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CATEGORIES:Isaac Newton Institute Seminar Series
SUMMARY:Statistical analysis of non-linearities in turbule
nce - Andre Cavalieri (Instituto Tecnológico de Ae
ronáutica)
DTSTART;TZID=Europe/London:20220330T113000
DTEND;TZID=Europe/London:20220330T120000
UID:TALK171185AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/171185
DESCRIPTION:Recent years have seen significant progress in the
analysis of coherent structures in turbulent flow
s via an input-output framework\, where non-linear
terms\, considered as "forcing"\, drive a flow re
sponse through the resolvent operator\, obtained b
y a linearisation of the Navier-Stokes system arou
nd the mean flow. This leads to models that often
provide a good approximation of dominant coherent
turbulent structures as the flow responses with ma
ximal amplification by the resolvent. However\, ac
curate quantitative agreement depends on the speci
fic details of the forcing. In this presentation w
e will explore non-linear terms from simulations o
f turbulent channel flow and their connection to f
low responses. The statistics of such non-linear t
erms are seen to have low rank\, implying that coh
erent structures are driven by non-linear interact
ions that are also coherent\; this is in contrast
with the usual white-noise forcing assumption in l
inearised models. Non-linear terms are also seen t
o be approximately self-similar across a broad ran
ge of scales. Such properties provide directions t
o improve existing models of turbulent structures
based on the linearised operator\, and also to bui
ld accurate linear estimators for turbulent flows.
LOCATION:Seminar Room 1\, Newton Institute
CONTACT:
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