Abstract

I will first present a portable setup to generate shock waves using the exploding wire technique. Subsequently, I will showcase how droplets of various kinds (liquid metal, water, and polymeric liquids) interact and breakup in the shock wave and associated flow. I will also show the various instabilities that develop prior to breakup that are universal in nature. Lastly, I will showcase some results on shock-droplet flame interactions with analyses on flame extinction and droplet breakup.

Biographical Sketch

Prof. Saptarshi Basu received his PhD in Mechanical Engineering from University of Connecticut in 2007 with Prof. B. M Cetegen before joining University of Central Florida as an Assistant Professor. In 2010, he relocated to India and joined the prestigious Indian Institute of Science in Bangalore where he is currently the Pratt and Whitney Chair Professor in the Department of Mechanical Engineering.

Prof. Basu primarily works on multiphase systems, especially droplets at multiple length and timescales across multiple application domains ranging from surface patterning to combustion. Recently Prof. Basu have done extensive research on transmission of aerosols during COVID and on the efficacy of facemasks. His research marries fundamental aspects of classical fluid mechanics like vortex dynamics and swirling flows and the more interdisciplinary aspects of interfacial transport as in droplets to offer unprecedented insights into multiphase systems.

He is a fellow of Indian National Academy of Engineering, ASME, Institute of Physics, Royal Aeronautical Society and Royal Society of Chemistry. Prof. Basu is the recipient of DST Swarnajayanti Fellowship (equivalent of PECASE) in Engineering. Prof. Basu is a co-founder of a Biotech startup specializing in AI based Point of Care Diagnostics and a technical advisor to a deep tech startup involved in micro gas turbines. Prof. Basu serves as an editor/guest editor of several journals like Nature-scientific reports, Experiments in Fluids and European Physical Journal Special Topics. Prof. Basu’s research is extensively funded by Department of Defence, Indian Space Research Organization, Department of Science and Technology, Indo-German Science and Technology Center, Indo-US Clean Energy Center, NSF and industries like Siemens and Tata Motors. Prof. Basu has guided more than 20 PhD students in his career and published over 200 journal articles including many in Journal of Fluid Mechanics, Physics of Fluids, Combustion & Flame, Langmuir, Proc. Roy. Soc. etc.

Abstract: Advances in electrical energy storage systems are critical for vehicle electrification, renewable energy integration into the electric grid, and electric aviation. Recent years have witnessed an urgent need to accelerate innovation toward realizing improved and safe utilization of high energy and power densities, for example, in lithium-ion and advanced battery chemistries. These are complex, dynamical systems that include coupled processes encompassing electronic, ionic, and solid-state diffusive transport, electrochemical reactions at electrode/electrolyte interfaces, mechanical stress generation, and thermal transport in porous electrodes. This presentation will highlight the importance of the underlying mechanistic interactions at scale in the design of novel paradigms in exemplar energy storage architectures.

Biographical Sketch: Partha P. Mukherjee is a Professor of Mechanical Engineering and a University Faculty Scholar at Purdue University. His prior appointments include Assistant Professor and Morris E. Foster Faculty Fellow of Mechanical Engineering at Texas A&M University (2012-2017), Staff Scientist at Oak Ridge National Laboratory (2009-2011), Director’s Research Fellow at Los Alamos National Laboratory (2008-2009), and Engineer at Fluent India (currently Ansys Inc., 1999-2003). He received his Ph.D. in Mechanical Engineering from Pennsylvania State University in 2007. His awards include Scialog Fellows’ recognition for advanced energy storage, University Faculty Scholar and Faculty Excellence for Early Career Research awards from Purdue University, The Minerals, Metals & Materials Society Young Leaders Award, and invited presentations at the U.S. National Academy of Engineering Frontiers of Engineering symposium and Gordon Research Conference – Batteries, to name a few. His research interests are focused on mesoscale physics and stochastics of transport, chemistry, and materials interactions, including an emphasis on the broad spectrum of energy storage and conversion.

Abstract: The characterization and quantification of the coupling between flow and flexible structures and dominant oscillation modes remain open problems. Environmental science, energy, structural design, and locomotion applications require a comprehensive understanding of these phenomena. Canopy flows, encompassing extensive arrays of rigid or flexible structures, hold significant interest. Ubiquitous in natural environments and spanning multiple scales, they are instrumental in the transport of scalar and inertial particles. This presentation will provide insights from both theoretical perspectives and controlled laboratory experiments. I will discuss the role of key parameters modulating the unsteady dynamics of flows, individual structures, and canopies. These parameters comprise flow velocity, turbulence, structural stiffness, aspect ratio, tip effects, layout, and submergence within open channel flows. For this purpose, I will present data from particle image velocimetry (PIV), particle tracking velocimetry (PTV), and force balance analyses, highlighting turbulence, motion patterns, and unsteady loads on selected structures.

Biographical Sketch: Dr. Chamorro is an Associate professor in the Department of Mechanical Science and Engineering at the University of Illinois at Urbana-Champaign and is affiliated with the Departments of Aerospace Engineering, Civil and Environmental Engineering, and Geology. His research interests include turbulence, particle dynamics, boundary layer processes, aerodynamics, turbulence and structure interaction, wind energy, marine and hydrokinetic energies, and the development of advanced flow diagnostics. He has published 135 peer-reviewed articles in leading journals, has participated in over 140 presentations in technical symposia, and serves as scientific chair on Energy, Electrical Eng, Electronics and Mechanics (W&T7) at the Research Foundation Flanders (FWO) in Belgium. Chamorro is Associate Editor of the Journal of Renewable and Sustainable Energy, the Journal Frontiers in Energy Research, and the Journal of Energy Engineering. He leads the Renewable Energy and Turbulent Environment group, which uses a versatile experimental approach that combines state-of-the-art techniques, including 2D/3D particle image velocimetry, computer vision, and 3D particle tracking velocimetry.

Abstract: Deep learning approaches have become crucial tools across numerous engineering domains. However, they face various challenges, as they typically depend on representative data and large training datasets. Conversely, condition monitoring data for complex systems often lacks labels and representativeness, posing significant challenges for purely data-driven approaches. Additionally, deep learning models generally struggle in extrapolation regimes, which are common for assets characterized by long service lives and the frequent emergence of new operating regimes. 

In response to these challenges, the integration of physical laws and principles with deep learning methodologies has shown tremendous promise. This presentation will explore a variety of approaches that combine physics-based concepts with deep learning techniques. One focus will be on how incorporating structural inductive biases into learning architectures, such as through physics-enhanced graph neural networks, can address the aforementioned challenges.

To close the loop and bridge machine learning with physics, the talk will delve into novel approaches of symbolic regression through reinforcement learning to uncover symbolic equations.

Biographical Sketch: Olga Fink has been assistant professor of Intelligent Maintenance and Operations Systems at EPFL since March 2022.  Olga’s research focuses on Hybrid Algorithms Fusing Physics-Based Models and Deep Learning Algorithms, Hybrid Operational Digital Twins, Transfer Learning, Self-Supervised Learning, Deep Reinforcement Learning and Multi-Agent Systems for Intelligent Maintenance and Operations of Infrastructure and Complex Assets.

Before joining EPFL faculty, Olga was assistant professor of intelligent maintenance systems at ETH Zurich from 2018 to 2022, being awarded the prestigious professorship grant of the Swiss National Science Foundation (SNSF). Between 2014 and 2018 she was heading the research group “Smart Maintenance” at the Zurich University of Applied Sciences (ZHAW).

Olga received her Ph.D. degree from ETH Zurich with the thesis on “Failure and Degradation Prediction by Artificial Neural Networks: Applications to Railway Systems”, and Diploma degree in industrial engineering from Hamburg University of Technology. She has gained valuable industrial experience as reliability engineer with Stadler Bussnang AG and as reliability and maintenance expert with Pöyry Switzerland Ltd.

Olga has been a member of the BRIDGE Proof of Concept evaluation panel since 2023. Moreover, Olga is serving as an editorial board member of several prestigious journals, including Mechanical Systems and Signal Processing, Engineering Applications of Artificial Intelligence, Reliability Engineering and System Safety and IEEE Sensors Journal.

In 2018, Olga was honored as one of the “Top 100 Women in Business, Switzerland”. Additionally, in 2019, earned the distinction of being recognized as a young scientist of the World Economic Forum. In 2020 and 2021, she was honored r as a young scientist of the World Laureate Forum. In 2023, she was distinguished as a fellow by the Prognostics and Health Management Society.

Abstract: Water management is one of the most critical issues in proton exchange membrane fuel cells (PEMFCs). The water generated in catalyst layer as a product of the electrochemical reaction is mainly transported through porous media by diffusion if it’s vapor, or by capillarity in case of liquid. In flow channels, the liquid water is removed primarily by inertial force of the gas flows. In my research group (Multiscale Transport Process Laboratory) at Michigan Technological University, one of our focused research areas is the gas-liquid two-phase transport processes in PEMFCs.

In various aspects of the two-phase transport phenomena, this presentation is focused on the impact of land-channel geometry. If we look at the cross-section of PEMFC, land-channel geometry causes the difference in transport distance between the flow channel to the catalyst layer, and results in the uneven distribution of various factors, such as transport resistance, species concentration, and current generation. In order to investigate the distributions of various parameters in the land-channel direction, we developed a small-scale segmented cell with about 350-micron resolution, and successfully measured the current and high-frequency resistance distribution in the land-channel direction for two different flow fields.

Biographical Sketch: Dr. Kazuya Tajiri is an associate professor of Department of Mechanical Engineering-Engineering Mechanics at Michigan Technological University. He has obtained his Bachelor degree in Aeronautics and Astronautics from University of Tokyo, Master degree in Aerospace Engineering from Georgia Institute of Technology, and Ph. D in Mechanical Engineering from The Pennsylvania State University. After obtaining a Ph.D degree, he worked at Argonne National Laboratory as a postdoctoral researcher, and then in 2010 he joined Michigan Technological University as an assistant professor. He also has work experience at Nissan Research Center in Yokosuka, Japan. In 2013, he was selected as one of the finalists for the Distinguished Teaching Award at Michigan Technological University.

Abstract: The 9-month journey home from Mars could begin with a 9 ns laser pulse.  Ignition in rocket combustors is typically accomplished using a spark plug, a pyrotechnic charge, an injection of hypergolic fluid, or a hot gas torch. These methods involve significant mechanical complexity, increase the inert mass with ancillary subsystems, limit the potential for engine re-ignitions throughout a mission, and require additional (often toxic) propellants. Non-resonant breakdown ignition is an alternative method in which the ignition energy is provided through a focused pulse of laser light. If the local flow conditions in the vicinity of the spark are suitable, a flame will develop and stabilize within the combustor. Laser-induced spark ignition holds significant promise for rocket combustion systems because the point of energy deposition can be precisely placed at an optimum location that minimizes the ignition energy requirement.  This talk will focus on an experimental characterization ignition probability in a gaseous oxygen and gaseous methane combustor. The oxygen-centered shear co-axial injector generated a widely varying mixture field and velocity field to create significant variability in both the ignition process and outcome.  Results from time-resolved imaging diagnostics will be discussed to explain the mechanisms that manifest the final ignition probability.

Biographical Sketch: Dr. Carson Slabaugh is the Paula Feuer Associate Professor in the School of Aeronautics and Astronautics at Purdue University.  Since joining Purdue in 2015, he has developed an education and research program focused on propulsion.  Dr. Slabaugh’s laboratory is housed within the Purdue Zucrow Laboratory complex, with high pressure, high flow-rate system capabilities to enable experimental replication of the flow and flame conditions (pressure, turbulence level, thermal power density) found in the most advanced propulsion and combustion systems.  Ongoing research projects cover a wide range of topics: from the fundamental exploration of detonations and turbulent flames to the development of advanced combustion technologies for liquid rocket engines and rotating detonation engines. His group also maintains a continuous effort in the advancement of high-bandwidth (typically, laser-based) measurement techniques to non-intrusively probe the physics of these complex, reacting flows.  Support for these research projects has been provided by AFOSR, AFRL, DARPA, DOE, NASA, ONR, and numerous industrial partners.  Prof. Slabaugh has published extensively in the field and is involved with multiple national efforts to transition advanced concepts into aerospace propulsion technologies.

Abstract: Chalcogenide phase change materials (PCMs) have promising properties for photonic applications thanks to their nonvolatile and large refractive index modulation [1]. The last decade has seen a growing interest in such a combination of properties for a variety of nonvolatile programmable devices, such as metasurfaces, tunable filters, phase/amplitude modulators, color pixels, thermal camouflage, photonic memories/computing, plasmonics, etc.—giving rise to the so-called Phase-change Photonics field.[1] PCM-based devices rely on the precise switching between the amorphous and the crystalline states, which can be achieved through optical or electrical pulses via optical absorption and Joule heating, respectively. Optical pulse switching is the fastest and most precise method; however, it lacks scalability given the difficulty of on-chip pulse routing when considering many PCM cells. It is also limited to absorptive PCMs, such as Ge2Sb2Te5. As a scalable alternative, on-chip microheaters using multiple material platforms have been proposed, e.g. doped-silicon, graphene, ITO, metals, etc. Doped-silicon microheaters are particularly interesting since they are CMOS compatible and can be fabricated onto silicon-on-insulator (SOI) wafers—the same platform used for silicon photonic integrated circuits. However, this electro-thermal switching also has shortcomings. It lacks stable multi-level response due to the stochastic nature of both amorphization and crystallization processes in the typical bow-tie-like devices where the microheater heats the entire cell to an almost flat temperature [2,3]. Because of this, the focus is shifting towards the microheater’s geometry in addition to the choice of conductive material and its integration. One common goal is to control the hotspot size within the PCM cell to deterministically switch specific areas (i.e., spatially resolved amorphous domains in a crystalline cell) and, thus, achieve controllable and reproducible optical modulation [4,5]. In this talk, I will review the fundamentals of PCM for photonics and the proposed electro-thermal mechanisms. I will then focus on our current efforts to re-engineer doped-silicon microheaters for optimum performance.

[1] M. Wuttig, et, al. “Phase-change materials for non-volatile photonic applications,” Nat. Photon.11(8), 465–476 (2017).

[2] J. Feldmann, et, al. “Calculating with light using a chip-scale all-optical abacus,” Nat Commun 8(1), 1256 (2017)

[3] T. Tuma, et, al. “Stochastic phase-change neurons,” Nat. Nanotechnol.11(8), 693–699 (2016).

[4] C. Ríos, et, al “Ultra-compact nonvolatile phase shifter based on electrically reprogrammable transparent phase change materials,” PhotoniX 3(1), 26 (2022).

[5] X.  Li, et, al, “Fast and reliable storage using a 5 bit, nonvolatile photonic memory cell,” Optica 6, 1-6 (2019)

[6] Y. Zhang, et, al, “Myths and truths about optical phase change materials: A perspective.” Appl. Phys. Lett. 118 (21): 210501.

Biographical Sketch: Carlos A. Ríos Ocampo is an Assistant Professor at the University of Maryland, College Park, where he has led the Photonic Materials & Devices groups since 2021. Before joining UMD, Carlos was a Postdoctoral Associate at MIT, received a DPhil (PhD) degree in 2017 from the University of Oxford (UK), an MSc degree in Optics and Photonics in 2013 from the KIT (Germany), and a BSc in Physics in 2010 from the University of Antioquia (Colombia). Carlos’s scientific interests focus on studying and developing new on-chip technologies driven by the synergy between nanomaterials and photonics.