AEM Colloquium Series

About

The Department of Aerospace Engineering and Mechanics holds its colloquium on Fridays from 2:30 pm to 3:30 pm. Unless otherwise indicated, all lectures will take place in Rapson Hall 43 this semester. Please note some events may be subject to change. 

 

Spring 2025

 

Shaoshuai Mou, April 28, 2:30pm

Purdue University, School of Aeronautics and Astronautics

Title: A Tunable Control/Learning Framework for Autonomous Systems

Dr. Shaoshuai Mou

Abstract: Modern society has been relying more and more on engineering advance of autonomous systems, ranging from individual systems (such as a robotic arm for manufacturing, a self-driving car, or an autonomous vehicle for planetary exploration) to cooperative systems (such as a human-robot team, swarms of drones, etc). In this talk we will present our most recent progress in developing a fundamental framework for learning and control in autonomous systems. The framework comes from a differentiation of Pontryagin’s Maximum Principle and is able to provide a unified solution to three classes of learning/control tasks, i.e. adaptive autonomy, inverse optimization, and system identification. We will also present applications of this framework into human-robot teaming, especially in enabling an autonomous system to take guidance from human operators, which is usually sparse and vague. In addition, we will briefly introduce our recent progress in developing control methods for aerospace systems applications.

Bio: Dr. Shaoshuai Mou is the Elmer Bruhn associate professor in the School of Aeronautics and Astronautics at Purdue University. He received a Ph.D. in Electrical Engineering at Yale University in 2014, worked as a postdoc researcher at MIT for a year, and then joined Purdue University as a tenure-track assistant professor in Aug. 2015. His research group Autonomous & Intelligent Multi-agent Systems (AIMS) lab has been focusing on advancing control theories with recent progress in optimization, networks and learning to address fundamental challenges in autonomous systems, with particular research interests in multi-agent systems, control of autonomous systems, learning and adaptive systems, cybersecurity and resilience. Dr. Mou co-directs Purdue’s Institute for Control, Optimization and Networks (ICON) launched in 2020 consisting of 100 faculty from more than 15 departments across Purdue University.

 


 

 

Vikram Deshpande, April 11, 2:30pm

University of Cambridge, Department of Engineering

Title: Laboratory X-Ray Measurements in Solid Mechanics: Any New Insights?

Professor Vikram Deshpande

Abstract: A range of laboratory-based X-ray techniques ranging from energy dispersive X-ray diffraction to measure elastic strains in metals, high speed tomography of the dynamic deformation of architected solids to 3D deformation fields within rubbers will be discussed. Do these novel measurements provide any new insights into the mechanics of these materials? One example will be discussed in detail. From Hooke’s law in the 1660s to the 1930s work of Flory on polymer chains, the understanding of rubber elasticity was formalised via the Neo-Hookean model. This established the idea that, under isothermal conditions, stress is (non)linearly related to strain and no other state variable. Using innovative X-ray measurements capturing the three-dimensional spatial volumetric strain fields, we demonstrate that this idea may need to be revisited. We show that rubbers and indeed many common engineering polymers, undergo significant local volume changes. But remarkably the overall specimen volume remains constant regardless of the imposed loading. This strange behaviour, which also leads to apparent negative local bulk moduli, is due to the presence of a mobile phase within these materials. Using a combination of these tomographic observations and high-speed radiography to track the motion of the mobile phase we present a revision of the classical thermodynamic frameworks of rubber elasticity. 

Bio: Vikram Deshpande is a professor of Materials Engineering at the University of Cambridge. He has also served on the faculties at the University of California, Santa Barbara and at the Technical University of Eindhoven. With his students and collaborators, he has worked primarily in experimental and theoretical solid mechanics and currently serves as the editor-in-chief of the Journal of the Mechanics and Physics of Solids (JMPS). His recognitions include the 2020 Rodney Hill Prize in Solid Mechanics, the 2022 Prager Medal, the 2022 ASME Koiter medal and the 2024 Bazant medal ASCE. He has been elected Fellow of the Royal Society, London, the UK Royal Academy of Engineering, and an International Member of the US National Academy of Engineering (NAE). 

 


 

 

Jason Hearst, February 28, 2:30pm

Professor Jason Hearst

Norwegian University of Science and Technology (NTNU)

Title: The Complex Role of Turbulence: Vanishing Tip Vortices, Scattering Waves, and Enhanced Gas Transfer

Abstract: We will discuss three areas where recent advances in experimental turbulence measurements have led to new insights. First, time-resolved volumetric measurements of the wake of a model wind turbine are used to investigate the often observed phenomenon whereby vortices “vanish” rapidly downstream of a wind turbine. Moving to air-water interfacial flows, we investigate the interaction between surface waves and sub-surface turbulence, with a particular focus on enstrophy enhancement and wave scattering. Our results demonstrate that sub-surface turbulence can increase the rate of environmentally significant gas exchange (e.g., O₂, CO₂) across the air-water interface by up to 45%. The talk will also showcase recent advances in flow measurements, including the use of quantifiable laser-induced fluorescence to map O₂ concentration in water while simultaneously capturing the velocity field and surface topology. Additionally, we introduce a novel co-flowing air-water facility equipped with active turbulence grids in each phase, allowing for independent control of turbulence in the air and water.

Bio: Jason Hearst is a Professor at the Norwegian University of Science and Technology (NTNU) in Trondheim, Norway. His primary research activities are centred around the generation of bespoke turbulent flows using active turbulence generating grids and investigating how turbulence influences other canonical and environmental fluids problems. Most recently, focus has been placed on the gas-liquid (air-water) interface, where on-going studies focus on gas transfer processes at the air-water interface and how they are influenced by turbulence. Prof. Hearst’s team is primarily funded via the European Research Council (Starting Grant, GLITR), Marie Skłodowska-Curie Actions (Post-doctoral fellow, Dr. Yi Hui Tee, InMyWaves) and the Research Council of Norway (FRIPRO, WallMix; Knowledge Building Project, reSail). Jason Hearst was awarded his PhD in 2015 from the University of Toronto Institute for Aerospace Studies (Canada), and then worked as a post-doctoral researcher at the University of Southampton (UK) with Prof. Bharath Ganapathisubramani. He moved to NTNU in 2017 as an Associate Professor (1 st -tier of 2-tier Norwegian professor system) and was promoted to Professor (2 nd -tier of 2-tier Norwegian professor system) in 2023. He is presently on sabbatical at the University of Toronto until June 2025.

 


 

 

Qizhi (“KaiChi") He, January 31, 2:30pm

Professor QiZhi He

University of Minnesota, Department of Civil, Environmental, and Geo-Engineering

Title: Differentiable Computational Mechanics: Neural-Integrated and Data-Driven Modeling for Inelastic Solids and Geophysical Applications

Abstract: We present a recent development in the hybrid computational framework that integrates physics-based numerical schemes with machine learning methods to address various forward and inverse problems in computational mechanics. Our focus is on applications involving complex material behaviors and coupling effects, exploring how physical laws can be effectively incorporated within these methods across varying levels of data availability. We introduce a variationally consistent physics-informed machine learning approach, termed the Neural-Integrated Meshfree (NIM) method, designed to improve accuracy and training efficiency for simulating large deformations and material nonlinearities. To this end, the NIM method employs a hybrid approximation strategy that combines neural network representations with customized basis functions. The effectiveness of the NIM method is demonstrated through a series of linear and nonlinear benchmark mechanics problems, including applications in identifying heterogeneous biological materials. We also extend this framework to model Lagrangian particle flow problems, showcasing its potential to handle complex material behaviors under extreme conditions. Additionally, in data-rich scenarios, we introduce a hybrid scheme that leverages data-driven learning models for solving coupled systems. Our results show that the proposed machine learning models can reliably learn operators to capture underlying physical processes, enabling efficient dimensionality reduction. Examples from geophysics and biology will be presented to highlight the versatility of these machine learning techniques in advancing scientific computing.

Bio: Dr. Qizhi (“KaiChi") He is an Assistant Professor in the Department of Civil, Environmental, and Geo-Engineering at the University of Minnesota (UMN). He received his M.A. in Applied Mathematics (2016) and Ph.D. in Structural Engineering and Computational Science (2018) from the University of California, San Diego. From 2019 to 2021, he worked as a postdoctoral research associate in Scientific Machine Learning Group at Pacific Northwest National Laboratory. His research focuses on developing advanced numerical methods and physics-integrated machine learning algorithms to predict complex mechanics in porous and composite material systems under extreme conditions, as well as advancing inverse modeling and data assimilation for large-scale multi-physics applications in solid mechanics, material design, and geophysics. Dr. He is a member of the ASCE/EMI technical committees on Computational Mechanics and Machine Learning in Mechanics and serves on the editorial board of Computers and Geotechnics.

 


 

 

Michael Coughlin, January 24, 2:30pm

University of Minnesota, School of Physics and Astronomy

Michael Coughlin

Title: A Technical Ecosystem to Enable Multi-Messenger Astrophysics

Abstract: With the detection of compact binary coalescences and their electromagnetic counterparts by gravitational-wave detectors, a new era of multi-messenger astronomy has begun. In this talk, I will describe how current ground based optical surveys and dedicated follow-up systems are being used to identify more of these, and how we are developing models to test what we find. I will further describe the variety of technical challenges we currently face and ideas for what we might learn from optimization techniques more common in the aerospace field. We will close with near-term prospects for the field.

Bio: Michael Coughlin is an Assistant Professor in the School of Physics and Astronomy at the University of Minnesota. He received his M.A. in Astronomy from Cambridge University (2013) and his Ph.D. in Physics from Harvard University (2016). Coughlin's research focuses on using multi-messenger astronomy to study the Universe, coming at the same problem from multiple directions to gain a more complete picture. In particular, Coughlin studies the coalescence of binary neutron stars with both gravitational waves and electromagnetic data, predominantly using wide field-of-view optical telescopes such as the Zwicky Transient Facility (ZTF) to identify these counterparts. Coughlin also uses these telescopes to search for future sources from the Laser Interferometer Space Antenna (LISA), a space-based gravitational wave detector that will study white dwarf binaries in our galaxy as well as binary black hole mergers.

 

 

Fall 2024

 

Vargnese Mathai

Varghese Mathai, December 6, 2:30pm

University of Massachusetts, Amherst

Title: Bubbles and Elastic Membranes in Flows: From Hydrokinetic Energy Extraction to Turbulence Modulation

Abstract: The interaction of deformable materials with fluid flows can result in a variety of emergent phenomena, many of them advantageous in engineering. In this talk I will present two multiphase flow systems where interfacial mechanics contribute to enhancements in thermal and mechanical energy extraction from fluid flows. In the first part, I will discuss flow modifications that result from the introduction of a small fraction of millimetric bubbles in a turbulent flow. In the second part of the talk, I will discuss the fluid-structure interactions of a deformable (elastic) membrane in a uniform stream. I will show how an elastic membrane has many similarities to a bubble. We reveal the mechanisms by which the membrane’s elasticity, curvature and unsteady deformations could lead to an enhancement in hydrokinetic energy extraction or turbulence production in different contexts. Potential benefits of using ultra-soft materials for flow control and energy extraction will be outlined.

Bio: Varghese Mathai is an Assistant Professor in the Department of Physics and Department of Mechanical Engineering at the University of Massachusetts, Amherst. His group’s research interests are mainly on experimental bubbly and soft material-laden turbulent flows, and on the fluid mechanics of airborne transmission. Varghese’s research on elastic materials in turbulent flows is funded by an NSF CAREER award. His prior work has been selected for Best Research Prize in Flowing Matter by the European COST in 2019. His recent works on airborne transmission risks has been featured in the New York Times, the Washington post, and the American Institute of Physics, and appears in CDC’s guidelines for airborne transmission mitigation.

 

 


H.S. Udaykumar, November 22, 2:30pm

University of Iowa

Title: From a tiny spark to a massive explosion --  modeling the multi-scale physics of detonations of solids

Headshot of Professor Udaykumar

Abstract: Multi-scale modeling of energetic materials (propellants, explosives, and pyrotechnics) and their sensitivity requires telescoping physics from the nano- and micro- and meso-scales in order to make predictions of their macro-scale response. While atomistic simulations must inform meso-scale models, meso-scale models must provide closure to macro-scale simulations. This talk will highlight the physics at various scales that play a role in the cascade of events that leads from a tiny spark to a massive explosion. In particular, we focus on detonations in condensed phase energetic materials which are typically composites comprised of organic crystals, binders and additives (metals, plasticizers, etc). The state-of-the-art understanding of the physics and modeling of the multi-scale phenomena will be highlighted with special emphasis on the emerging multifarious roles of artificial intelligence in simulation and design of solid composite energetic materials.

Bio: Udaykumar is Roy J. Carver Professor of mechanical engineering and Associate Dean for research, graduate programs and faculty in the college of engineering at the University of Iowa. He received a BTech in Aerospace Engineering from the Indian Institute of Technology (Chennai) and MS and PhD degrees from the University of Florida. He has published over 150 journal papers in varied topic areas of biomedical and mechanical engineering. His research focus is on multi-scale modeling and simulation of a wide range of moving boundary problems in thermomechanical systems, ranging from phase change thermal storage, biomedical applications involving cardiovascular and gastrointestinal mechanics, energetic material dynamics in propulsion and munitions, and multiphase flows at all speeds. He has been supported by grants from NSF, Whitaker Foundation Biomedical Engineering Grant, NIH, VA Research grants and multiple concurrent grants from various DoD agencies.


Ibrahim Guven, November 15, 2:30pm

Virginia Commonwealth University

Title: Predicting Damage in Aerospace Structures Due to Adverse Weather Encounters

Headshot photo of Ibrahim Guven

Abstract: There is renewed interest in hypersonic flight with applications in defense and civilian aerospace. Nontrivial chances of weather encounters with airborne particles (raindrops, ice particulates, volcanic ash) exist at lower altitudes. Predicting structural damage due to raindrops at hypersonic velocities is an open problem owing to the complex multiphysics involved. This talk will first describe the physics of the high-speed droplet impact and then demonstrate a computational solid mechanics approach, peridynamics, for damage predictions. Droplet-shock layer interactions, coupling with computational fluid dynamics, 2D vs. 3D, and other relevant topics will be discussed. 

Bio: Ibrahim Guven is an Associate Professor of Mechanical and Nuclear Engineering at Virginia Commonwealth University (VCU). He was an Assistant Professor of Materials Science and Engineering at The University of Arizona. Ibrahim spent two summers as a Faculty Fellow at the Air Force Research Laboratory. He was a Visiting Professor at the University of Rennes I, France, multiple times. Ibrahim is a recipient of the NASA Group Achievement Award for "outstanding work in developing materials for space exploration," awarded to participants of the collaborative project he worked on: US-COMP Space Technologies Research Institute.


Brian Schipper, November 8, 2:30pm

Headshot of Brian Schipper

Honeywell

Title: Honeywell Alternate Navigation Research Overview

Abstract: We will discuss the current methods of GPS-denied (or Alternative) navigation currently being developed by Honeywell.  These include celestial navigation, vision aided navigation. Magnetic anomaly navigation, and LEO RF navigation.

Bio: Brian is currently a research fellow at Honeywell has 37 years of experience with navigation system research and development.  After focusing on GNSS technology, Brian has spent the last 8 years working on forms of navigation that could be used when GNSS is not available.


Raul Radovitzky, November 1, 2:30pm

Massachusetts Institute of Technology

Title: A unified framework for large-scale simulation of the thermo-chemo-mechanical response of thermal protection systems in hypersonic environments

Headshot photo of Raul Radovitzky

Abstract: I will present a thermo-chemo-mechanics computational framework for the analysis of material and structural degradation and failure resulting from extreme conditions encountered in hypersonic flight. The approach is based on a unified discontinuous-Galerkin finite-element formulation of the coupled equations describing the solid mechanics, heat transfer, mass transport, and chemical reaction problem. The resulting computational framework supports general models of thermo-chemical reactive transport (convection, diffusion, oxidation, pyrolysis), thermo-chemically-induced mechanical stresses and material fracture, and thermal and chemical diffusion resistance across crack surfaces, as well as surface ablation. We demonstrate the versatility of the computational framework with simulations of: 1) pyrolysis and ablation of Phenolic Impregnated Carbon Ablator (PICA) material, resulting in thermo-chemically induced mechanical stresses and surface recession, 2) thermally-induced oxidation, growth, and swelling stresses leading to fracture of silicon carbide. 

Bio: Raul Radovitzky is a Professor of Aeronautics and Astronautics at the Massachusetts Institute of Technology. He also serves as the Associate Director of the MIT Institute for Soldier Nanotechnologies. He received a Civil Engineer degree from the University of Buenos Aires in 1991, A S. M. in Applied Mathematics from Brown University in 1995 and a Ph D in Aero nautical Engineering from the California Institute of Technology in 1998. 

His research interests are in the development of computational methods for multi-scale modeling of complex material response as well as in the formulation and implementation of algorithms for large-scale simulation of the dynamic response of materials subject to hypersonic flight environments. His main emphasis is on the analysis of material and structural failure. His group has pioneered the development of massively-scalable algorithms for the simulation of dynamic fracture. The methods his group has developed have also led to significant advances in our understanding of the physical effects of blast waves on structures and on the human brain. This has helped to develop strategies to protect against Traumatic Brain Injury. 

As part of his devotion for education and student life, he and his wife Flavia have been the Heads of House at McCormick Hall, the only all-women dormitory at MIT, since 2015, where they have contributed to building a thriving community of young scholars. As a recognition of his dedication to students, he has received the following awards: The 2021 Arthur C. Smith Award, the 2014 Student Champion (Freshman Advising) Award, the 2016 AIAA Aeronautics and Astronautics Teaching Award, the 2018 Alan J. Lazarus (1953) Excellence in Advising Award, the 2021 AIAA Aeronautics and Astronautics Best Professor Award, and the 2021 Arthur C. Smith Award for meaningful contributions and devotion to undergraduate student life and learning at MIT. 

Dr. Radovitzky is an Associate Fellow of the American Institute of Aeronautics and Astronautics and a member of the National Football League Engineering Committee. 


Dr. James Scoggins, October 25, 2:30pm

Headshot photo of Scoggins

Title: Seeing the Light: How the Mars 2020 Radiometer Optics Influenced Perceived Signal Loss

Abstract: The Mars 2020 vehicle, carrying the Perseverance Rover and Ingenuity Helicopter, successfully landed on the Red Planet on February 18, 2021.  During its entry into the Martian atmosphere, an onboard sensor suite, dubbed MEDLI2, recorded an unprecedented number of surface pressures, in-depth temperatures, and total and radiative heat flux measurements in order to help NASA engineers reconstruct the aerothermodynamic environment surrounding the vehicle and provide a wealth of data for validating their numerical simulation tools.  In this talk, I will describe recent modeling of the on-board radiometer which improves our understanding of the radiation measurements from MEDLI2.  In particular, I will discuss how we constructed an optical model of the radiometer based on first principles, what insight the model provides for understanding the radiometer signal loss observed during flight, and how we can improve our calibration procedures in the future.

Bio: Dr. James Scoggins is a Research Aerospace Engineer in the Aerothermodynamics Branch of NASA Langley Research Center.  He has a Ph.D. in Aerospace Engineering jointly from the von Karman Institute for Fluid Dynamics in Brussels, Belgium, and CentralSupélec in Paris, France, with a thesis entitled "Development of numerical methods and study of coupled flow, radiation, and ablation phenomena for atmospheric entry."  Dr. Scoggins is the creator and main developer of the open-source library called Mutation++ which provides thermodynamic, transport, and kinetic data for ionized gases.  His current research interests include aerothermodynamics, machine learning, and multi-fidelity modeling approaches.


Cyril Williams, October 18, 2:30pm

Army Research Lab

Title: Structure-Property Relationships at the Extremes: Shock Compression of Condensed Matter

Abstract: The inelastic response and residual mechanical properties acquired from most shock compressed solids are quite different from those acquired from quasi-static or moderate strain rates. For instance, the residual hardness of many shock compressed metals has been found to be considerably lower than those loaded under quasi-static conditions to the same maximum stress. However, the residual hardness of shock compressed metals is much higher than those loaded quasi-statically to the same total strain. These observations suggest that the deformation mechanisms active during inelastic deformation under shock compression and quasi-static or moderate rates may be quite different. Therefore, the primary objective of this talk is to offer the audience a concise background on the structure-property relationships concerning shock loaded condensed matter via in-situ, end-state (recovery), and real-time X-ray diffraction shock experiments. Then elucidate the results derived from such experiments to develop a fundamental understanding of the residual mechanical properties, microstructure changes, and spall failure mechanisms in shock loaded materials with different crystal lattice structures such as 1100-O aluminum (fcc), AZ31B-H24 magnesium (hcp), fine grained AMX602 magnesium (hcp) nanocrystalline Copper-tantalum (fcc), and titanium diboride (hexagonal).

Bio: Cyril Williams is currently a Senior Research Engineer and the Army’s Subject Matter Expert (SME) in both in-situ (real-time) and ex-situ (end-state) gas gun shock experiments at the US Army Research Laboratory. Dr. Williams is interested in probing the nucleation and evolution of damage and consequent failure in materials subjected to extreme conditions. He earned his B.Sc. and M.Sc. in Mechanical Engineering (Fatigue and Fracture) from the University of Maryland Baltimore County, then M.S.E. and Ph.D. in Mechanical Engineering (Shock Compression Science) at The Johns Hopkins University. Dr. Williams is a Fellow of the American Society of Mechanical Engineers (ASME), Fellow of the American Society of Metals, Department of Defense LUCI Fellow, Federal Engineer of the Year (2015), and a licensed Professional Engineer in Delaware (#13160) and Maryland (#44307). He is currently the executive head of ASME Government Relations (Delaware Section), was a member of the American Physical Society (APS)-Shock Compression of Condensed Matter (SCCM) Executive Committee, and an active member of several engineering societies including the American Society of Mechanical Engineers (ASME), Society of Experimental Mechanics (SEM), The Minerals, Metals, and Materials Society (TMS), and Tau Beta
Pi Engineering Honors Society. He is currently a visiting research scientist at the Massachusetts Institute of Technology (2021-Present), and has given numerous invited talks nationally and internationally including University of Oxford, University of Cambridge (Cavendish Laboratory), California Institute of Technology, Massachusetts Institute of Technology, Johns Hopkins University, University of Alberta (Edmonton), and Imperial College London (Institute of Shock Physics).

*Refreshments to follow in Akerman 227


Professor Ryan Caverly, October 11, 2:30pm

Aerospace Engineering and Mechanics - University of Minnesota

Caverly_headshot crop

Title: Optimal and Robust Control: Theoretical Extensions, Robotics & Aerospace Applications, and the Development of Space Technology

Abstract: This talk will provide an overview of the research directed by Prof. Caverly in the Aerospace, Robotics, Dynamics, and Control (ARDC) Lab. In particular, the ARDC Lab's contributions will be highlighted in the areas of (1) the development of novel optimal & robust control theory and design methods for uncertain dynamic systems; (2) the application of estimation and control techniques to enable novel capabilities in aerospace and robotic systems; and (3) the development of new spacecraft technology, primarily inspired by robotic systems.

Bio: Ryan Caverly is an Assistant Professor and McKnight Land-Grant Professor in the Department of Aerospace Engineering and Mechanics at the University of Minnesota.  He received his B.Eng. degree in Honours Mechanical Engineering from McGill University, and his M.S. and Ph.D. degrees in Aerospace Engineering from the University of Michigan, Ann Arbor.  Prior to joining the University of Minnesota, he worked as an intern and then a consultant for Mitsubishi Electric Research Laboratories in Cambridge, MA.  His research interests include dynamic modeling and control systems, with a focus on robotic, mechanical, and aerospace applications, as well as robust and optimal control techniques.


Faculty Research: Solids, October 4, 2:30pm

Introduction to Solids Faculty

This Friday's seminar will give students a chance to get to know our Solid Mechanics Faculty!


Faculty Research: Fluids, September 27, 2:30pm

Introduction to Fluids Faculty

Friday's seminar will give students a chance to get to know our Aerospace Fluids Faculty!

 


Faculty Research: Systems, September 20th, 2:30pm

Introduction to Aerospace Systems Faculty

This Friday's seminar will give students a chance to get to know our Aerospace Systems Faculty!


Professor Rajat Mittal, September 13, 2:30pm

Midwest Mechanics Seminar

Mechanical Engineering - Johns Hopkins University

Title: Dissecting the Causality of Pressure Forces in Fluid Dynamics - From Vortex Induced Vibration and Fish Schools to Noisy Drones

Photo of Prof. Rajat Mittal

Abstract: Pressure-induced drag and lift are key to the performance of wings, rotors and propellers; undulating fins and flapping wings generate forces that are key to locomotion in fish, birds and insects; time-varying fluid dynamic forces drive flutter and flow-induced vibrations of flexible structures in engineering and biology, and these same forces enable the extraction of energy from flow via devices such as wind-turbines. Pressure on a body immersed in a flow is however induced simultaneously by vortices, acceleration reaction (a.k.a. added mass) effects associated with body and/or flow acceleration, and viscous diffusion of momentum, and determining the relative contribution of these different mechanisms on surface pressure remains one of the most important and fundamental issues in fluid dynamics. I will describe the force partitioning method (FPM), a new data-enabled method that partitions pressure forces into components due to vorticity, acceleration reaction and viscous diffusion. FPM has been used to gain new insights into a variety of vortex dominated flows including dynamic stall in pitching foils, vortex-induced vibration of bluff-bodies, hydrodynamics of schooling fish and rough-wall boundary layers, and results from these analyses will be presented. Application of FPM to data generated from experiments will also be described. Finally, FPM has been extended to aeroacoustics, and applications of the aeroacoustic partitioning method (APM) to aeroacoustic noise in engineering and biological flows will be presented.

Speaker Bio: Rajat Mittal is Professor of Mechanical Engineering at the Johns Hopkins University with a secondary appointment in the School of Medicine. He received the B. Tech. degree from the Indian Institute of Technology at Kanpur in 1989, the M.S degree in Aerospace Engineering from the University of Florida, and the Ph.D. degree in Applied Mechanics from The University of Illinois at Urbana-Champaign, in 1995. His research interests include computational fluid dynamics, vortex dominated flows, biomedical engineering, biological fluid dynamics, fluid-structure interaction, and flow control. He has published over 200 technical articles and multiple patents in these application areas. He is the recipient of the 1996 Francois Frenkiel and the 2022 Stanley Corrsin Awards from the Division of Fluid Dynamics of the American Physical Society, and the 2006 Lewis Moody as well as 2021 Freeman Scholar Awards from the American Society of Mechanical Engineers (ASME). He is a Fellow of ASME and the American Physical Society, and an Associate Fellow of the American Institute of Aeronautics and Astronautics. He is an associate editor of the Journal of Computational Physics, Frontiers of Computational Physiology and Medicine, and serves on the editorial boards of the International Journal for Numerical Methods in Biomedical Engineering, and Physics of Fluids.


Professor Perry Leo, September 6, 2:30pm

Perry Leo

Aerospace Engineering and Mechanics - University of Minnesota

About: The first meeting of the Fall 2024 Seminar Series (AEM 8000) will be a welcome speech from our department head, Professor Perry Leo.

Bio: Professor Leo studies phase transformation, pattern formation and material properties in complex, multiphase solids. Leo and his group use theoretical and numerical analysis to couple formation of microstructure in these materials to their properties, such as strength, fracture and fatigue resistance, and electrical and magnetic response. Leo’s work encompasses a range of materials, including composite materials, biological materials, metal alloys and liquid crystals.

 

Earlier Colloquium 

 

January 19

There will not be a seminar on Friday, Jan. 19th.

 


Sayan Biswas, January 26, 2:30pm

Assistant Professor, Mechanical Engineering - University of Minnesota

Title: Plasma in Energy Research

Abstract: Plasma Power Propulsion Laboratory (3P Lab) explores the enormous potential of plasmas, especially low-temperature plasmas, towards clean energy production, high-efficiency propulsion, and cleaner transportation. Plasma – ionized gases comprised of ions, electrons, excited species, etc., holds the key to our future energy and environment. Even though plasma research existed for more than a century, the recent technological innovations in power electronics and advanced manufacturing have opened the door to a new world for energy researchers. 3P Lab uses low-temperature, non-thermal plasmas as a tool to access unconventional pathways to produce energy that is inaccessible to conventional energy systems.

In this talk, Biswas will elucidate the utilization of plasmas in energy and propulsion, touching upon various applications. These include: a) plasma-assisted chemical reforming of hydrocarbon fuels for cleaner combustion and control of combustion instability, b) the impact of plasma discharge on the breakup of a liquid jet in supersonic crossflow, c) laser-induced plasma and air shock from energetic materials to develop tailored innovative solid energetic propellants. The talk will conclude by exploring ideas on how plasmas can play an important role in supersonic aviation and reaction control processes.

Bio: Dr. Sayan Biswas is an Assistant Professor in Mechanical Engineering at the University of Minnesota Twin Cities. Previously, he was a postdoctoral researcher at Sandia National Laboratories’ Combustion Research Facility. Sayan earned a Ph.D. in Aerospace Engineering from Purdue University in 2017. He received masters from the University of Connecticut in 2012 and bachelors from Jadavpur University, India, in 2010, both in Mechanical Engineering. At the University of Minnesota, Sayan leads Plasma Power Propulsion Laboratory – 3P Lab, developing innovative and sustainable technologies for clean and efficient future energy. His research utilizes low-temperature plasmas in next generation of engines, discovers carbon-neutral E-fuels for aviation and transportation, and studies the fundamentals of high-speed propulsion.


Thea Feyereisen, February 2, 2:30pm

Thea Feyereisen

Sr. Fellow, Human Factors, Honeywell Aerospace Technologies 

Title: Designing Flight Deck Displays

Abstract: Cross-discipline teams and iterative design are key to innovations that improve safety and efficiency on the flight deck. The talk will discuss the R&D leading to two new flight deck features: Synthetic Vision Systems (SVS) and Runway Overrun Awareness Alerting Systems (ROAAS); and one yet to be certified: Runway Traffic Surface Alerting (Surf-A). Limitations and opportunities for technology introduction that improve operation efficiency and safety on the flight deck will be discussed.

 


Nicholaus Parziale, February 9, 2:30pm

Parziale

Associate Professor, Charles V. Schaefer, Jr. School of Engineering and Science - Department of Mechanical Engineering, Stevens Institute of Technology

Title: Hypersonic Turbulence Measurement and Observations of Drop Aerobreakup and Impact

Abstract: Reacting/high-speed flow investigation with non-intrusive optical techniques permits researchers to probe fluid flows in harsh or otherwise previously inaccessible environments. New insight into the flow physics of the problems in supersonic and hypersonic flows can be had with the clever application of recent advances in laser, camera, and electronics technologies. In this talk, two examples of such efforts will be discussed. First, new data on hypersonic turbulence with tagging velocimetry will be presented. Then, new drop aerobreakup and impact data pertaining to the multiphase flow in high-speed-vehicle/weather interactions will be presented.

 


Diane Davis, February 16, 2:30pm

Davis, Diane C.

Mission Design Lead for Gateway Systems Engineering and Integration

Title: Jettison and Disposal from the Lunar Gateway

Abstract:  The Gateway at the Moon will be the next human outpost in space: a proving ground for deep space technologies and a staging location for missions to the lunar surface and beyond. With crew visits every year, the Gateway will be constructed over time as various components arrive with Orion or are sent independently without crew presence. Naturally, spacecraft and objects of various descriptions will also depart the Gateway for other destinations. Examples include Orion carrying the crew back to Earth, cubesats deployed to locations in cislunar space, discarded logistics modules or lunar landers headed to heliocentric space, and the Gateway itself when its lifetime is complete. Each departing object must depart the vicinity of the Moon without risking collision with the Gateway or other spacecraft in the vicinity, and it must be delivered safely to its selected destination despite unavoidable operational errors and uncertainties. Each departure is governed by the dynamics of the Gateway orbit and the cislunar environment.

The Gateway orbit is a southern 9:2 Near Rectilinear Halo Orbit (NRHO) near the Moon. This NRHO is nearly
stable, but over time, any unmaintained object in this orbit departs due to small instabilities. A jettison maneuver
speeds the departure from the NRHO, but the effects of the maneuver on the spacecraft behavior depend on the
location, magnitude, and direction of the burn. The chaotic nature of the dynamics in cislunar space complicates the selection of a jettison maneuver to achieve a desired final destination. In this presentation, the challenges associated with deployment from the Gateway are discussed, and visual methods are used to overcome these difficulties and successfully design safe, effective departure trajectories from the Gateway halo orbit.

Bio: Dr. Diane Davis is the Mission Design lead for the Gateway Program at Johnson Space Center. She has a BS in Physics from Texas A&M University, an MS in Astrodynamics from the University of Texas at Austin, and a PhD in multibody astrodynamics from Purdue University. Previously, Diane worked in the inner planet navigation group at JPL and for mission control ground system development at JSC. Her research focuses on orbit maintenance and dynamics of departing flow in Near Rectilinear Halo Orbits.   Diane is a member of the American Astronautical Society Spaceflight Mechanics Committee and the International Astronautical Federation Astrodynamics Committee, and she is an AIAA Associate Fellow.


***CANCELLED***

Raul Radovitzky, February 23, 2:30pm

Professor, Department of Aeronautics and Astronautics  Associate Director, Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology

Title: A unified framework for large-scale simulation of the thermo-chemo-mechanical response of Thermal Protection systems in hypersonic environments

Abstract:  I will present a thermo-chemo-mechanics computational framework for the analysis of material and structural degradation and failure resulting from extreme conditions encountered in hypersonic flight. The
approach is based on a unified discontinuous-Galerkin finite-element formulation of the coupled equations describing the solid mechanics, heat transfer, mass transport, and chemical reaction problem. The resulting computational framework supports general models of thermo-chemical reactive transport (convection, diffusion, oxidation, pyrolysis), thermo-chemically-induced mechanical stresses and material fracture, and thermal and chemical diffusion resistance across crack surfaces, as well as surface ablation. We demonstrate the versatility of the computational framework with simulations of: 1) pyrolysis and ablation of Phenolic- Impregnated Carbon Ablator (PICA) material, resulting in thermo-chemically induced mechanical stresses and surface recession, 2) thermally-induced oxidation, growth, and swelling stresses leading to fracture of silicon carbide.

 

 


Dr. Jack Berkery, March 1, 2:30 pm

berkery_jack

Deputy Director, NSTX-U Research Program, Princeton Plasma Physics Laboratory -  U.S. Department of Energy

Title: The National Spherical Torus Experiment Upgrade – Advancing the Physics of Fusion Energy

Abstract: The National Spherical Torus Experiment (NSTX) at the Princeton Plasma Physics Laboratory has provided much of the physics basis for the spherical tokamak (ST) magnetic plasma confinement concept for fusion energy production; concepts which are currently being designed for future fusion pilot plants. NSTX is currently in the midst of an upgrade, and researchers are continuing to advance the physics understanding of ST plasmas to maximize the benefit that will be gained when the upgraded device (NSTX-U) returns to operation and to increase confidence in projections to future devices. STs have certain advantages: their more compact size (than conventional tokamaks) means they can provide higher plasma current more economically. Their low aspect ratio, of minor to major radius, improves stability with favorable average magnetic curvature, enabling high beta (the ratio of plasma pressure to magnetic pressure). There are challenges as well: managing high heat flux, and start-up and sustainment of the plasma without space for an induction coil. The objectives of NSTX-U research are to: (i) to extend particle confinement physics of low aspect ratio, high beta plasmas to the lower particle collisionality levels relevant to future device regimes, (ii) to develop stable, non-inductive scenarios with the self-generated current needed for steady-state operation, and (iii) to develop power and particle handling techniques to optimize plasma exhaust in high performance scenarios.


Christoph Brehm, March 15, 2:30pm

Associate Professor, Department of Aerospace Engineering - University of Maryland

Christoph Brehm

Title: A brief history of the Immersed Boundary Method - From blood flow to high Reynolds number aerospace applications 

Abstract: Since its inception in the early 1970s, the Immersed Boundary Method (IBM), initially introduced by Peskin to analyze blood flow in the heart, has evolved significantly, spawning thousands of studies across diverse applications. Originally designed to eliminate the time-consuming grid generation process and facilitate fluid-structure interaction simulations, IBM was initially perceived as a niche computational fluid dynamics (CFD) technique, best suited for low Reynolds number or “inviscid” flow scenarios. However, recent advancements have vastly expanded its applicability. This presentation traces the evolution of the IBM from its pioneering days to its current status, initially highlighting the development of advanced numerical schemes to improve the accuracy and stability characteristics of this method. The recent integration with Wall-Modeled Large Eddy Simulation (WMLES) and leveraging of modern compute platforms have further extended its applicability to high Reynolds number flow scenarios pertinent to aerospace applications. Drawing on 15 years of firsthand experience, from blood flow simulations to aerospace applications including rocket launches, the presenter will demonstrate IBM's impact on the field. The discussion will conclude with an assessment of IBM's readiness for industrial aerospace applications and an overview of remaining challenges. This journey through IBM's history and advancements underscores its transformation into a vital tool for complex flow simulations.

Bio: Dr. Brehm is an Associate Professor in the Aerospace Engineering Department of the University of Maryland. Previously, he was employed at the University of Kentucky (2012-2016) and before that he was a senior research scientist for the Science Technology Corporation at the Advanced Supercomputing Division at NASA Ames Research Center from 2012 to 2016. He was one of the main developers of the Launch Ascent and Vehicle Aerodynamics (LAVA) solver framework and employed LAVA to study a wide range of unsteady fluid dynamics problems, such as rocket launch site, contra-rotating open rotor, jet impingement, etc. His current research is at the intersection of fundamental numerical methods development and large-scale multi-physics applications. His most recent research efforts have focused on simulating and analyzing transitional and turbulent flows in low and high-speed regimes for fundamental studies in laminar-turbulent transition, turbulence, relaminarization, acoustics, and fluid-structure interaction.


Mukul Kumar, March 22, 2:30pm

 Mukul Kumar

Lawrence Livermore National Laboratory

Title: Assessing the design space for architected materials in extreme loading scenarios

Abstract: Owing to the tunability of mechanical response for structural applications, additively manufactured lattice structures are increasingly being studied to elucidate their response to static and dynamic loads. However, these roles are typically in opposition: static loads must be supported sufficiently far away from the onset of buckling or yielding, whereas dynamic loads are typically ameliorated by crushing of the lattice, which provides excellent energy-absorption due to the large plastic deformation accompanying densification. Moreover, emergent behavior, such as material jetting and elastic wave propagation, arising from the open architecture has been observed in situ under dynamic loading conditions. In this work we will outline a design scheme for lattice structures that must simultaneously support static loads while enduring high- amplitude impulsive loads. For a class of impulse shapes associated with laser-based shock compression, our key findings show that the static and dynamic responses of the lattice can be uncoupled and linked by a strength model that accounts for variability in the additive manufacturing process. Moreover, costly global search optimization can be replaced by sequential one-dimensional optimization following the direction of the wave propagating through the lattice. The design rules developed in this study expand the domain of applicability of lattice structures to challenging dual-loading regimes spanning decades of strain rates.

Bio: MUKUL KUMAR is a Distinguished Member of Technical Staff at Lawrence Livermore National Laboratory. Since joining LLNL in 1998 he has worked in the emerging areas of grain boundary engineering and orientation microscopy. He and his colleagues developed the concept of grain boundary network crystallography and its influence on fracture behavior in extreme environments. The seminal publications on grain boundary properties and long-range crystallographic correlations in materials microstructure are some of the most cited in the field. Concurrently, Mukul‘s research significantly improved our understanding of how microstructure influences dynamic failure and fracture, critical to defense applications design. The work of his team using in situ x-ray imaging methods has opened new avenues in our understanding of the dynamic compression response of architected materials and composites. He is currently a principal investigator on multiple weapons physics related projects and affiliated with the Institute for Shock Physics at Washington State University as an adjunct professor.


Ognjen Ilic, March 29, 2:30pm

Assistant Professor, Mechanical Engineering, Graduate Faculty Member: Electrical and Computer Engineering, School of Physics and Astronomy, University of Minnesota 

Ognjen Ilic

Title: Manipulating the Energy and the Momentum of Waves at the Subwavelength Scale

 Abstract: The transport of waves, such as light and sound, can be radically transformed when waves interact with metamaterial structures with engineered subwavelength features. My group focuses on understanding and developing electromagnetic and acoustic metamaterials to manipulate wave-matter interactions in ways not possible with conventional materials. I will discuss two examples from our work. First, we develop adaptive photonic metamaterials that can control emission and absorption of light for applications in spectral camouflage and space thermal management. Second, we explore how metamaterials can steer the momentum of waves to move objects without contact. This versatile concept enables new actuation functions, from ultrasonic guiding and tractor beaming to macroscale optical levitation and long-range actuation. These concepts could bring about ultralightweight and multi-functional structures and coatings with unique new terrestrial and space applications.

Bio: Ognjen Ilic is a Benjamin Mayhugh Assistant Professor of Mechanical Engineering at the University of Minnesota, Twin Cities. He completed his Ph.D. in physics at MIT and was a postdoctoral scholar in applied physics and materials science at Caltech. His research themes encompass light-matter and wave-matter interactions in nanoscale and metamaterial structures. He received the Air Force Office of Scientific Research (AFOSR) Young Investigator Award, the 3M Non-Tenured Faculty Award, the Bulletin Prize of the Materials Research Society, and a University of Minnesota McKnight Land-Grant Professorship. He holds courtesy appointments in the Department of Electrical and Computer Engineering and the School of Physics and Astronomy at the University of Minnesota.


Dan Henningson - MMS, April 12, 2:30pm

Henningson

Professor, KTH Royal Institute of Technology

Title: Large-scale numerical experiments of unsteady aerodynamic flows and the role of laminar-turbulent transition

Abstract: Fluid flows subject to time-dependent external forces or boundary conditions are ubiquitous in aeronautical applications. Whether one considers pitching wings, dynamic stall or the gust response of wind turbines, the flow is unsteady or non-autonomous. We investigate the influence of unsteadiness on the non-linear flow evolution, as well as on the linear response to small disturbances that determines their stability and the subsequent transition to turbulence. The simulations are performed with a high-order spectral-element method (SEM) with the domain discretized by up to several billion grid points. The capabilities of our SEM solvers are presented and two flow cases are studied in more detail. First, a small amplitude pitching wing where the laminar-turbulent interface drastically changes its cordwise location, and subsequently the dynamic stall of an airfoil undergoing a large pitchup motion.

We assess the potential of the optimally time-dependent (OTD) framework for transient linear stability
analysis of flows with arbitrary time-dependence using a localized linear/non-linear implementation.
This framework is first tried on oscillating plane Poiseuille flow to show the potential of the method
and subsequently used to track the linear stability of laminar separation bubbles on unsteady wings.
For the pitching case the global mode corresponding to an absolute local instability is identified at the
rear of the separation bubble, causing its breakdown to turbulence.

Bio: Dan Henningson is Professor of Fluid Mechanics at KTH Royal Institute of Technology since 1999, where he also obtained his PhD in 1988. Earlier he held positions as Assistant Professor of Applied Mathematics at MIT and as Senior Researcher at the Aeronautical Research Institute of Sweden. At present he is also holding an Endowed Professor Chair at Instituto Tecnológico de Aeronáutica, Brazil, in Honor of Peter Wallenberg Sr. Professor Henningson has made contributions to the areas of large-scale numerical simulation of laminar turbulent transition and its control, in particular so-called bypass transition in boundary layers under free stream turbulence, and more recently in the area of unsteady aerodynamics flows. His early theoretical work is summarized in the highly cited Springer monograph, Stability and Transition in Shear Flows, where the work on transient growth and non-normal effects in the laminar-turbulent transition process was highlighted. Professor Henningson has been instrumental in creating a number of excellent research environments, in particular as the
founding Director of the Linné FLOW Center, the Swedish e-Science Research Center and the Swedish Aerospace Research Center. Professor Henningson is the recipient of the prestigious Humbolt Prize and a European Research Council Advanced Grant. He is also an American Physical Society and EUROMECH Fellow as well as a member of the Royal Swedish Academy of Engineering Sciences.


Lauren Konitzer, April 19, 2:30pm

Konitzer, Lauren

NASA Goddard Space Flight Center

Title: Lunar Navigation Using GNSS Signals: The LuGRE Mission to the Moon

Abstract: NASA’s 2020 Artemis Plan specifically names GPS-based navigation as a means for meeting the unique needs of lunar explorers in the near future. GNSS is deliberately highlighted because while future lunar missions will surely utilize a multi-faceted lunar-based navigation framework, users can already obtain precise position, navigation, and timing (PNT) services with relatively low burden to size, weight, power, and cost by leveraging the existing and well-proven GNSS architecture around the Earth.

However, flight demonstrations are crucial for proving the feasibility of cislunar GNSS and laying the groundwork for future development of cislunar PNT technology. In order to achieve this goal, the Lunar GNSS Receiver Experiment (LuGRE) was conceived as a joint NASA-Italian Space Agency flight demonstration payload. LuGRE will fly onboard the Firefly Blue Ghost Mission 1 (BGM1) lunar lander to demonstrate multi-GNSS based position, navigation, and timing (PNT) in cislunar space and at the Moon. Launching in 2024, the LuGRE mission aims to receive GPS and Galileo signals at the Moon to characterize the lunar GNSS signal environment, demonstrate navigation and time estimation, and utilize collected data to support development of GNSS receivers specific to lunar use.

Bio: Lauren Konitzer obtained a Bachelors in Physics and a Bachelor in Aerospace Engineering and Mechanics in 2017, and a Masters in Aerospace Engineering and Mechanics in 2019, all at the University of Minnesota - Twin Cities.  Lauren is now a Navigation and Mission Design engineer at NASA Goddard Space Flight Center. She is the deputy principal investigator for the Lunar GNSS Receiver Experiment launching to the moon in 2024, and a flight dynamics analyst for the Roman Space Telescope, launching to Sun-Earth L2 in 2026.


Justin Wilkerson, April 26, 2:30pm

Associate Professor, Mechanical Engineering - Texas A & M University

Justin Wilkerson

Title: Microstructure-sensitive models for ballistic performance

Abstract:  Over the past five decades there has been an intense effort to understand and control the thermomechanical response of materials in extreme environments. A number of technologies critical to our safety and well-being stand to benefit from such understanding including armor and defense systems, next-generation fission and fusion reactors, spacecraft shielding, vehicular crashworthiness, and advanced manufacturing. Materials in such extreme environments often exhibit complex, somewhat non-intuitive mechanical behavior that is difficult to predict with empirical or phenomenological models. Here we discuss our development of a number of multiscale, mechanism-based models that help unravel this inherent complexity. This seminar will focus primarily on the development of an atomistically-informed crystal plasticity framework for deformation and failure of shock compressed single crystals and polycrystals. We further utilize this multiscale modeling framework to provide key insights into the development of reduced-order models, which are helpful in guiding the microstructural design of advanced light-weight armor and shielding materials. 

Bio: Professor Wilkerson’s research and teaching interests lie at the interface of solid mechanics, material science, and physics. He is particularly interested in the mechanical behavior of materials under the extreme conditions generated in armor and defense applications, nuclear reactors, hypersonic aircraft, rocket motors, as well as the cores and surfaces of planets and asteroids.

Wilkerson is an associate professor and James J. Cain Faculty Fellow in the J. Mike Walker ’66 Department of Mechanical Engineering at Texas A&M University. Wilkerson spent one year as a visiting Donald D. Harrington Faculty Fellow with the Department of Aerospace Engineering and Engineering Mechanics at the University of Texas at Austin. Prior to that, he was an assistant professor in the Department of Mechanical Engineering at the University of Texas at San Antonio. Wilkerson obtained his B.S. in Aerospace Engineering from Texas A&M, followed by an M.S.E and Ph.D. in Mechanical Engineering from Johns Hopkins University.

Wilkerson’s academic achievements have been recognized and supported by a number of honors and awards, including the NSF CAREER Award, AFOSR Young Investigator (YIP) Award, the Ralph E. Powe Junior Faculty Award, a Haythornwaite Foundation Research Initiation Award, and the Ammon S. Andes Award.