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SUMMARY:Intermittency in imperfect multiplicative cascades - Jimenez\, J (
 Aeronautics\, UP Madrid)
DTSTART:20080930T090000Z
DTEND:20080930T093000Z
UID:TALK13841@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:The standard multifractal cascade model assumes both a Markovi
 an self-similar multiplicative cascade\, and locality\, in the sense that 
 point properties depend only on their immediate neighbourhoods. Relaxing t
 he second condition leads to more general cascades in which a point proper
 ty v_{n+1} depends both on the local previous cascade step v_n\, and on th
 e global variance v'_n. The first contribution models a local breakdown pr
 ocess\, while the second represents the effect of the background perturbat
 ions. There are two stochastic multipliers\, one for each term\, and they 
 are characterised empirically for experimental high-Reynolds number experi
 mental turbulence. General conditions are derived for such an imperfect mu
 ltiplicative cascade to be intermittent\, in the sense of creating unbound
 ed high-order flatness factors after many steps. The experimental values a
 re such as to be most likely intermittent\, but they may not reach true mu
 ltifractal distributions\, and power laws for the structure functions\, un
 til extremely large Reynolds numbers.
LOCATION:Seminar Room 1\, Newton Institute
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