Z
UID:TALK48054@talks.cam.ac.uk
CONTACT:Dr C. P.  Caulfield
DESCRIPTION:Nearly one-half of the global primary production of organic ca
 rbon compounds occurs in the oceans. Between 30 and 50\\% of the newly gen
 erated carbon is released into the seawater as dissolved organic matter (D
 OM)\, and is almost exclusively accessible to bacteria. When a patch of nu
 trients is released in a turbulent flow\, it is fragmented into a series o
 f filaments whose width is affected by the rates of stirring and diffusion
 . Chemotactic bacteria are able to move up the resulting nutrient gradient
 s b introducing a bias in their random mobility in response to chemical cu
 es. Here\, motile bacteria are simulated using a Keller-Segel model\, embe
 dded in direct numerical simulations of a turbulent flow. A spectral analy
 sis of the governing equations shows how both the nutrient and bacteria fi
 elds are affected by the flow and chemotaxis. Motility confers an advantag
 e\, but distribution functions show that bacterial uptake is strongly disc
 riminatory among the population. Secondly\, we present a sensitivity study
  of the bacterial uptake\, showing that for most of the parameter space\, 
 motile bacteria benefit from the turbulent flow. We propose a scaling law 
 for the uptake rate\, accounting for a wide range of physical and biologic
 al parameters.
LOCATION:MR2\, Centre for Mathematical Sciences\, Wilberforce Road\, Cambr
 idge
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