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SUMMARY:Insights from minimal simulations of rough-wall turbulence - Dr. D
 aniel Chung. University of Melbourne\, Australia
DTSTART:20170421T120000Z
DTEND:20170421T130000Z
UID:TALK72171@talks.cam.ac.uk
CONTACT:Garazi Gomez-de-Segura
DESCRIPTION:Rough-wall turbulence is the rule rather than the exception in
  engineering and nature. Progress in understanding rough-wall turbulence h
 as been difficult owing to the infinite number of roughness geometries\, c
 ompounded by the prohibitive experimental or computational costs associate
 d with dynamically characterising each roughness geometry. Consequently\, 
 roughness research has been a large-scale\, decades-long effort in catalog
 ing and empirical modelling. Even so\, the accuracy of predictions| is que
 stioned whenever unfamiliar roughness geometries are encountered or exacti
 ng designs are required. In a paradigm shift\, I will discuss an alternati
 ve approach to understanding rough-wall turbulence in general. The method\
 , namely minimal simulations\, is originally developed in the context of s
 mooth walls by Jiménez and Moin (1991) for the buffer layer and by Flores
  and Jiménez (2010) for the log layer. Recently\, the method is extended 
 by Chung et al. (2015) to rough-wall turbulence. The method provides a fra
 mework in which to directly simulate only the scales associated with rough
 ness modification and is therefore fast\, cheap and accurate. Because the 
 method is specific to the roughness in question and is relatively cheap to
  evaluate\, it lessens the need for empiricism. After presenting an overvi
 ew of the method\, I will discuss recent insights from the method applied 
 to previously difficult-to-reach parameter spaces\, including dense sinuso
 ids and deep bars.
LOCATION:JDB Seminar Room\, CUED
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