SAFL building

Every two weeks during the academic year, SAFL hosts prominent figures in environmental science and fluid mechanics. They come from all over the US and the world to share their insight and inspire us to tackle important questions in the field. These seminars are free and open to the public. Join us to learn about the latest research advancements and network with contacts in the field.

SAFL seminars are held on Tuesdays, from 3:00 to 4:15 p.m., either online, in the SAFL Auditorium or as hybrid events. 

Spring 2023 Seminar Series

February 14th Jacqueline Reber, Iowa State University

February 21st – Blair Johnson, UT Austin

February 28th – Hamid Moradkhani, University of Alabama

March 14th – Grae Worster, University of Cambridge

March 21st – Guiju Song, General Electric

March 28th – Michael Lamb, California Institute of Technology

April 4th Vicente Diaz, University of Minnesota

April 11th – Kenneth Belitz, United States Geological Survey

April 18th Ruben Juanes, Massachusetts Institute of Technology 

April 25th – Keith Moored, Lehigh University

May 2nd Peter Sullivan, National Center for Atmospheric Research

We will record seminars and post them here when given permission by the speaker. To see if a recording is available, scroll down this page to "Past Seminars."

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Upcoming Seminars

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Past Seminars

Bacterial biofilm as a model for studying mechanical instabilities - Jing Yan, Yale University

Jing Yan, Assistant Professor of Molecular, Cellular and Developmental Biology and a member of the Quantitative Biology Institute (Qbio) at Yale University.

embedded biofilm

AbstractBiofilms, surface‐attached communities of bacterial cells, are a concern in health and in industrial operations because of persistent infections, clogging of flows, and surface fouling. On the other hand, biofilms also display many interesting mechanical instabilities and behave as unique active materials. In this talk, I will discuss our recent progress in using Vibrio cholerae as a model to reveal the physical principles behind biofilm formation, in particular in confined environment, both at the single cell level and at the continuum level. In this process, we discovered a deep connection between biofilm growth and phenomena in soft materials including cavitation, delamination, and stress birefringence. 

Jing Yan

About: Jing Yan is currently an Assistant Professor of Molecular, Cellular and Developmental Biology and a member of the Quantitative Biology Institute (Qbio) at Yale. Originally from Shanghai, China, he obtained his B.S. degree from the College of Chemistry and Molecular Engineering at Peking University in China, with extensive undergraduate research experience in organic synthesis. In 2009, he switched to the field of soft matter physics and pursued Ph.D. degree in the Department of Materials Science and Engineering at the University of Illinois at Urbana-Champaign. Working with Steve Granick, he developed novel reconfigurable, active colloidal materials during his Ph.D.

In 2014, he stumbled into microbiology at Princeton as a joint postdoctoral researcher in the department of Molecular Biology and Mechanical and Aerospace Engineering. Working with Bonnie Bassler, Howard Stone, and Ned Wingreen, he studied bacterial biofilms with an interdisciplinary approach. With new imaging techniques, he discovered the spontaneous cellular ordering inside V. cholerae biofilms that leads to the formation of tenacious biofilm clusters. His study on the biofilm material properties leads to innovative methods to remove harmful biofilms. He received the Career Award at the Scientific Interface from Burroughs Wellcome Fund in 2016.

Jing received the Career Award at the Scientific Interface from Burroughs Wellcome Fund in 2016 and NIH Director’s New Innovator Award in 2021.  

Lorenz G. Straub Award Ceremony with Distinguished Lecture by Prof. Marccus Hendricks

Join us on Tuesday, November 29th at 3pm for a celebration of the 2021 Lorenz G. Straub Award recipient Dr. Andrew Feldman, with a distinguished lecture by Prof. Marccus Hendricks.

Marccus Hendricks, Associate Professor of Urban Studies and Planning and the Director of the Stormwater Infrastructure Resilience and Justice (SIRJ) Lab at the University of Maryland

Distinguished lectureSocio-Physical Infrastructure and Environmental Risks: People, Pipelines, and Pathways

AbstractThe impact of hazard exposures such as stormwater runoff is rarely evenly felt across a community. Neighborhoods of color, particularly of low-wealth, will often face worse stormwater problems especially in the era of climate change; with more frequent and intense stormwater runoff. Dr. Marccus Hendricks will discuss the equity and environmental justice issues related to stormwater infrastructure planning that result in vulnerable systems, leading to everyday challenges in stormwater, urban flooding, and other environmental risks. Specifically, he will examine conceptual frameworks and contextualize what it means for physical systems to operate in a social world. He will describe several ongoing studies where his lab investigates a number of risks at the nexus of stormwater, infrastructure, resilience, and environmental justice. Furthermore, he will discuss pathways forward that integrate justice and participation into the inspection and improvement of community spaces, particularly in marginalized areas.


About the speakerDr. Marccus Hendricks is a recently tenured Associate Professor of Urban Studies and Planning and the Director of the Stormwater Infrastructure Resilience and Justice (SIRJ) Lab at the University of Maryland. His other appointments at the university include the Department of Civil and Environmental Engineering and the Maryland Institute for Applied Environmental Health. He holds a Ph.D. in Urban and Regional Science and a Master of Public Health, both from Texas A&M University. To date, he has primarily worked to understand how social processes and development patterns create hazardous human-built environments, vulnerable infrastructure, and the related risks in urban stormwater management and flooding. Other work has focused on technological disasters, namely fertilizer explosions, and cascading events such as wet- weather events that overwhelm sanitary sewers and cause overflows, household backups, and contamination. His work emphasizes participation and action that uses methods including photography, visual inspection, and environmental sampling.

Hendricks’ research has been published in several journals including the Journal of the American Planning Association, Journal of Planning Education and Research, American Journal of Public Health, Environmental Justice, Journal of Infrastructure Systems, Risk Analysis, Landscape Journal, and Sustainable Cities and Society. In the popular media realm, his work has been covered by or quoted in the Associated Press, CNN, NPR, USA Today, Scientific American, Huffington Post, Baltimore Sun, and, to name a few.

Hendricks received two early-career awards from the National Academies of Science Gulf Research Program and The JPB Environmental Health Fellows Program at Harvard T. H. Chan School of Public Health. More recently, he was named as a 2021 “Fixer” by the media company Grist for their annual Grist 50 Fixer list and has been appointed to Springer Nature’s US Research Advisory Council, the U.S. EPA’s Science

Advisory Board, and by the Biden Administration as an author on the human social systems chapter of the U.S. Fifth National Climate Assessment.

2021 Lorenz G. Straub Recipient Dr. Andrew FeldmanNASA Postdoctoral Program Fellow at the NASA Goddard Space Flight Center

Doctoral thesisSoil-Plant-Atmosphere Coupling during Interstorm Periods

AbstractThe future trajectory of net terrestrial carbon uptake and agricultural yields are dependent on how vegetation responds to climate forcings. However, characterizing vegetation responses to water stress and other environmental drivers is challenging because these forcing factors are inter-related, especially on seasonal timescales. Here, recently available global mapping measurements from microwave satellite sensors are used to characterize water exchange in the soil-plant-atmosphere continuum. These satellites enable evaluation of time evolution of landscape-scale plant water content during interstorm periods, providing insights into underlying mechanisms and allowing disentangling of their drivers. My thesis asks: what are the fundamental landscape-scale plant responses to rainfall events and interstorm drying? With a focus on soil-plant hydraulics in this presentation, I’ll more specifically ask: at what timescale do plants take up water after a rain event and why?

Following soil moisture pulses in wetter global locations, rapid soil-plant water coupling occurs as expected under pre-dawn soil-plant equilibrium. By contrast, in global drylands, plant water content commonly increases over multiple days after pulses. Longer dryland plant water content increases (> 3 days) are attributed to rapid growth, providing evidence for a long-standing ecological hypothesis. In contrast, shorter (1-3 day) plant water increases under dry conditions are due to slow plant rehydration, ascribed here to high soil-plant resistances using a plant hydraulic model. These results together suggest that intermittent pulses of water availability have the strongest influence on dryland vegetation. However, responses extend across climate gradients implicating widespread sensitivity to rainfall timing.


About the recipientAndrew Feldman is a NASA Postdoctoral Program Fellow at the NASA Goddard Space Flight Center located in Greenbelt, MD. He works primarily with Ben Poulter on carbon cycle science in the Biospheric Sciences Laboratory. He is a hydrologist who studies the coupling of the terrestrial water, carbon, and energy cycles mainly using satellite remote sensing platforms across optical, thermal, and microwave frequencies. Andrew is also a new member of the NASA ECOSTRESS Science Team. Prior to joining NASA, Andrew was a graduate research assistant at Massachusetts Institute of Technology, Cambridge, MA, where he received S.M. and Ph.D. degrees in hydrology in the department of civil and environmental engineering in 2018 and 2021, respectively. At MIT, he worked with Prof. Dara Entekhabi. He also completed his bachelor’s and master’s degrees in civil engineering from Drexel University in Philadelphia, PA in 2016.

The Ghost Valley - Sara Holger, Lead Interpretive Naturalist at Whitewater State Park

Please join us on Monday, November 14th for two events featuring Sara Holger: a panel discussion at 12:30pm and a Beyond the Lab Seminar at 3pm.

Sara Holger, Lead Interpretive Naturalist at Whitewater State Park in Minnesota

Panel discussion with Sara Holger, Prof. Andy Wickert & Jimmy Wood 

Monday, November 14th

In-person at St. Anthony Falls Laboratory at 12:30pm

Sara will be in conversation with SAFL collaborators Prof. Andy Wickert and Jimmy Wood, with the discussion moderated by Shanti Penprase. Panelists will discuss the benefits of collaboration between the University and state parks, balancing priorities amongst partners, funding interdisciplinary work and more. Panelists will also engage with audience members, so please bring your questions! Snacks will be provided.

Beyond the Lab Seminar - The Ghost Valley

Monday, November 14th

In-person and online at 3pm

Abstract: The Whitewater River Valley lies within portions of Olmsted, Wabasha and Winona counties in the Driftless area of southeast Minnesota. Once home to five towns, visitors to the valley today find several ghost towns and the footprints of nearly 100 farms that have vanished. This presentation will explore the fascinating history of the Whitewater River watershed and how human land use, erosion and destruction catastrophically altered human lives and the natural resources of the valley.

Sara Holger

About: Sara has been an environmental educator since 1994. She graduated from the University of Minnesota – Twin Cities campus in 1998 with an undergraduate degree in Natural Resources and Environmental Studies. Over the course of her career, she’s worked for various agencies and organizations including the US Forest Service, the Bell Museum of Natural History, the Minnesota Department of Natural Resources – Division of Fisheries, Eagle Bluff Environmental Learning Center, Olmsted County Parks, and Minnesota State Parks and Trails. Sara is the Lead Interpretive Naturalist at Whitewater State Park. She is also the Founder of a non-profit organization called Project Get Outdoors, working to connect low-income youth and Children of Color to the natural world. Sara farmed for 11 years in the Whitewater River watershed and is grateful to have learned through experience about the farming community and the incredible work our farmers do to feed the world. In her spare time she enjoys fishing, kayaking and exploring public lands in southeast Minnesota with her family.

Beyond the Lab Seminars

We love learning from prominent figures in environmental science and fluid mechanics through the SAFL Seminar Series, just as we recognize the value in examining any issue, idea, or area of study from a multitude of perspectives. Beyond the Lab seminars allow us to do just this: by bringing in experts from other fields and the community, we enrich our understanding of environmental science and fluid mechanics while situating research and other concepts in a holistic context. 

Do you have an idea for a Beyond the Lab Seminar? Email Clare at

Carbonate mineral reactions during geological carbon sequestration, and implications for induced seismicity - Charles Werth, UT-Austin

Charles Werth, Professor & Bettie Margaret Smith Chair of Environmental Health Engineering in the Department of Civil, Architecture, and Environmental Engineering at the University of Texas at Austin.

Abstract: Geologic carbon sequestration in deep saline aquifers results in a low pH brine plume that pushes into subsurface storage reservoirs and can access pre-existing or induced (micro)fractures and possibly induce shear slip.  To investigate this phenomenon, an artificial fracture was created in a Bandera Gray sandstone sample, and it was held under shear stress in a custom flow cell housed within an industrial CT scanner. Acidic (pH 4) or reservoir-simulated (pH 8.3) brine was pumped through the artificial fracture for seven days. CT imaging shows that acidic brine resulted in greater shear slip than reservoir-simulated brine, and fracture surfaces exposed to acidic brine had rougher surfaces and lower fracture toughness. SEM images of fracture surfaces indicate a loss by area of carbonate cementing crystals after exposure to the acidic brine, as well as a corresponding porosity increase. These results motivated more fundamental studies on carbonate mineral dissolution using freshly cleaved calcite.  The effects of solution pH, carbonic acid, and the presence of an anionic surfactant on calcite dissolution kinetics and etch pit morphology were probed in a high pressure and temperature reactor, and complemented with density functional theory calculations.  Results indicate that carbonic acid promotes much faster dissolution than protons or water, and that the anionic surfactant inhibits dissolution by competing with carbonic acid for calcium edge sites on the calcite surface.  Hence, addition of anionic surfactants to injected CO2 may inhibit calcite dissolution and slip along existing fractures. 

Charles Werth

AboutDr. Werth is a Professor and the Bettie Margaret Smith Chair in Environmental Health Engineering at the University of Texas at Austin. His research and teaching focus on the reactive transport of water pollutants in porous media, with applications in (electro)catalytic water treatment, groundwater remediation, and geological carbon sequestration. He is editor of Journal of Contaminant Hydrology, and previously served on the USEPA Science Advisory Board.  He received his BS degree in mechanical engineering from Texas A&M University, and MS and PhD degrees in environmental engineering from Stanford University.

Edward Silberman Award Ceremony & Distinguished Lecture by Prof. Anna Trugman

Presentation of the 2022 Edward Silberman Fellowship to Reyhaneh Rahimi

Distinguished Lecture: Plant functional traits in terrestrial hydrological and carbon cycles

Distinguished SpeakerAnna Trugman, Assistant Professor in the Department of Geography at the University of California, Santa Barbara

AbstractClimate change has the potential to massively disrupt terrestrial ecosystem productivity, impacting biodiversity, and driving Earth’s forests to release carbon into the atmosphere, which would further exacerbate climate change and modify the hydrological cycle. Plant functional traits, such as those that determine tree drought vulnerability, and the diversity in traits within a forest, modulate surface water, carbon, and energy fluxes. Yet, we do not know how species composition and their accompanying traits will change with climate change. In this talk, I leverage plant physiological observations, large observational databases, and trait-based ecosystem models to understanding the extent to which plant trait diversity can impact ecosystem resilience to drought events, and the subsequent effects on ecosystem carbon and water fluxes. Using a trait-based vegetation model and observed maps of hydraulic traits, I generated maps of plant water status and hydraulic stress and examine the extent to which trait acclimation and turnover can ameliorate future climate stress. Importantly observed trait velocities (changes in forest community trait compositions over time) are not keeping pace with the required compositional shifts to mitigate increases in hydraulic stress.

Anna Trugman

AboutAnna Trugman is an Assistant Professor in the Department of Geography at the University of California, Santa Barbara. Her research is focused on the biogeochemical and hydrological consequences of forest physiological and ecological responses to climate change through combined observational and modeling approaches. Anna is a recipient of the New Phytologist Tansley Medal for outstanding research in plant sciences, the Ecological Society of America Early Career Award, and the American Geophysical Union Global Environmental Change Early Career Award.

Award recipient: Reyhaneh Rahimi, Department of Civil, Environmental and Geo- Engineering

Abstract: Precipitation nowcasting, the high-resolution forecasting of precipitation up to 6 hours ahead, supports the real-world socioeconomic needs of many sectors reliant on weather-dependent decision-making. Today’s weather predictions are driven by powerful numerical weather prediction (NWP) systems. By solving physical equations, NWPs provide essential planet-scale predictions several days ahead. However, they struggle to generate high-resolution predictions for short lead times. On the other hand, current remotely sensed precipitation products have a few hours of latency, associated with the acquisition and processing of satellite data. In my research I want to reduce this latency and improve their applicability, value, and impact by applying a robust nowcasting system to these products. However, the development of such a system is complicated by the chaotic nature of the atmosphere, and the consequent rapid changes that can occur in the structures of precipitation systems. Using Recurrent and Convolutional deep neural network structures to I tried to address the challenge of precipitation nowcasting and develop a model that can provide precipitation estimation for up to four hours ahead. The results demonstrate that the performance of the deep learning-based forecasting model can outperform the numerical weather prediction models.

Reyhaneh Rahimi

About the recipient: Reyhaneh Rahimi is a Ph.D. candidate in Civil Engineering (Water Resources Management) at the St. Anthony Falls Laboratory studying under Prof. Ardeshir Ebtehaj. Reyhaneh holds a Bachelor of Science and Master of Science in Civil Engineering from the University of Tehran. Her research interests include remote sensing of land-atmosphere interactions, statistical hydrology and analysis of uncertainties, satellite hydrology and precipitation retrievals, and hydrological modeling and optimization.


Microwave remote sensing of plant water stress - Alexandra Konings, Stanford University

Alexandra Konings, Assistant Professor in the Department of Earth System Science at Stanford University

Abstract: Understanding how vegetation responds to changes in hydrological conditions is a fundamental prerequisite for characterizing the response of ecosystems to a changing hydroclimate. However, doing so is challenging because of the large diversity of relevant vegetation traits (including root, xylem, and stomatal properties) within species, within ecosystems, and across the globe. In this talk, I will describe how microwave remote sensing of vegetation – which naturally integrates over these sources of variability and provides data across the globe - may be a useful tool for better understanding plant water stress response. In this talk, I will discuss active and passive microwave observations and their sensitivity to vegetation water content. I will further discuss evidence that ecosystem-scale variations in vegetation water content are not just sensitive to biomass - as commonly used - but also carry the signature of variations in leaf water potential, the physiological variable that most directly influences plant water stress response. I will discuss how this signature can be used for several applications, including determining ecosystem-scale plant hydraulic traits (including isohydricity, stomatal closure, P50, and xylem closure) and their link to spatial variability in photosynthesis responses to water stress, estimating drought-driven tree mortality rates, and characterizing wildfire risk.

Alex Konings

About: Alexandra 'Alex' Konings is an assistant professor in the department of Earth System Science at Stanford University. She also has a courtesy appointment in the Stanford Department of Geophysics and is a center fellow, by courtesy, of the Stanford Woods Institute of the Environment. Her research is focused on interactions between the global carbon and water cycles, especially as related to plant hydraulics and to the effects of small-scale trait variability on regional-scale ecosystem behavior. She received the NASA New (Early Career) Investigator Award in 2018, the NSF CAREER in 2020, and the AGU Global Environmental Change Early Career Award in 2021.

Roger E.A. Arndt Fellowship Award Ceremony & Distinguished Lecture by George Karniadakis

Presentation of the 2022 Roger E.A. Arndt Fellowship

Distinguished Lecture: Physics-Informed Deep Learning: Blending data and physics for fast predictions

Distinguished SpeakerGeorge Em Karniadakis, the Charles Pitts Robinson and John Palmer Barstow Professor of Applied Mathematics and Engineering at Brown University, research scientist at Massachusetts Institute of Technology, and director of the Physics-Informed Learning Machines for Multiscale and Multiphysics Problems (PhILMs) at the Pacific Northwest National Laboratory

Abstract: In this lecture, we will review physics-informed neural networks and summarize available extensions for applications in computational mechanics and beyond. We will also introduce new NNs that learn functionals and nonlinear operators from functions and corresponding responses for system identification. The universal approximation theorem of operators is suggestive of the potential of NNs in learning from scattered data any continuous operator or complex system. We first generalize the theorem to deep neural networks, and subsequently we apply it to design a new composite NN with small generalization error, the deep operator network (DeepONet), consisting of a NN for encoding the discrete input function space (branch net) and another NN for encoding the domain of the output functions (trunk net). We demonstrate that DeepONet can learn various explicit operators, e.g., integrals, Laplace transforms and fractional Laplacians, as well as implicit operators that represent deterministic and stochastic differential equations. More generally, DeepOnet can learn multiscale operators spanning across many scales and trained by diverse sources of data simultaneously.

George Karniadakis

About the speaker: George Karniadakis is from Crete. He is a member of the National Academy of Engineering and a Vannvar Bush Faculty Fellow. He received his S.M. and Ph.D. from Massachusetts Institute of Technology (1984/87). He was appointed Lecturer in the Department of Mechanical Engineering at MIT and subsequently he joined the Center for Turbulence Research at Stanford/Nasa Ames. He joined Princeton University as Assistant Professor in the Department of Mechanical and Aerospace Engineering and as Associate Faculty in the Program of Applied and Computational Mathematics. He was a Visiting Professor at Caltech in 1993 in the Aeronautics Department and joined Brown University as Associate Professor of Applied Mathematics in the Center for Fluid Mechanics in 1994. After becoming a full professor in 1996, he continued to be a Visiting Professor and Senior Lecturer of Ocean/Mechanical Engineering at MIT. He is an AAAS Fellow (2018-), Fellow of the Society for Industrial and Applied Mathematics (SIAM, 2010-), Fellow of the American Physical Society (APS, 2004-), Fellow of the American Society of Mechanical Engineers (ASME, 2003-) and Associate Fellow of the American Institute of Aeronautics and Astronautics (AIAA, 2006-). He received the SIAM/ACM Prize on Computational Science & Engineering (2021), the Alexander von Humboldt award in 2017, the SIAM Ralf E Kleinman award (2015), the J. Tinsley Oden Medal (2013), and the CFD award (2007) by the US Association in Computational Mechanics. His h-index is 123 and he has been cited over 70,000 times.

Award Recipient: Vinicius Taguchi, Department of Civil, Environmental and Geo- Engineering

Abstract: Recent research has demonstrated that urban stormwater ponds can experience internal phosphorus loading. As primary stormwater runoff treatment practices, the resulting poor water quality can be problematic for the lakes and other sensitive downstream ecosystems that the stormwater ponds are intended to protect. Many remediation strategies are available to pond managers combatting internal phosphorus loading, but effectiveness and cost-effectiveness are difficult to ascertain given the wide variability of stormwater ponds and the small amount of pond-specific management research when compared to lakes and reservoirs. We modeled four stormwater ponds in CE-QUAL-W2 and simulated six remediation scenarios: chemical treatment of sediments with alum, outlet reorientation, mechanical mixing, reduced wind sheltering, watershed modifications to reduce volume and reduce concentration, and bathymetry modifications. We evaluated the effectiveness of each scenario both qualitatively and quantitatively, and we estimated the cost-effectiveness of each based on practitioner experience. Remediation recommendations for each stormwater pond will vary depending on its unique stresses, context, and performance goals, so we provide a comparison tool that can be used to examine options from multiple perspectives.

Vini Taguchi

About the recipient: Vini Taguchi is a Ph.D. candidate in Civil Engineering at the St. Anthony Falls Laboratory studying under Dr. John Gulliver and Dr. Jacques Finlay. His research is focused on understanding and controlling internal phosphorus loading in urban stormwater ponds. Vini is also working part-time as a Stormwater Extension Associate at North Carolina State University under Dr. William F. Hunt III, where his work is more broadly focused on urban green infrastructure projects. In his free time, Vini serves as the current president of the Twin Cities chapter of the Japanese American Citizens League, a civil rights organization committed to fighting for social justice for all those who are victimized by injustice and bigotry.

Coupling between river flow, suspended sediment, and morphodynamics - Aaron Packman, Northwestern University

Aaron Packman, Professor of Civil and Environmental Engineering & Director of the Northwestern Center for Water Research at Northwestern University

AbstractThere is increasing concern about the effects of land development, flow regulation, and climate change on the stability of rivers, deltas, and aquatic ecosystems.  Both local and long-distance effects are regulated by the propagation of eroded soils and other fine particles through river systems. Such small particles are generally assumed to be transported by rivers in a passive way, without interacting significantly with the riverbed or influencing river morphodynamics. I will present results from laboratory and field experiments to show that suspended fine particles propagate into streambeds, are remobilized by bed sediment transport, and substantially modify key fluvial processes including hyporheic exchange and river morphodynamics. I will also present a mathematical model that captures the essential dynamics of fluid, solute, and particle propagation through rivers, and discuss prospects for prediction of fluvial system dynamics.

Aaron Packman

AboutAaron Packman is a Professor of Civil and Environmental Engineering and the Director of the Center for Water Research at Northwestern University. He holds a joint appointment at Argonne National Laboratory as a Senior Fellow in the Northwestern-Argonne Institute of Science and Engineering. Dr. Packman is the U.S. Director of the U.S.-Israel Collaborative Water-Energy Research Center (CoWERC), managed by the Binational Industrial Research and Development Foundation (BIRD) and funded by the U.S. Department of Energy, Israel’s Ministry of Energy, and the Israel Innovation Authority. Dr. Packman is an internationally recognized expert in water resources, surface-groundwater interactions, and biological and biogeochemical processes in aquatic systems. Dr. Packman’s research team is working to solve a variety of problems, including nutrient pollution, urban flooding, ecosystem degradation & restoration, and waterborne disease transmission. He currently serves on the Leadership Team of the Smart Great Lakes Initiative, as well as its Science, Technology, and Innovation team. Packman has received numerous awards and honors, including Fellow of the American Geophysical Union, a Fulbright Distinguished Chair in Hydrology and Hydraulic Engineering, the Huber Research Prize from the American Society of Civil Engineers, and Career Awards from the National Science Foundation and National Institutes of Health. He received a B.S. in Mechanical Engineering from Washington University in St. Louis, and an M.S. and Ph.D. in Environmental Engineering and Science from the California Institute of Technology.

Lorenz G. Straub Award Ceremony with Distinguished Lecture by Provost Fotis Sotiropoulos

Join us on Tuesday, April 19th at 3pm for a celebration of the 2020 Lorenz G. Straub Award recipient Dr. Samantha Hartzell, with a distinguished lecture by Provost Fotis Sotiropoulos.

Fotis Sotiropoulos, Provost and Senior Vice President for Academic Affairs at Virginia Commonwealth University

Title: Optimizing Wind Energy Systems via Numerical Simulation: From Novel Wake Physics and Data-Driven Models to Control Co-Design of Large Wind Farms

Fotis 1

AbstractWind energy is rapidly becoming a disruptive renewable energy technology with the potential to dominate the world’s electric energy production portfolio. Realizing this goal, however, necessitates broadening the focus of research from the individual turbine to integrated, interconnected multi-turbine wind farms.  Recent high-fidelity large-eddy simulations (LES) coupled with laboratory and field scale experiments have revolutionized our understanding of the rich dynamics of wind turbine wakes, elucidated the impact of near-wake phenomena to far wake meandering, and yielded striking insights into the effects of turbine-induced coherent structures to wind-farm scale dynamics.  In this talk I will discuss the challenges and opportunities for high-fidelity modeling as a powerful tool for enabling wind-farm optimization.  I will review recent advances in developing a high-fidelity, fluid-structure interaction computational framework for carrying out large-eddy simulation of atmospheric turbulence past land-based and offshore wind-farms in arbitrarily complex terrains incorporating wind turbine blade aerolasticity and turbine controllers. I will present recent results that: 1) illustrate the ability of high-fidelity simulations to serve as a powerful tool of scientific discovery by augmenting knowledge derived from laboratory and field scale experiments to uncover novel complex flow physics; 2) demonstrate the predictive capability of high-fidelity simulations when applied to utility-scale wind farms; and 3) show for the first time that coupling ambient turbulent flow with advanced turbine control strategies (individual blade pitch control) can reduce blade bending loads pointing to the potential of control co-design as a powerful approach for reducing the levelized cost of energy of large wind farms.  Finally, I will demonstrate the efficacy of developing highly efficient LES-data-trained reduced order models using machine learning and convolutional neural networks, which paves the way for a powerful computational framework for control co-design and optimization of large wind farms.

Fotis again

About the speaker: Fotis Sotiropoulos serves as the Provost and Senior Vice President for Academic Affairs at Virginia Commonwealth University.  Prior to that he was Dean of the College of Engineering and Applied Sciences and State University of New York (SUNY) Distinguished Professor of Civil Engineering at Stony Brook University (2015-2021). Before joining Stony Brook University, he was the James L. Record Professor of Civil Engineering; Director of the St. Anthony Falls Laboratory; and Director of the EOLOS wind energy research consortium at the University of Minnesota, Twin Cities (2006-2015). Prior to that, he was on the faculty of the School of Civil and Environmental Engineering at the Georgia Institute of Technology, with a joint appointment in the G. W. Woodruff School of Mechanical Engineering (1995-2005).  His research focuses on simulation-based engineering science for tackling complex, societally relevant fluid mechanics problems in renewable energy, environmental and human health applications. He has authored over 200 peer reviewed journal papers and book chapters and his research results have been featured on the cover of several prestigious journals. He is the 2019 recipient of the American Geophysical Union (AGU) Borland Lecture award, the 2017 recipient of the Hunter Rouse Hydraulic Engineering Award from the American Society of Civil Engineers (ASCE), Fellow of the American Physical Society (APS) and the American Society of Mechanical Engineers (ASME), and a recipient of a Career Award from the National Science Foundation.  He has twice won the APS Division of Fluid Dynamics Gallery of Fluid Motion (2009, 2011), is a 2014 distinguished lecturer of the Mortimer and Raymond Sackler Institute of Advanced Studies at Tel Aviv University and has served on the editorial boards of several journals.

2020 Lorenz G. Straub Recipient Samantha Hartzell, Assistant Professor in the Department of Civil and Environmental Engineering at Portland State University

Doctoral thesisThe role of CAM photosynthesis in the soil-plant-atmosphere continuum

AbstractIn arid and semiarid climates, water availability often limits the potential for food security, energy production, and carbon storage. One avenue for water conservation is through Crassulacean acid metabolism (CAM) photosynthesis, a pathway which naturally occurs in up to 50% of the total plant biomass in dryland ecosystems. Vegetation with this pathway utilizes an inverted circadian rhythm to achieve a water use efficiency six to ten times higher than that of typical C3 plants. Here I will introduce advances in the modeling of CAM photosynthesis and water use, including an analysis of its nonlinear dynamics in response to environmental forcing and the emergence of chaotic behavior (as observed in nature). This treatment of the CAM circadian rhythm enables the development of a unified model of all three photosynthetic pathways (C3, C4, and CAM) coupled hydraulically to soil and atmospheric conditions. Results predict CAM water use at the plot scale for the first time and allow carbon and water exchanges to be compared consistently among the three photosynthetic pathways.

Samantha Hartzell

About the speakerSamantha Hartzell is an assistant professor at Portland State University. Her research interests focus on both urban and dryland ecohydrology, and she has recently received funding from the National Science Foundation to study impacts of vegetation type on green roof runoff reduction. She was a National Science Foundation Graduate Research Fellow at Duke University, where she received her M.S. in 2017, and Princeton University, where she received her Ph.D. in 2020. Her doctoral thesis, supervised by Prof. Amilare Porporato, is entitled “The role of CAM photosynthesis in the soil-plant-atmosphere continuum.” Dr. Hartzell’s work on the unified modeling of C3, C4, and CAM photosynthesis received the Robert H. Socolow Carbon Mitigation Initiative best paper award for Princeton University graduate students in 2020. She is a member of the National Association of Geoscience teachers, the American Geophysical Union, and the Chi Epsilon Civil Engineering Honor Society.

History of the Fellowship: The Lorenz G. Straub Award is awarded annually for the most meritorious thesis in hydraulic engineering, ecohydraulics, or a related field. Applicants are internationally entered and nominations may be made by any recognized civil and environmental engineering program in the world. The establishment of the Lorenz G. Straub Award was announced at the dedication of the Lorenz G. Straub Memorial Library within St. Anthony Falls Laboratory by Edward Silberman. When the Straub Award was established, it was recognized that it was unique in its nature. In the years of its existence, it has come to be widely recognized professionally and has accrued much honor to its recipients.

Experimental investigations of the fluid mechanics involved in wind turbines at very high Reynolds number - Marcus Hultmark, Princeton

Marcus Hultmark, Associate Professor in the Department of Mechanical & Aerospace Engineering at Princeton University

Abstract: Wind turbines and wind farms present unique challenges—fluid mechanically—as they combine extremely high Reynolds numbers with additional time scales imposed by the rotation, and three-dimensional effects. This implies that resolved numerical solutions are too computationally expensive and investigations in conventional wind tunnels are impossible due to the flow speeds and rotational rates needed in order to satisfy the dynamic similarity requirements. At Princeton, we achieve the conditions a large wind turbine experiences, experimentally, by compressing the air around a model-scale turbine up to 238 bar. This yields conditions similar to those experienced by a field-sized turbine using a model that is only 20 cm in diameter. High pressure enables tests at high Reynolds numbers but at low velocities, which implies that realistic non-dimensional frequencies can be tested even with such a small model. This unique feature is used both to study rotating wind turbines and their wakes, as well as the unsteady aerodynamics that are involved in these machines.

Marcus Hultmark

AboutMarcus Hultmark is an associate professor in the Department of Mechanical and Aerospace Engineering at Princeton University, and he is the director of the Princeton Gas Dynamics Lab. His research interests include a variety of problems related to fluid mechanics, with focus on problems involving turbulence, such as heat and mass transfer as well as drag reduction and wind energy. Theoretical work is combined with experimental studies, and an important part of his research program is the development and evaluation of new sensing techniques to investigate these phenomena with high accuracy, including velocity, temperature and humidity sensors. He was awarded the 2016 Air Force Young Investigator award, the 2017 NSF Career award and the 2017 Nobuhide Kasagi Award. He is co-founder of two MEMS based startup companies, both formed around innovations from his research lab.