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SUMMARY:Fluid Mechanics Tour of the Alps : Coherent structures in natural 
 and forced turbulent jets
DTSTART:20260507T101500
DTEND:20260507T111500
DTSTAMP:20260526T042736Z
UID:af0fdfc2769afee4e374293f47b72fe3a5ec5815af4741699a8f560f
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Tim Colonius\nBio :\nTim Colonius is the Frank and Ora L
 ee Marble Professor of Mechanical Engineering at the California Institute 
 of Technology.  He received his B.S. from the University of Michigan in 1
 987 and M.S and Ph.D. in Mechanical Engineering from Stanford University i
 n 1988 and 1994\, respectively.   He and his research team use numerical 
 simulations to study a range of problems in fluid dynamics\, including aer
 oacoustics\, flow control\, instabilities\, shock waves\, and bubble dynam
 ics.   Prof. Colonius also investigates medical applications of ultrasoun
 d and is a member of the Medical Engineering faculty at Caltech.  He is a
  Fellow of the American Physical Society and the Acoustical Society of Ame
 rica.  He is the recipient of the AIAA Aeroacoustics Award\, the APS Stan
 ley Corrsin Award\, and the ASME Freeman Scholar Award.\n\nAbstract :\nAcr
 oss a wide range of engineering and environmental flows\, predictive model
 ing hinges on isolating the components of turbulent motion that evolve coh
 erently in space and time. Turbulence is inherently stochastic\, but not a
 ll fluctuations contribute equally: a relatively small subset exhibits cor
 related dynamics and accounts for a disproportionate share of transport\, 
 mixing\, and noise. This talk presents a framework for identifying\, inter
 preting\, and modeling those components in a way that connects statistical
  description to underlying dynamics. Spectral proper orthogonal decomposit
 ion (SPOD) provides a statistically optimal description of structures that
  evolve coherently in space and time\, isolating the dynamically relevant 
 motions embedded within turbulence. When viewed alongside resolvent analys
 is of the linearized Navier–Stokes equations\, a more complete picture e
 merges: SPOD reveals what the flow does\, while the resolvent framework ex
 plains why—linking observed structures to amplification mechanisms and t
 o the nonlinear interactions that sustain them. Together\, these tools exp
 ose how Kelvin–Helmholtz instability\, Orr amplification\, and lift-up m
 echanisms compete and interact across frequency and azimuthal wavenumber\,
  illustrated here in the canonical setting of high-speed jets. Building on
  this interpretation\, we show how resolvent models\, augmented with eddy-
 viscosity closures\, can predict dominant flow structures directly from th
 e mean flow\, offering a practical route toward reduced-order models with 
 predictive capability. Finally\, we extend the framework to time-periodic 
 and forced flows using cyclo-stationary statistics\, enabling analysis of 
 more realistic\, externally driven configurations.\n 
LOCATION:MED 0 1418 https://plan.epfl.ch/?room==MED%200%201418
STATUS:CONFIRMED
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