Seminars

Cellular NeuroMechanics – Concussions, Traumatic Brain Injury and the mysterious Havana Syndrome

Christian Franck

Grainger Institute for Engineering Professor
Department of Mechanical Engineering
University of Wisconsin-Madison
Madison, Wisconsin

Current prediction, prevention and diagnosis strategies for mild traumatic brain injuries, including concussions, are still largely in their infancy due to a lack of detailed understanding and resolution of how physical forces give rise to tissue injury at a cellular level. In this talk I will present some recent work on our current understanding of the origin of concussions and traumatic brain injuries and how cells in the brain interpret and react to the physical forces of trauma. Specifically, I will show that the path to a better understanding of traumatic injuries involves addressing a variety of finite deformation, rate-dependent soft matter and cell mechanics problems along the way. Finally, I will provide an update on how our current understanding of the cellular neuromechanics cannot only help shed light on improving our prediction of TBI but also enable us to dissect the physical origin of emerging injuries such as the Havana Syndrome.

Christian Franck is a mechanical engineer specializing in cellular biomechanics and new experimental mechanics techniques at the micro and nanoscale. He received his B.S. in aerospace engineering from the University of Virginia in 2003, and his M.S. and Ph.D. from the California Institute of Technology in 2004 and 2008. Dr. Franck held a post-doctoral position at Harvard investigating brain and neural trauma. He was an assistant and associate professor in mechanics at Brown University from 2009 - 2018, and is now the Grainger Institute for Engineering Professor in Mechanical Engineering at the University of Wisconsin-Madison.

His lab at the University of Wisconsin-Madison has developed unique three-dimensional full-field imaging capabilities based on multiphoton microscopy and digital volume correlation. Current application areas of these three-dimensional microscopy techniques include understanding the 3D deformation behavior of neurons in the brain during traumatic brain injuries, and the role of non-linear material deformations in soft matter.

He is the acting director of the Center for Traumatic Brain Injury at the University of Wisconsin-Madison and the ONR-funded Physics-based Neutralization of Threats to Human Tissues and Organs (PANTHER) program, which consists of over 24 PIs nationwide. Key objectives of the Panther program are in better detection, prediction, and prevention of traumatic brain injuries by providing accelerated translation from basic science discovery to civilian and warfighter protection solutions.

Wednesday, January 12, 2022

3:30 PM

Seminar will be by Zoom only.

The Zoom webinar is at
https://usc.zoom.us/j/93987337017?pwd=MWd2dXBSL1FaR1RPaHNscjJ1NW80UT09.

Elucidating the Thermodynamic Origins of Reaction Heterogeneity in Lithium-Ion Batteries

Ming Tang

Associate Professor
Department of Materials Science and NanoEngineering
Rice University
Houston, TX

During battery cycling, pronounced reaction non-uniformity frequently develops at multiple length scales within electrodes, which adversely impacts battery performance and life by inducing capacity under-utilization, stress concentration and over-(dis)charging. While heterogeneous reactions are typically attributed to mass transport limitations, thermodynamic factors also play an important role and need to be clarified for developing effective mitigation strategies. At the particle level, we reveal how stress could destabilize the lithium (de)lithiation front in single crystalline and polycrystalline intercalation compounds. Stress also provides a fundamental thermodynamic driving force for dendrite growth on lithium metal anodes, which is shown to be effectively suppressed by stress relief. At the cell level, we discover that the reaction distribution within the porous electrode is strongly influenced by how the equilibrium potential of the active material varies with the state of charge. Two types of reaction behavior are identified for common electrode materials, which have significant implications for their applications in thick electrodes. Based on this finding, an analytical model is formulated to provide highly efficient battery performance predictions and optimization in place of traditional battery cell simulations.

Ming Tang is an Associate Professor in the Department of Materials Science and NanoEngineering at Rice University. After receiving a Ph.D. degree in Materials Science and Engineering from MIT, He worked at Lawrence Livermore National Laboratory as a Lawrence Postdoctoral Fellow and then a staff scientist. In 2013 he joined Shell Oil as a materials and corrosion engineer, and became an assistant professor at Rice University in 2015. His group is currently interested in applying combined modeling and experimental methods to understand mesoscale phenomena in energy storage systems and use the acquired knowledge to guide microstructure design. He is a recipient of the DOE Early Career Award.

Wednesday, January 19, 2022

3:30 PM

Seminar will be by Zoom only.

The Zoom webinar is at https://usc.zoom.us/j/93987337017?pwd=MWd2dXBSL1FaR1RPaHNscjJ1NW80UT09.

host: Renuka Balakrishna

Cool Fuel: Engineering Liquid Hydrogen for the Future of Zero-Carbon Transportation

Jacob Leachman

Associate Professor
School of Mechanical and Materials Engineering
Washington State University
Pullman, WA

The new HydrogenShot initiative launched by the US Department of Energy has the ambitious goal of reducing hydrogen fuel production costs to $1 for 1 kg in 1 decade. Behind the scenes of this goal is an incredible logistics challenge to store and distribute the massive amounts of hydrogen needed. Currently over 90% of small merchant hydrogen is distributed via cryogenic liquid tanker truck. However, modern hydrogen liquefiers have specific energy consumptions only 30% of what is theoretically achievable for ~30 tonne/day systems approaching $100M in cost. Clearly, hydrogen liquefaction cycles must fundamentally change to massively scale with clean energy resources. Once liquefied, the next challenge is minimizing parasitic heat transfer that results in boil-off losses typically between 7-40%. New paradigms for liquid hydrogen storage are needed to minimize these losses. Although many challenges remain to be solved, the purpose of this talk is to emphasize the new tools and opportunities making this cool fuel an exciting research area for several decades to come.

Jacob Leachman is an Associate Professor in the School of Mechanical and Materials Engineering at Washington State University (WSU). He initiated the Hydrogen Properties for Energy Research (HYPER) laboratory at WSU in 2010 to advance cryogenic and/or hydrogen systems. To this day the HYPER laboratory remains the only US academic laboratory focusing on cryogenic hydrogen. He earned a B.S. degree in Mechanical Engineering in 2005 and a M.S. degree in 2007 from the University of Idaho. His master’s thesis has been adopted as the foundation for hydrogen fueling standards and custody exchange, in addition to winning the Western Association of Graduate Schools Distinguished Thesis Award for 2008. He completed his Ph.D. in the Cryogenic Engineering Laboratory at the University of Wisconsin-Madison in 2010 under the advice of John Pfotenhauer and Greg Nellis. He is the lead author of the reference text “Thermodynamic Properties of Cryogenic Fluids: 2nd Edition” and “Cool Fuel: The Science and Engineering of Liquid Hydrogen” which is in development. In 2018 he received the Roger W. Boom Award from the Cryogenic Society of America.

Wednesday, January 26, 2022

3:30 PM

Zumberge Hall of Science, Room 252 (ZHS 252)

The Zoom webinar is at https://usc.zoom.us/j/93987337017?pwd=MWd2dXBSL1FaR1RPaHNscjJ1NW80UT09.

host: Bradley

Passive and Active Control of Turbulent Jets and Flames — A CFD Research

Artur Tyliszczak

Professor
Faculty of Mechanical Engineering and Computer Science
Częstochowa University of Technology
Częstochowa, Slaskie, Poland

Interest in flow control techniques is driven by a possible improvement of performance, safety and efficiency of various technical devices. Existing strategies of steering and controlling fluid flows can be divided into two approaches: passive and active. The former is based on shaping the flow domains and is usually optimized for specific flow conditions. The latter requires an external energy input (an excitation, forcing), which can be varying in response to the instantaneous flow behavior. The active methods are thus more costly but also much more flexible. Under a variety of different flow regimes, they result in a better overall response than the passive methods. In this talk, I will focus on the CFD study of passive and active control applications for jets and flames. In the latter case, proper flow control is especially important as the efficiency of combustion processes is directly related to fuel-oxidizer mixing — a process, which we would like to have under full control. I will discuss to what extent the flow field can be modified and controlled by the selection of shapes of jet nozzles or tuning of excitation parameters.

Artur Tyliszczak is a Professor in the Faculty of Mechanical Engineering and Computer Science at Częstochowa University of Technology (CUT) in Poland. He leads the CFD Research Group. He earned an M.S. degree in Mechanical Engineering in 1997 from the CUT and a PhD degree in 2002 from the CUT and von Karman Institute for Fluid Dynamics (Belgium). He worked at Cambridge University (UK) as a Marie-Curie Experienced Researcher (2010-2011) and a visiting professor (2016). His group works on the development of high-order numerical methods for CFD and their applications for open and near-wall non-reacting and reacting flows. Currently, his main research concentrates on passive and active flow control in jet type flows and flows in porous and granular layers. Artur Tyliszczak is a recipient of prestigious individual awards from the Polish scientific community, the Ministry of Science and Education, the Polish Academy of Science, the Polish Association of Theoretical and Applied Mechanics. Recently he received a Senior Award from the Fulbright Commission for his stay at USC.

Wednesday, February 2, 2022

3:30 PM

Zumberge Hall of Science, Room 252 (ZHS 252)

The Zoom webinar is at https://usc.zoom.us/j/93987337017?pwd=MWd2dXBSL1FaR1RPaHNscjJ1NW80UT09.

host: Dmaradzki

Integrated Sensing and Actuation for Robust Flight Systems

Kristi Morgansen

Professor
William E. Boeing Department of Aeronautics and Astronautics
University of Washington
Seattle, WA

A fundamental element of effective operation of autonomous systems is the need for appropriate sensing and processing of measurements to enable desired system actions. Model-based methods provide a clear framework for careful proof of system capabilities but suffer from mathematical complexity and lack of scaling as probabilistic structure is incorporated. Conversely, learning methods provide viable results in probabilistic and stochastic structures, but they are not generally amenable to rigorous proof of performance. A key point about learning systems is that the results are based on use of a set of training data, and those results effectively lie in the convex hull of the training data. This presentation will focus on use of model-based nonlinear empirical observability criteria to assess and improving and bounding performance of learning pose (position and orientation) of rigid bodies from computer vision. A particular question to be addressed is what sensing data should be captured to best improve the existing training data. The particular tools to be leveraged here focus on the use of empirical observability gramian techniques being developed for nonlinear systems where sensing and actuation are coupled in such a way that the separation principle of linear methods does not hold. These ideas will be discussed relative to both engineering applications in the form of motion planning for range and bearing only navigation in autonomous vehicles, vortex position and strength estimation from pressure measurements on airfoils, and effective strain sensor placement on insect wings for inertial measurements.

Kristi Morgansen received a BS and a MS in Mechanical Engineering from Boston University, respectively in 1993 and 1994, an S.M. in Applied Mathematics in 1996 from Harvard University and a PhD in Engineering Sciences in 1999 from Harvard University. Until joining the University of Washington, she was first a postdoctoral scholar then a senior research fellow in Control and Dynamical Systems at the California Institute of Technology. She joined the William E. Boeing Department of Aeronautics and Astronautics in the summer of 2002 as an assistant professor and is currently Professor and Chair of the department. She is also co-Director of the UW Space Policy and Research Center (UW SPARC) and is the Director of the Washington NASA Space Grant Consortium. She has received a number of awards, most recently Fellow of AIAA and member of the Washington State Academy of Sciences.

Professor Morgansen’s research interests focus on nonlinear systems where sensing and actuation are integrated, stability in switched systems with delay, and incorporation of operational constraints such as communication delays in control of multi-vehicle systems. Applications include both traditional autonomous vehicle systems such as fixed-wing aircraft and underwater gliders as well as novel systems such as bio-inspired underwater propulsion, bio-inspired agile flight, human decision making, and neural engineering. The results of this work have been demonstrated in estimation and path planning in unmanned aerial vehicles with limited sensing, vorticity sensing and sensor placement on fixed wing aircraft, landing maneuvers in fruit flies, joint optimization of control and sensing in dynamical systems, and deconfliction and obstacle avoidance in autonomous systems and in biological systems including fish, insects, birds, and bats.

Prof. Morgansen’s research focuses on guidance, navigation, control for autonomous underwater, surface, air and space systems. She is an advocate for project-based learning, inclusive engineering, multidisciplinary collaboration, and STEAM.

Wednesday, February 9, 2022

3:30 PM

The Zoom webinar is at https://usc.zoom.us/j/93987337017?pwd=MWd2dXBSL1FaR1RPaHNscjJ1NW80UT09.

Where Do Flows Separate and How Does That Affect the Optimal Control Location?

Gustaaf Jacobs

Professor
Department of Aerospace Engineering
San Diego State University
San Diego, CA

Flow separation can degrade performance in many engineering systems, through reduced lift, increased drag, and decreased efficiency. To alleviate the effects of flow separation on aerodynamic performance, active flow control has been considered since the inception of the field of aerodynamics. Open-loop flow control strategies based on various actuator technologies — such as plasma actuators, fluidic oscillators, and synthetic jets — have been shown to effectively alter separated flows, and in some cases to even yield complete reattachment. Most analyses start from the placement of an actuator at an intuitively optimal location near the separation point and/or near the Kutta condition. Optimal placement, however, requires a detailed understanding of non-linear flow separation and wake feedback that is often counterintuitive. In this talk, I will discuss recent developments in Lagrangian analysis of flow separation. This kinematic analysis promises the objective identification of separation lines as zero-mass flux "material" lines whose footprint is analytically defined from first-principle. The separation profiles start with a subtle upwelling of Lagrangian fluid tracers upstream of the separation point. Using a data-driven technique (using DNS data) I will show that these upwelling locations may well point to optimal actuator locations that require minimal control effort.

Gustaaf Jacobs received a M.Sc. in Aerospace Engineering from the Delft University of Technology in 1998, where after graduation, he was appointed to a Research Associate. He received a Ph.D. in Mechanical Engineering from the University of Illinois at Chicago. Following graduation in 2003, he was appointed Visiting Assistant Professor in the Division of Applied Mathematics at Brown University. He later combined this position with a Postdoctoral Fellowship at the Department of Mechanical Engineering at the Massachusetts Institute of Technology. As of 2006 he was appointed Assistant Professor of Aerospace Engineering at San Diego State University and was promoted to Associate Professor in 2010 and Full Professor in 2014. In 2001 he received the Provost’s Award for Graduate Research at the University of Illinois at Chicago. In 2002, he was awarded a University Fellowship at the University of Illinois. He received an AFOSR Young Investigator Award in 2009. He became an Associate Fellow of AIAA in 2013. The research interests of Professor Jacobs can broadly be defined in the area of computational multiphase, and multiscale flow physics modeling and simulation using high-order methods. Emphasis is on simulation and analysis of particle-laden flows and flow separation in complex geometries, to aid flow control relating to combustion optimization and drag reduction.

Wednesday, February 16, 2022

3:30 PM

Zumberge Hall of Science, Room 252 (ZHS 252)

The Zoom webinar is at https://usc.zoom.us/j/93987337017?pwd=MWd2dXBSL1FaR1RPaHNscjJ1NW80UT09.

host: Spedding

Exterior Algebra and the Proportional Selective Modification of Dynamical Systems, from Rotors to Nonlinear Lattices

James Hanna

Associate Professor
Department of Mechanical Engineering
University of Nevada, Reno
Reno, NV

This is the story of a seemingly trivial problem, born of quarantine, that surprised me by turning into something more interesting. I will introduce a new technique for adding dissipation or otherwise modifying dynamical systems to selectively change any number of conserved quantities, while only reducing the total number of conserved quantities by one. I will first present a naïve approach to a simple example, a textbook problem of a specially damped rotor often used to explain the failure of the Explorer 1 satellite. Then (in joint work with M. Aureli), we generalize the approach to any number of dimensions and conserved quantities. The resulting dynamics drives the modified system to a nontrivial state of the original system.

James Hanna is Associate Professor in the department of Mechanical Engineering at the University of Nevada, Reno, which he joined in 2019 from Virginia Tech. A lapsed materials scientist, he spent several years impersonating a postdoctoral physicist at UMass Amherst, and currently performs mechanics without a license. He is interested in applications of geometry to theoretical and experimental classical mechanics, and is currently thinking about shell buckling, cable snapping, pseudomomentum and material symmetry, new formulations of elasticity, and a few other things.

Wednesday, February 23, 2022

3:30 PM

Zumberge Hall of Science, Room 252 (ZHS 252)

The Zoom webinar is at https://usc.zoom.us/j/93987337017?pwd=MWd2dXBSL1FaR1RPaHNscjJ1NW80UT09.

host: Plucinsky

Non-Equilibrium Behavior in Combustion, Planetary Atmospheres, and Compressible Flows

Michael Burke

Associate Professor
Mechanical Engineering Department
Columbia University
New York, NY

Chemically reacting flows are often interpreted and computed under the premise that all chemical species have a range of energies in their rotational and vibrational modes that are well described by the Boltzmann or thermal distribution at the local temperature. Of course, breakdown in this premise can occur naturally as a result of chemical reactions, light absorption, and/or shock waves. The manifestations of this breakdown on unimolecular reactions, where non-thermally distributed molecular ensembles dissociate, are well known to give rise to pressure-dependent reactions in combustion, photochemical reactions in the Earth’s atmosphere, and induction time lags in reactions following shock waves. By contrast, manifestations of non-equilibrium behavior on bimolecular reactions, where non-thermally distributed molecules react with other species, are generally less understood and historically less appreciated. Here, I describe three distinct tales of such non-equilibrium behavior across varied application domains. In particular, I present results from ab initio master equation calculations that shed light on previous hypotheses and experimental observations and reveal new processes involving non-equilibrium induced by chemistry in combustion, photons in the Earth’s atmosphere, and shock waves in compressible flows. Namely, the rovibrationally excited ephemeral complexes, formed from association of two molecules, with a third molecule give rise to a fourth, long-forgotten type of phenomenological reaction, involving three chemical reactants, that impacts macroscopic combustion behavior; the vibrationally excited complexes, formed upon photon absorption, collide with oxygen to produce radicals even for low photon energies in the Earth’s troposphere; and the rovibrationally cold molecular ensembles encountered following shock waves not only slow the reaction timescales but also change the main chemical pathways.

Michael Burke is an Associate Professor of Mechanical Engineering at Columbia University, where he also holds affiliate appointments in Chemical Engineering and the Data Science Institute. Prior to joining Columbia in 2014, Burke earned his Ph.D. in Mechanical and Aerospace Engineering in 2011 at Princeton University, where he was a Wallace Memorial Honorific Fellow, and he worked as a Director’s Postdoctoral Fellow in the Chemical Sciences and Engineering Division at Argonne National Laboratory. Burke is a recipient of the National Science Foundation’s CAREER award, the Combustion Institute’s Research Excellence Award, the Combustion Institute’s Hiroshi Tsuji Early Career Researcher Award, and the American Chemical Society’s PRF Doctoral New Investigator Award. His publications have been featured in the “News and Views” section of Nature Chemistry, selected as the Feature Article in Combustion and Flame, and chosen for the Distinguished Paper Award at the 31st International Symposium on Combustion. His research combines physics and data across multiple scales to unravel and predict outcomes of complex reacting systems in varied application domains with major emphases on theoretical chemistry of non-equilibrium processes, multiscale data-driven modeling, and high-throughput experiments selected by optimal design.

Wednesday, March 2, 2022

3:30 PM

Zumberge Hall of Science, Room 252 (ZHS 252)

The Zoom webinar is at https://usc.zoom.us/j/93987337017?pwd=MWd2dXBSL1FaR1RPaHNscjJ1NW80UT09.

host: Egolfopoulos

Data-Driven Discovery of Governing Equations with Deep Learning and Sparse Identification Techniques

Joseph Bakarji

Research Associate
Mechanical Engineering Department
University of Washington
Seattle, WA

Machine learning techniques promise to offer the ultimate form of automation, particularly when applied to computational modeling and simulation. As a consequence, the computational scientist's narrative now revolves around discovering physics directly from data, with as little assumptions about the underlying physical system as possible. I briefly go over the latest attempts to accomplish this goal and focus on my recent work in combining deep learning with sparse identification of differential equations. First, I show how probability distribution function (PDF) equations can be inferred from Monte Carlo simulations for coarse-graining and closure approximations. Second, I present our latest results on discovering dimensionless groups from data, using the Buckingham Pi theorem as a constraint. And third, I go over the deep delay autoencoder algorithm that reconstructs high dimensional models from partial measurements as motivated by Takens' embedding theorem. I finally highlight the limitations of these methods and propose a few directions for future research.

Joseph Bakarji is currently a postdoctoral fellow in the department of mechanical engineering at the University of Washington, working with Steven Brunton and Nathan Kutz. He received his PhD in 2020 from Stanford University where he developed multiscale stochastic models for granular materials and data-driven closure models for uncertainty quantification. Joseph received the Henry J. Ramey, Jr. and the Frank G. Miller fellowship awards in 2018 and 2020 respectively. His current research focuses on combining deep learning and sparse identification methods, to discover interpretable physical models in complex systems from data.

Wednesday, March 9, 2022

3:30 PM

Zumberge Hall of Science, Room 252 (ZHS 252)

The Zoom webinar is at https://usc.zoom.us/j/93987337017?pwd=MWd2dXBSL1FaR1RPaHNscjJ1NW80UT09.

host: Kanso

Status and Outlook for Controlled Fusion as a Firm Zero-Carbon Energy Source

George Tynan

Professor
Mechanical and Aerospace Engineering
UC San Diego
LaJolla, CA

Controlled fusion research has been pursued since the 1950s by most of the world's developed economies due to many attractive characteristics of this seemingly elusive technology. In 2021, inertial confinement fusion experiments at LLNL reached the threshold of fusion ignition while magnetic confinement experiments in the UK demonstrated that the ITER device nearing completion in France should, for the first time, produce a burning plasma in which fusion heating dominates the system. In parallel, a rapidly developing industry with $4B of private-sector funding has emerged and is pursuing a wide variety of approaches for controlled fusion. This talk will summarize the key elements of these developments, and sketch out the characteristics that fusion-based energy systems will need to demonstrate if they are to compete economically in the emerging zero-carbon energy system of the mid-century.

George Tynan studies the fundamental physics of turbulent transport in hot confined plasmas using both smaller scaled laboratory plasma devices as well as large scale fusion experiments located around the world. In addition, he is investigating how solid material surfaces interact with the boundary region of fusion plasmas, and how the materials are modified by that interaction. He is also interested in the larger issue of transitioning to a sustainable energy economy based upon a mixture of efficient end use technologies, large scale deployment of renewable energy sources, and incorporation of a new generation of nuclear technologies such as advanced fission and fusion reactor systems. He received his Ph.D. in 1991 from the Department of Mechanical, Aerospace, and Nuclear Engineering at the University of California, Los Angeles. He then spent several years studying the effect of sheared flows on plasma turbulence on experiments located in the Federal Republic of Germany and at Princeton Plasma Physics Laboratory, and worked in industry developing plasma sources for use in investigating the creation of submicron-scale semiconductor circuits. He joined the UCSD faculty in 1999 where he worked to establish a graduate program in plasma physics within the School of Engineering. He has served as Associate Vice Chancellor for Research, Associate Dean of Engineering, is co-founding Director of the UC San Diego Deep Decarbonization Initiative, and is currently Department Chair of Mechanical and Aerospace Engineering at the UC San Diego Jacobs School of Engineering.

Wednesday, March 23, 2022

3:30 PM

Zumberge Hall of Science, Room 252 (ZHS 252)

The Zoom webinar is at https://usc.zoom.us/j/93987337017?pwd=MWd2dXBSL1FaR1RPaHNscjJ1NW80UT09.

Computational Models of Cardiovascular Function

Shawn Shadden

Professor
Department of Mechanical Engineering
UC Berkeley
Berkeley, CA

Combining medical imaging and other forms of clinical data with first principles-, phenomenological- and/or statistical-based computational modeling has become an important avenue in cardiovascular research, including for disease diagnosis, treatment planning and scientific discovery. In this talk, I will provide some background on the field of computational modeling of cardiovascular biomechanics and will discuss some of our recent work focused on methods to improve personalization and efficiency of this modeling process. Namely, I will discuss developments on machine learning approaches to facilitate image-based model construction and parameterization, some of our work on reduced order modeling to facilitate efficient computation of common physical quantities of clinical importance, and where we might be headed.

Shawn Shadden is a Professor and Vice Chair of Mechanical Engineering at the University of California, Berkeley and a core member of the UCSF-UC Berkeley Graduate Program in Bioengineering. His research focuses on the computational modeling of cardiovascular biomechanics and the advancement of theoretical and numerical methods to quantify complex fluid flow. He is recipient of an NSF CAREER Award, a Bakar Faculty Fellow Award, Hellman Faculty Fellow Award, and the American Heart Association’s Established Investigator Award. His lab helps develop the SimVascular software platform, which is broadly used in the field of computational cardiovascular research.

Wednesday, March 30, 2022

3:30 PM

Zumberge Hall of Science, Room 252 (ZHS 252)

The Zoom webinar is at https://usc.zoom.us/j/93987337017?pwd=MWd2dXBSL1FaR1RPaHNscjJ1NW80UT09.

host: Pahlevan

Functional Interpretation for Transverse Arches of Human Foot

Shreyas Mandre

Associate Professor
Mathematics Institute
University of Warwick
Coventry, UK

Fossil record indicates that the emergence of arches in human ancestral feet coincided with a transition from an arboreal to a terrestrial lifestyle. Propulsive forces exerted during walking and running load the foot under bending, which is distinct from those experienced during arboreal locomotion. I will present mathematical models with varying levels of detail to illustrate a simple function of the transverse arch. Just as we curve a dollar bill in the transverse direction to stiffen it while inserting it in a vending machine, the transverse arch of the human foot stiffens it for bending deformations. A fundamental interplay of geometry and mechanics underlies this stiffening -- curvature couples the soft out-of-plane bending mode to the stiff in-plane stretching deformation. In addition to presenting a functional interpretation of the transverse arch of the foot, this study also indicates a classification of flat feet based on the skeletal geometry and mechanics.

Shreyas Mandre is an applied mathematician, an engineer, and a scientist.

Before moving to Warwick, he served as an Assistant Professor in the School of Engineering at Brown University from 2010 to 2019. He was also a Lecturer in Applied Mathematics at Harvard University. He received my Ph.D. in Mathematics from the University of British Columbia in 2006. His undergraduate education was in Mechanical Engineering from the Indian Institute of Technology Bombay followed by an M.S. from Northwestern University in the same subject.

His research spans continuum mechanics, biomechanics, and applied mathematics, with applications to biology and engineering.

Wednesday, January 6, 2022

3:30 PM

Zumberge Hall of Science, Room 252 (ZHS 252)

The Zoom webinar is at https://usc.zoom.us/j/93987337017?pwd=MWd2dXBSL1FaR1RPaHNscjJ1NW80UT09.

host: Kanso

Properties of Turbulent Channel Flow Similarity Solutions

Joseph Klewicki

Professor and Head of the School of Electrical, Mechanical and Infrastructure Engineering
Faculty of Engineering and IT
University of Melbourne
Parkville, Victoria, Australia

The notion of similarity solutions and their connection to the scaling problem in turbulent wall-flows are briefly introduced. Analytical evidence is then presented indicating that the flow in fully developed turbulent channel flow formally admits a similarity solution. High resolution direct numerical simulation (DNS) data are then used to investigate the properties of the similarity solutions for the mean velocity and Reynolds shear stress. The solutions and their associated similarity structure are used to generate a number of new results. These include a cogent specification for the both the inner and outer boundaries of the inertial sublayer and a variety of well-founded ways to estimate the key parameter ϕ_c at finite Reynolds number. Extensions of the analytical arguments by Klewicki et al. (Phys. Rev. E, 90, 2014, p. 063015) lend further support to their conjecture that at large Reynolds number ϕ_c → (1 + √5)/2, or equivalently, the von Karman constant is given by k = 2/(3 + √5). The primary non-rigorous aspects of the analysis are critiqued, and the connections between the channel solutions and those in the other canonical wall-flows are briefly discussed.

Joseph Klewicki is Head of the School of Electrical, Mechanical and Infrastructure ("EMI") Engineering in the Faculty of Engineering and IT at the University of Melbourne, Australia. He is also the Faculty Director of Infrastructure. He is a Fellow of the American Physical Society, the American Society of Mechanical Engineers, and the Australasian Fluid Mechanics Society. He is also a Distinguished Alumnus of the Michigan State University (MSU)'s Department of Mechanical Engineering, and received his BS (1983), MS (1985) and PhD (1989) degrees from MSU, Georgia Tech and MSU respectively. As a researcher, Professor Klewicki specializes in experimental methods in fluid mechanics, turbulent and unsteady flows, vorticity dynamics, boundary layers, and atmosphere surface layer phenomena. He conducts much of his research on the fluid dynamics of turbulent shear flows, with a special emphasis on wall-bounded turbulent flow and their Reynolds number scaling. This research involves both analytical and experimental studies, including the development of experimental methods, and involves other complex and turbulent flows. More recently, he has also begun to study phenomena specifically relevant to geophysical flows, namely those that include the effects of three-dimensionality, stratification, and rotation.

Thursday, April 14, 2022

10:00 AM

Laufer Conference Room (OHE 406)

host: Spedding