IUTAM Transition 2019 logo

Schedule

7:45am - 8:45am
Registration, Arrival & Coffee
Main Foyer
8:45am - 9:00am
Opening
Room 200

Chair: Peter Schmid (Imperial College London)
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Abstract

In this lecture, an overview of the laminar-turbulent transition research conducted by the speaker and his colleagues at NASA during the past few decades will be presented. This includes development of computational methods for compressible stability analysis, linear and nonlinear parabolized stability equations, supersonic and hypersonic boundary layer transition prediction including the effects of nose bluntness and gas chemistry, development of quite supersonic and hypersonic tunnels, resolution of cone-to-flat plate transition controversy, instability and transition of rotating disk flow, secondary instability of crossflow disturbances and instability of the attachment-line boundary layer. Various laminar flow control research efforts will be briefly discussed. The talk will close by addressing current challenges in laminar-turbulent transition prediction.
Chair: Hermann Fasel (University of Arizona)
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10:00am - 10:20am
Subcritical Laminar-Turbulent Transition on Blunt Cones at Hypersonic Speeds
Pedro Paredes, Meelan M. Choudhari, Fei Li
10:20am - 10:40am
Numerical Investigation of the Nonlinear Transition Stages in a High-Enthalpy Hypersonic Boundary Layer on a Right Cone
Michelle Bailey, Christoph Hader, Hermann Fasel
10:40am - 11:00am
Controlled Stationary/Traveling Cross-flow Mode Interaction in Mach 6 Boundary Layer
Alexander Arndt, Thomas Corke, Eric Matlis, Michael Semper
11:00am - 11:20am
Sensitivity of Boundary-Layer Stability and Transition to Thermochemical Modelling
Heather L. Kline, Chau-Lyan Chang, Fei Li
11:20am - 11:40am
Nonlinear PSE Transition Predictions in Hypersonic Boundary Layers with Finite Rate Chemical Reactions
Ludovico Zanus, Fernando Miró Miró, Fabio Pinna
11:40am - 12:00pm
Sensitivity of Hypersonic Shear Flows to Finite-Rate Chemistry Effects and Surface Roughness
Athanasios Margaritis, Taraneh Sayadi, Olaf Marxen, Peter Schmid
12:00pm - 1:15pm
Lunch & Posters (E,F & G)
Main Foyer

Chair: Xuesong Wu (Imperial College London)
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Abstract

In this presentation, a brief overview is first given of our past numerical simulation research of hypersonic boundary-layer receptivity and instability mechanism, conducted in collaboration with my past and current graduate students. Subsequently, our recent results will be presented on the computational and theoretical studies of the supersonic mode in hypersonic boundary layers. Since a few years ago, there has been renewed interest in supersonic modes in hypersonic boundary layers, which have previously been thought to be insignificant due to their smaller amplitudes than Mack's traditional second mode. Supersonic modes are associated with an unstable second Mack mode synchronizing with the slow acoustic spectrum, causing sound to radiate outwards from the boundary layer. Because supersonic modes have yet to be observed experimentally, the majority of previous investigations mainly relied on the Linear Stability Theory (LST) to study supersonic modes on a flat plate. We will present our recent results from a combined LST and Direct Numerical Simulation (DNS) approach to investigate the mechanism of supersonic modes under various flow conditions for hypersonic flow over blunt cones with or without the thermochemical nonequilibrium effects.
Chair: Jacob Cohen (Technion)
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2:00pm - 2:20pm
Destabilisation of Stationary and Travelling Crossflow Disturbances Due to Forward and Backward Facing Steps over a Swept Wing
Emma Cooke, Shahid Mughal, Spencer Sherwin, Richard Ashworth, Stephen Rolston
2:20pm - 2:40pm
BiGlobal Stability Analysis of a Swept-Wing Boundary Layer with Forward and Backward Facing Steps
Thibaut Appel, Emma Cooke, Richard Ashworth, Shahid Mughal
2:40pm - 3:00pm
Effects of 3D Roughness Patch on Transition in High-Speed Boundary Layers
Meelan M. Choudhari, Fei Li, Pedro Paredes
3:00pm - 3:20pm
Receptivity from Surface Imperfections.
Michael Gaster
3:20pm - 3:40pm
Influence of superhydrophobic surfaces on the laminar-to-turbulent transition in a channel flow
Francesco Picella, Jean-Christophe Robinet, Stefania Cherubini
3:40pm - 4:00pm
Transition in a Swept-boundary Layer Subject to Surface Roughness and Free-stream Turbulence
Luca De Vincentiis, Dan Henningson, Ardeshir Hanifi
4:00pm - 4:30pm
Break & Posters (E,F & G)
Main Foyer
Chair: Vassilis Theofilis (University of Liverpool)
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4:30pm - 4:50pm
Optimal Force and State Reconstruction
Eduardo Martini, Andre Cavalieri, Peter Jordan, Lutz Lesshafft, Aaron Towne
4:50pm - 5:10pm
Global Stability Analysis of the JAXA H-II Transfer Vehicle Re-Entry Capsule
Andrea Sansica, Atsushi Hashimoto, Yuya Ohmichi
5:10pm - 5:30pm
Overview of the PDE-Based Amplification Factor Transport Model as an Engineering Tool for Transition Prediction in Complex Aerodynamic Flows
James Coder
5:30pm - 5:50pm
Reduced order model of shock-boundary layers interactions
Guillaume Chauvat, Peter J. Schmid, Daniel J. Bodony, Vassilis Theofilis, Ardeshir Hanifi
5:50pm - 6:10pm
Global Stability of Fluid-Structure Interaction Problems
Prabal Singh Negi, Ardeshir Hanifi, Dan Henningson
6:10pm - 6:30pm
Numerical Investigations of Laminar to Turbulent Transition on an Oscillating Airfoil Boundary Layer
Duncan M. Ohno, Jonas P. Romblad, Marwan Khaled, Ulrich Rist
6:30pm - 6:50pm
Transient growth and self-sustained turbulence in Couette-Poiseuille flow
Benoit Semin, Lukasz Klotz, Alexandr Pavlenko, Tao Liu, José Eduardo Wesfreid
7:00pm - 8:30pm
Welcome Reception
Main Foyer
8:30am - 9:00am
Arrival & Coffee
Main Foyer

Chair: Marcello A. F. Medeiros (University of Sao Paulo)
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Abstract

We review results of experimental investigations into transition in pipe and Couette flows. The outcomes of this work are used to interpret our ex- perimental findings on the decay of turbulence in Couette-Poiseuille flow. We have used PIV techniques to help identify the salient structures of the flow field and thereby elucidate the energy distribution. In particular we have identified that the energy distribution decays anisotropically providing new insights into transition processes in shear flows.
Chair: Stefan Hein (Deutsches Zentrum fuer Luft- und Raumfahrt e.V. (DLR))
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10:00am - 10:20am
Distributed Excitation of Crossflow Waves Due To Scattering of Freestream Vortices on Surface Waviness
Yury S. Kachanov, Vladimir I. Borodulin, Andrey V. Ivanov
10:20am - 10:40am
Boundary-Layer Receptivity to Entropy Waves in Subsonic and Transonic Flows.
Anatoly I. Ruban, Marina A. Kravtsova, Sharad Keshari
10:40am - 11:00am
Linear and nonlinear stability of forced planar liquid jets
Simon Schmidt, Kilian Oberleithner
11:00am - 11:20am
Acoustic receptivity of Tollmien-Schlichting waves to localised surface roughness
Marco Placidi, Michael Gaster, Chris Atkin
11:20am - 11:40am
On the Effects of the Acoustic Wave Angle of Incidence in Subsonic Acoustic Receptivity
Henrique Raposo, Shahid Mughal, Richard Ashworth
11:40am - 12:00pm
Receptivity of unsteady compressible Gortler vortices to free-stream vortical disturbances
Samuele Viaro, Pierre Ricco
12:00pm - 1:15pm
Lunch & Posters (C & D)
Main Foyer

Chair: Yury Kachanov (Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, 630090, Russia)
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Abstract

Transition location in the boundary layer on the swept wing is rather sensitive to surface roughness and level of free-stream turbulence [1,2]. Conventional e^N method based on computation of linear amplification coefficients of instability modes can not describe dependence of transition Reynolds number from these factors. Alternative amplitude method of cross-flow dominated transition prediction based on computation of amplitudes of steady and traveling cross-flow instability modes is developed here. Initial amplitudes of disturbances in the boundary layer are found by means of decomposition of free-stream turbulence and surface roughness into a set of periodical waves and consideration of generation of Eigen modes in the boundary layer by these elementary waves via non-localized receptivity mechanism [3]. Subsequent evolution of steady and non-steady modes with continuous spectra and random phases is computed by simplified non-linear PSE-method. Transition location is determined as a place where the sum of amplitudes of steady and non-steady modes reaches a threshold value 0.34. This transition criterion was recently introduced from analysis of experimental data for wide range of surface roughness and turbulence level in [4]. The amplitude method developed reproduces satisfactorily the dependence of transition location on the Reynolds number, the surface roughness, and free-stream turbulence level observed in experiments [1, 2]. Moreover, it gives the evolution of almost all measurable characteristics of the base flow and perturbations in the transition region. In particular, it describes saturation of the growth of steady and traveling modes and the deformation of the velocity profiles in the boundary layer initiated by these modes. This amplitude method of transition prediction is rather simple and does not require large amount of computations. It can be used in future for operative prediction of transition location instead of e^N method.

References
[1] Radeztsky R.H., Reibert M.S., Saric W.S. Effect of micron-sized roughness on transition in swept-wing flows. AIAA J. 37(11):1370–1377. 1999
[2] Deyhle H., Bippes H. Disturbance growth in an unstable three-dimensional boundary layer and its dependence on initial conditions// J. Fluid Mech. 316: 73-113., 1991
[3] Crouch J.D. Non-localized receptivity of boundary layers. J. Fluid Mech. 224:567–581, 1992.
[4] Crouch J.D., Ng L.L., Kachanov Y.S., Borodulin V.I., Ivanov A.V. Influence of surface roughness and free-stream turbulence on crossflow-instability transition. Procedia IUTAM, 2015. V. 14. IUTAM_ABCM Symposium on Laminar Turbulent Transition / Eds.: M.A.F. Medeiros & J.R. Meneghinipp, P. 295–302.
Chair: George Papadakis (Imperial College)
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2:00pm - 2:20pm
Experimental Investigation of Spanwise Periodic Surface Heating for Control of Crossflow-Dominated Laminar-Turbulent Transition
Hans Peter Barth, Stefan Hein
2:20pm - 2:40pm
Real-time feedback control of TS waves
Jonathan Morrison, Hari Vemuri, Richard Bosworth, Eric Kerrigan
2:40pm - 3:00pm
Nonlinear Optimal Control in Shear Flows using Deep Reinforcement Learning
Onofrio Semeraro, Michele Alessandro Bucci, Alexandre Allauzen, Guillaume Wisniewski, Laurent Cordier, Lionel Mathelin
3:00pm - 3:20pm
Nonlinear Optimal Control of Transition due to a Pair of Vortical Perturbations using a Receding Horizon Approach
George Papadakis, Dandan Xiao
3:20pm - 3:40pm
Active Attenuation of a Trailing Vortex Inpsired by Stability Analysis
Louis Cattafesta, Ross Richardson, Adam Edstrand, Yiyang Sun, Kunihiko Taira, Peter Schmid
3:40pm - 4:00pm
Delay of bypass transition via data-driven reduced order modeling and control theory
Pierluigi Morra, Kenzo Sasaki, Ardeshir Hanifi, André V. G. Cavalieri, Dan S. Henningson
4:00pm - 4:30pm
Break & Posters (C & D)
Main Foyer
Chair: Thomas Corke (University of Notre Dame, Colorado Springs)
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4:30pm - 4:50pm
Experimental Investigation of Crossflow Instabilities
Tariq Saeed, Jonathan Morrison
4:50pm - 5:10pm
Investigation on the freestream turbulence amplification approaching the attachment-line of swept circular cylinders using multi-component LDA
Isabella Fumarola
5:10pm - 5:30pm
Instabilities and transition on a rotating cone – old problems and new challenges
Kentaro Kato, Antonio Segalini, P. Henrik Alfredsson, R. J. Lingwood
5:30pm - 5:50pm
Interaction of free-stream turbulence and discrete roughness on boundary-layer transition
Shumpei Hara, Santhosh Babu Mamidala, Jens Henrik Mikael Fransson
5:50pm - 6:10pm
Reynolds number dependence on very-large-scale features in transitional and turbulent channel flows
Masaharu Matsubara, Yu Imanishi, Yuya Tanada, Sattaya Yimprasert, Yutaro Endo, Tatsuya Tsumura
6:10pm - 6:30pm
On the importance of free-stream turbulence length scale in boundary-layer transition
Jens Henrik Mikael Fransson
6:30pm - 6:50pm
Experimental characterization of the effects of two-dimensional surface defects on the laminar-turbulent transition of a sucked boundary layer
Jeanne Cam-Tu Methel, Maxime Forte, Olivier Vermeersch, Grégoire Casalis
8:30am - 9:00am
Arrival & Coffee
Main Foyer

Chair: Yongyun Hwang (Department of Aeronautics, Imperial College London)
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Abstract

Transitional and turbulent flows are characterized by coherent structures, fluid motions highly correlated over both space and time in the form of small- and large- scale streaks and hairpin vortices, which carry a much larger momentum than the chaotic motion at small scales. It is now known that streaks arise due to a linear mechanism of transient energy growth, which is one of the main mechanisms allowing the self-sustainment of exact invariant solutions of the Navier-Stokes equations (equilibria, travelling waves, periodic orbits), which populate the state space capturing most of the organized flow structures recurrently observed. However, the commonly observed hairpin vortices still not have a clear place in this dynamical system view of turbulence, their origin being mostly unclear. Using a nonlinear optimization approach, in this talk we will identify and characterise highly energetic transient events such as the growth of hairpin vortices and the recurrence of bursts in transitional and turbulent flows as optimal flow structures. We will show that these optimal coherent structures reproduce well the spatial spectra and the probability density function of the velocity typically measured in turbulent flows. Finally, we use the nonlinear optimization in the framework of the dynamical system view of turbulence, showing how hairpin vortices emerge along a strongly amplified path in the stable manifold of an exact invariant traveling wave solutions. Stable manifolds, although exponentially contracting for infinite time, allow excursions on a finite time horizon and may thus provide the necessary connectivity between invariant solutions supporting turbulence. These results imply that hairpin vortices, even if inherently transient coherent structures, are robust features of transitional and turbulent shear flows, resulting from strong nonlinear transient growth that repeats in time as a by-product of the self-sustained wall cycle.
Chair: Olaf Marxen (University of Surrey)
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10:00am - 10:20am
Numerical / experimental investigations of the effect of transpiration cooling on second mode instabilities in hypersonic, conical flows
Viola Wartemann, Giannino Ponchio Camillo, Alexander Wagner
10:20am - 10:40am
Roughness-Induced Laminar-Turbulent Transition in the Boundary Layer of a Capsule-Like Geometry at Mach 20 Including Non-Equilibrium
Christian Stemmer, Antonio Di Giovanni
10:40am - 11:00am
Influence of High-Temperature Effects on the Stability of the Wake Behind an Isolated Roughness Element in Hypersonic Flow
Iván Padilla Montero, Fernando Miró Miró, Fabio Pinna
11:00am - 11:20am
Instability analysis of under-expanded supersonic impinging jets
Shahram Karami, Vassilis Theofilis, Julio Soria
11:20am - 11:40am
Effect of the streaky structures on the instabilities in supersonic boundary layers
Jianxin Liu, Xuesong Wu
11:40am - 12:00pm
Direct Numerical Simulations (DNS) of “natural” transition in high-speed boundary layers using a broadband random forcing approach
Christoph Hader, Hermann Fasel
12:00pm - 12:20pm
The Role of Receptivity in Prediction of High-Speed Laminar-Turbulent Transition
Ivan Egorov, Alexander Fedorov, Andrey Novikov
12:20pm - 2:00pm
Lunch & Posters
Main Foyer
2:00pm - 6:30pm
Free time for activities
8:30am - 9:00am
Arrival & Coffee
Main Foyer

Chair: Spencer J Sherwin (Imperial College London)
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Abstract

Transition to turbulence in high-speed boundary layers is very sensitive to the environmental conditions. Even seemingly negligible changes in the spectral content of free-stream disturbances can appreciably shift transition location, alter the heat-transfer rate on the wall and significantly affect drag. This sensitivity, combined with the wealth of possible mechanisms for transition to turbulence, present a challenge: How can any simulation provide meaningful predictions when flight conditions are often uncertain? In order to address this challenge, we set out to determine the earliest possible transition location for a given flow, independent of the spectral makeup of the environment. We call this condition the “nonlinearly most dangerous disturbance”. The problem is formulated as a constrained optimization, where the objective is to identify the inflow disturbance that leads to the lowest transition Reynolds number in a Mach 4.5 zero-pressure-gradient boundary layer. The constraints are the initial disturbance total energy and that the flow satisfies the full nonlinear Navier-Stokes equations. The results are surprising and cannot be ascribed to classical transition scenarios. Through a series of nonlinear energy exchanges, our inflow disturbance modifies the base state and spurs new instabilities that cause transition to turbulence upstream of any other inflow condition. We have also devised new approaches to enhance the fidelity of our simulations, so they are more representative of experimental and flight conditions. Our methodologies are robust, and applicable with any computational approach.
Chair: Georgios Rigas (California Institute of Technology)
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10:00am - 10:20am
What can we learn from the Edge about bypass transition?
Miguel Beneitez, Yohann Duguet, Philipp Schlatter, Dan S. Henningson
10:20am - 10:40am
The minimal seed for wall-bounded transition in the frequency domain
Georgios Rigas, Denis Sipp, Tim Colonius
10:40am - 11:00am
Nonlinear optimal disturbances in compressible shear flows
M. J. Philipp Hack, Zhu Huang, Tim Flint
11:00am - 11:20am
Amplitude-Dependent Three-Dimensional Neutral Modes in Plane Poiseuille-Couette Flow at Large Reynolds Number
Rishi Kumar, Andrew Walton
11:20am - 11:40am
Distributed VWI arrays and the emergence of self-similarity in turbulent shear flows.
philip hall
11:40am - 12:00pm
Transition in Rotating Plane Couette Flow, Revisited
Masato Nagata, Baofang Song, Darren P. Wall
12:00pm - 1:15pm
Lunch & Posters (A & B)
Main Foyer

Chair: Ardeshir Hanifi (KTH Royal Institute of Technology)
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Abstract

Large-scale coherent structures have been observed in turbulent flows for some decades. Their behaviour has been modelled using linear stability analysis of the mean flow; for instance, models for jets predict the appearance of a hydrodynamic wavepacket, due to spatial amplification, saturation and decay of Kelvin-Helmholtz modes. However, early comparisons between stability results and experiments were often of qualitative nature, due to the intrinsic difficulty of isolating wavepackets amidst a turbulent flow. This talk reviews linear analysis for turbulent flows, focusing on more recent developments, where coherent turbulent structures are modelled as the most amplified flow response to non-linear excitation via resolvent analysis. Spectral proper orthogonal decomposition (SPOD) appears as the natural approach to obtain coherent structures from spatio-temporal data from experiment or simulation; such structures can in turn be quantitatively compared to the most amplified responses from resolvent analysis. The approach is exemplified by comparisons between theoretical and experimental wavepackets in turbulent subsonic jets. Moreover, the same linear methods are used for the analysis of recently discovered phenomena within turbulent jets: acoustic modes trapped in the potential core, and large-scale streaks.
Chair: Leonardo Alves (UFF)
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2:00pm - 2:20pm
Use of instabilities for optimal laminar separation delay
Michael Karp, M. J. Philipp Hack
2:20pm - 2:40pm
Transient growth analysis of the flow around an elastically mounted circular cylinder
Daiane I. Dolci, Bruno S. Carmo
2:40pm - 3:00pm
Instabilities in laminar shock boundary layer interactions
Nathaniel Hildebrand, Anubhav Dwivedi, Sidharth GS, Joseph Nichols, Mihailo Jovanovic, Graham Candler
3:00pm - 3:20pm
On a new non-modal instability in a two-dimensional disk-type flow
Tim Gebler, Judith Kahle, Dominik Plümacher, Martin Oberlack
3:20pm - 3:40pm
Instability of tilted shear flow in a strongly stratified and viscous medium
Yongyun Hwang, Lloyd Fung
3:40pm - 4:00pm
Taking advantage of randomness to empower resolvent analysis
Jean Helder Marques Ribeiro, Chi-An Yeh, Kunihiko Taira
4:00pm - 4:30pm
Break & Posters (A & B)
Chair: Pierre Ricco (University of Sheffield)
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4:30pm - 4:50pm
Time-evolving network analysis of two-dimensional turbulence
Chi-An Yeh, Muralikrishnan Gopalakrishnan Meena, Kunihiko Taira
4:50pm - 5:10pm
Study of Transition to Turbulence using Discrete Directed Percolation Model
Kouta Watanabe, Hideki Shiiba, Yoshio Ishii
5:10pm - 5:30pm
Spatially localized states and their dynamics in transitional plane Couette flow
Anton Pershin, Cedric Beaume, Steven Tobias
5:30pm - 5:50pm
On Subharmonic Resonance and Other Nonlinear Mechanisms in Wavepackets in Boundary Layers
Marcello A. F. Medeiros, Fernando H. T. Himeno, Marlon S. Mathias, Andrés G. Martinez
5:50pm - 6:10pm
Nonlinear evolution of multiple helical modes on subsonic circular jets with a large radius: a weakly nonlinear critical-layer theory
Zhongyu Zhang, Xuesong Wu
6:10pm - 6:30pm
On the role of actuation for the control of streaky structures in boundary layers
André V. G. Cavalieri, Kenzo Sasaki, Pierluigi Morra, Ardeshir Hanifi, Dan S. Henningson
7:00pm - 10:00pm
Symposium Dinner
Senior Common Room
8:30am - 9:00am
Arrival & Coffee
Main Foyer
Chair: Pedro Paredes (National Institute of Aerospace)
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9:00am - 9:24am
Receptivity of a hypersonic blunt cone boundary layer to slow acoustic wave: role of entropy-layer disturbance
Caihong Su, BingBing Wan
9:24am - 9:48am
Receptivity of inviscid mode in supersonic boundary layers due to interaction of freestream acoustic waves and wall roughness
Ming Dong
9:48am - 10:12am
Global stability analysis and DNS of a swept airfoil section in subsonic flow
Neil D. Sandham, Nicola De Tullio
10:12am - 10:36am
Experimental Study of Distributed Receptivity Coefficients at Excitation of Crossflow Waves by Freestream Vortices
Vladimir I. Borodulin, Andrey V. Ivanov, Yury S. Kachanov
10:36am - 11:00am
Effect of discrete widely spaced suction on a transitioning flow at high suction rates
Barry Crowley, Chris Atkin
11:00am - 11:30am
Break & Posters
Main Foyer
Chair: William Saric (Texax A&M University)
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11:30am - 12:15pm
Progress in Stability and Transition Research
Helen Reed
12:15pm - 1:00pm
Predicting laminar-turbulent transition influenced by surface-induced flow distortions
Jeffrey Crouch