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Slow growth approximation for near wall patch representation of wall-bounded turbulence

Event Type: 
Date and Time: 
Friday, March 4, 2022 - 16:15
Location: 
Building 300, Room 300
Event Sponsor: 
Parviz Moin, Director of Center for Turbulence Research
Speaker(s): 
Dr. Sean Carney

Recent experimental and computational studies have demonstrated that wall-bounded turbulent shear flows exhibit universal  small-scale  dynamics  that  are  modulated  by  large-scale  flow  structures.  This  characterization  can  be complicated, however, by stronger pressure gradients; they can cause significant variation of the mean flow in the streamwise direction. For such situations, we perform asymptotic analysis of the Navier-Stokes equations valid whenever  the  viscous  length  scale  is  small  relative  to  the  length  scale  over  which  the  mean  flow  varies.  The asymptotics inform a model for the effect of mean flowgrowth on near-wall turbulence in a small domain localized to  the  boundary  whose  size  scales  in  viscous  units.  To  ensure  the  correct  momentum  environment,  a  dynamic procedure is introduced that accounts for the additional sources of mean momentum flux through the upper domain boundary arising from the asymptotic terms. Comparisons of the model's low-order, single-point statistics with those  from  direct  numerical  simulation  and  wall-resolved  large  eddy  simulation  of  adverse  pressure  gradientboundary layers indicate the asymptotic model successfully accounts for the effect of boundary layer growth on the small-scale near-wall turbulence.

Bio: 
Dr. Sean Carney is a Hedrick Assistant Adjunct Professor at the University of California, Los Angeles. His postdoctoral research focuses on phase field modeling for complex fluid mixtures at the microscale. He received his PhD in May 2020from The University of Texas at Austin under the supervision joint of Bjorn Engquist and Robert Moser. His PhD thesis focused on multiscale simulation techniques for rough-wall laminar flow and high Reynolds number turbulent flow. He has also spent time at the Center for Computational Science and Engineering of the Lawrence Berkeley National Laboratory, working on stochastic modeling of electro-kinetic flows, also a topic of current interest.