Seminars

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.

Schedule
SAFL seminars are be held on Tuesdays, from 3:00 to 4:15 p.m. in the SAFL Auditorium. 

Recordings
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."

Seminar Notifications
To sign-up for our SAFL Seminar email list, click here.


Upcoming Seminars

Straub Award Ceremony and Distinguished Lecture

Presentation of the 2017 Lorenz G. Straub award
Award Recipient: Allison Goodwell
, University of Colorado Denver
Distinguished SpeakerEfi Foufoula-Georgiou, Distinguished Professor, Henry Samueli Endowed Chair in Engineering, Departments of Civil and Environmental Engineering
 and Earth System Science, University of California Irvine

Distinguished Lecture: Identification of physically-interpretable dynamical modes from big data: from turbulence to climate

Coherent spatio-temporal patterns (modes) in complex systems are regular features whose evolution is expected to be more predictable than the general background variability, whose impact on other parts of the system is often significant, and which reveal physical aspects of the system and its response to change. Two specific systems of interest exhibiting multi-scale variability and coherent spatio-temporal patterns are turbulence and climate. Here we will present a new methodology recently developed in our group, called rotated spectral Principle Component Analysis (rsPCA), and demonstrate its ability to robustly identify physically interpretable propagating modes even in the presence of noise. The innovation of rsPCA lies on (1) a wavelet-based implementation of sPCA using the continuous Morlet wavelet as a robust estimator of the cross-spectral matrices with good frequency resolution, and (2) a rotation of the complex-valued eigenvectors to optimize their spatial regularity (smoothness) using a regularization of their spatial Laplacian.  The combination of these two innovations improves interpretability and reduces the sensitivity of the extracted modes to noise and sampling variability as well as unmixes competing modes with similar amplitude within the same frequency band.  In this talk, the theory and application of rsPCA to a wave propagating example and to extracting dynamical modes from climate observations will be discussed.

SAFL Seminar: Sungyon Lee - UMN Mechanical Engineering

Talk Title: TBA
Sungyon Lee, Benjamin Mayhugh Assistant Professor, Mechanical Engineering

 

SAFL Seminar: Judy Yang - UMN Department of Civil, Environmental, and Geo- Engineering

Talk Title: TBA
Judy Yang, Assistant Professor, Department of Civil, Environmental, and Geo- Engineering, University of Minnesota

SAFL Seminar: Corey Markfort - Civil and Environmental Engineering, University of Iowa

Talk Title: TBA
Corey Markfort, Assistant Professor, Department of Civil and Environmental Engineering, University of Iowa

SAFL Seminar: Craig Hill - UMD Swenson College of Science and Engineering

Talk Title: TBA
Craig Hill, Assistant Professor, Swenson College of Science and Engineering, University of Minnesota Duluth

Past Seminars

Minnesota Stormwater Seminar Series - Lessons in Resilience from Monitoring Urban Stormwater Transportation Systems

Speaker

Robert G. Traver, Edward A. Daylor Chair in Civil Engineering & Director Center for Resilient Water Systems, Villanova University

Abstract: The Pennsylvania Department of Transportation (PennDOT) is working on a long-term project to rebuild and improve a major stretch of I-95 through an urbanized section of Philadelphia.  Central to this project is the need to meet Philadelphia’s Green City Clean Water stormwater regulatory requirements for a combined sewer area. To advise the design and maintenance PennDOT has contracted with Villanova and Temple Universities to conduct research on early phases of the project to inform the design of future phases.  Several stormwater management practices (bioswale and bioinfiltration) are being monitored from a hydrologic and geotechnical perspectives.  Stormwater management lessons learned from the research will be presented to include both performance and the challenges of a long-term transportation project.

Multi-source analysis of river networks and connectivity across scales

Paola Passalacqua, Associate Professor, Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin

Abstract: In the analysis of Earth-surface processes and response to changes in forcings and anthropogenic modifications, we are often challenged by the wide range of spatial and temporal scales that are involved and need to be accounted for. This is a challenge for numerical modeling as well and for collecting field observations representative of the system of interest across scales. The integration of remotely sensed data can help in this regard, as these data offer information at global scales and their spatial and temporal resolutions keep increasing. In this talk, I will focus on river systems and cover examples in which remotely sensed observations, numerical modeling, and field observations are integrated to gain a deeper understanding of system functioning and response to future changes. I will also discuss challenges we still face either due to missing information or lack of tools for data analysis and opportunities for future research.

About the SpeakerPaola Passalacqua is an Associate Professor of Environmental and Water Resources Engineering, in the Department of Civil, Architectural and Environmental Engineering at the University of Texas at Austin. She graduated from the University of Genoa, Italy, with a BS (2002) in Environmental Engineering, and received a MS (2005) and a PhD (2009) in Civil Engineering from the University of Minnesota. Her research interests include network analysis and dynamics of hydrologic and environmental transport on river networks and deltaic systems, lidar and satellite imagery analysis, multi-scale analysis of hydrological processes, and quantitative analysis and modeling of landscape forming processes. 

Mesoscale to microscale simulations for wind energy applications

Tina Chow, Professor, Department of Civil and Environmental Engineering, University of California Berkeley

Abstract: Wind turbines sit at the very bottom of the atmospheric boundary layer, where winds are highly turbulent and land-surface interactions may be strong. Variations in surface topography, from shallow depressions to steep mountains, also greatly affect flow development. High-resolution simulations of atmospheric flow are currently being developed to provide predictions for wind turbine micrositing and operational wind power forecasting. Here we present an overview of mesoscale to microscale simulations at real wind farms with complex terrain, including implementation of detailed models for turbine wake effects. The Weather and Research Forecasting (WRF) model is used here in grid nested configurations starting from the mesoscale (~ 10 km resolution) and ending with fine scale resolutions (~10 m) suitable for large-eddy simulation (LES) and comparison to field observations.

About the Speaker: Tina’s current research focuses on the atmospheric boundary layer, the lowest region of the Earth’s atmosphere, which is where we live and where weather events take place. Her research group aims to improve the numerical models used for weather prediction and air quality forecasts. She and her students have worked on predicting how winds are affected by complex mountainous terrain, how plumes spread in an urban environment, and how wind turbines respond in turbulent flow, among other applications. Tina received a B.S. in Engineering Sciences from Harvard University and M.S. and Ph.D. degrees in Civil and Environmental Engineering from Stanford University. She spent one year in the Atmospheric Sciences Division at Lawrence Livermore National Laboratory as a post-doctoral researcher. Tina joined the UC Berkeley Department of Civil and Environmental Engineering in 2005. At Cal, Tina teaches fluid mechanics, computer programming, and numerical methods to both undergraduate and graduate students.

Deforming bubbles in strong turbulence

Rui Ni, Assistant Professor, Department of Mechanical Engineering, Johns Hopkins University

Abstract: A persistent theme throughout the study of multiphase flows is the need to model and predict the detailed behaviors of all involved phases and the phenomena that they manifest at multiple length and time scales. When combined with background turbulent flows with similar multiscale nature, they pose a formidable challenge, even in the dilute dispersed regime. For many applications, from nuclear thermal hydraulics to bubble-mediated air-sea gas exchange, the dispersed phase often consists of many bubbles, bounded by surface tension and separated from the surrounding fluid by a deformable interface. Although many analytic and empirical models of multiphase flows have been formulated strictly for spherical or spheroidal particles with fixed shapes, in turbulent flows, finite-sized bubbles are constantly deforming with altogether different dynamics and momentum couplings over a wide range of scales. In this talk, I will share some ongoing efforts on developing new experimental facilities and techniques to simultaneously measure both the bubble deformation and surrounding turbulent flows in a Lagrangian framework. These preliminary results unveil different mechanisms of bubble deformation and breakup and will help to validate future closure models for Eulerian-Eulerian and Eulerian-Lagrangian two-fluids simulations in a turbulent environment.

About the Speaker: Dr. Ni recently joined the Johns Hopkins University as Assistant Professor of Mechanical Engineering in 2018. Before this position, he was the endowed Kenneth K. Kuo Early Career Professor at Penn State since 2015. He received his Ph.D. in Physics Department in 2011 from the Chinese University of Hong Kong and worked as a postdoctoral scholar at Yale and Wesleyan University. He won the NSF CAREER award in fluid dynamics and ACS-PRF New Investigator Award in 2017. His primary research focus is the development of advanced experimental methods for understanding gas-liquid and gas-solid multiphase flow as well as two-phase heat transfer problem. His other research interests include collective animal behaviors and physiological flows.

Simplified Stochastic Event Flood Modeling (SSEFM) for the Alcona Dam Hydroelectric Project

2018-2019 Nels Nelson Memorial Fellowship Ceremony:

Award recipient: Rochelle Widmer, MS student in the Department of Civil, Environmental, and Geo- Engineering

Keynote speaker: Cory Anderson, Water Resources Engineer, Barr Engineering

Abstract: One of the objectives and supporting strategies in FERC’s Strategic Plan for fiscal years 2014-2018 is to minimize risk to the public by using Risk-Informed Decision-Making (RIDM) for evaluating dam safety in parallel to traditional dam safety methods. Resulting risk estimates can be used, along with standards-based analyses, to decide if dam safety investments are justified. Consumers Energy Company (CEC) identified a concern at their Alcona Dam in Michigan regarding potential erosion of the unlined, earthen auxiliary spillway, and the potential subsequent failure of the dam during flood events more frequent than the inflow design flood (the PMF). However, given the possible consequences downstream, the estimated dam fragility, and the proposed and completed risk reduction measures, the risk may be low enough such that modifications to the auxiliary spillway are not warranted. Therefore, in 2017 CEC began a RIDM study of the Alcona Dam auxiliary spillway for submission to FERC.

RIDM requires a set of hydrologic hazard curves (HHCs) to estimate the overall risk. A Simplified Stochastic Event Flood Modeling (SSEFM) approach was used to develop the HHCs for Alcona Dam. The SSEFM method is a compromise between a purely deterministic approach which tends to be conservative and a fully stochastic, Monte-Carlo approach. The resulting HHCs are estimates of peak inflow rates for a range of annual exceedance probabilities (AEPs) from 0.01 to less than 1x10-7 for both cool-season (rain on snow) and warm-season (rain only) events. The SSEFM approach is the cornerstone of this RIDM study, allowing all other aspects of the study to relate important loading characteristics (peak water level, hydrostatic pressure, auxiliary spillway flow duration, etc.) to AEPs and therefore, a proper estimate of the risk.

About the speaker: Cory Anderson has about 10 years of experience in water resources engineering, working at Barr Engineering Co after graduating from UW in Madison in 2009. He specializes in hydrologic modeling, one- and to-dimensional hydraulic modeling, risk and uncertainty analysis, and probabilistic environmental modeling.

It rained two feet, now what?

William Hunt, William Neal Reynolds Distinguished University Professor & Extension Specialist, Department of Biological Agricultural Engineering, North Carolina State University

Abstract: Hurricane Florence dumped as much as 3 feet of water on parts of Southeastern North Carolina. This occurred only 1 year after massive flooding in Houston, Texas. Epic rainfall events, while still 'epic,' may no longer be considered infrequent. What does this mean for engineering design standards? What storms should we consider? Where is it OK to develop? What guidance does the engineering code of conduct provide? Insights to these questions and more are the focus of "It just rained 2 feet, now what?"

Regional Interdependence in Climate Change Adaptation: Sea Level Rise in the San Francisco Bay Area

2018-2019 Heinz G. Stefan Fellowship award ceremony
Award Recipient:
 Jackie Taylor, PhD Student in Civil, Environmental, and Geo- Engineering; advisors Miki Hondzo and Vaughan Voller

Keynote Speaker: Mark Stacey, Department Chair, Henry and Joyce Miedema Professor of Environmental Engineering, University of California- Berkeley

Abstract: Coastal communities around the world are facing a growing threat from sea level rise, which manifests itself as coastal flooding events of increasing frequency, magnitude and duration. Adapting to these changing conditions requires reconsideration of shorelines and other infrastructure systems, but  decisions by communities to take action in anticipation of future conditions both influence and are influenced by regional conditions and decisions. These interdependencies are a result of geographic interactions that emerge from either environmental processes or the function of infrastructure systems, and may be compounded by interactions between infrastructure systems, or through feedback with the environmental system.

In this talk, I will present a series of studies of how sea level rise will transform the San Francisco Bay Area, and the implications for regional adaptation planning. The interdependencies will be established through detailed analysis of tidal dynamics in combination with simulations of other infrastructure systems and the disruption of their function by coastal inundation events. Through these analyses, three distinct types of interdependence emerge, which will provide a foundation for consideration of the opportunities for and barriers to regional adaptation planning.

About the Speaker: Dr. Mark Stacey is the Henry & Joyce Miedema Professor and Chair in Civil & Environmental Engineering at the University of Califonia, Berkeley. He received his B.A.S. in Physics and Political Science and his M.S. and Ph.D. in Civil and Environmental Engineering from Stanford University. Throughout his career, his research and teaching have emphasized environmental physics, particularly the fluid mechanics of coastal environments. In the last decade, through the lens of sea level rise, he has focused on the interaction of environmental processes and infrastructure systems, including consideration of adaptation and resilience.

Improving parameterizations of sediment erosion in estuaries using high-resolution numerical simulations

Oliver Fringer, Professor, Department of Civil and Environmental Engineering, Stanford University

Abstract: I will present results of high-resolution, numerical simulations of fine sediment erosion in turbulent wave-current boundary layers.  The focus will be on parameters typically found in estuarine environments where wind waves are the dominant mechanism for fine sediment resuspension while mean currents by the tides and winds are responsible for mixing the sediment into the water column and making it available for horizontal transport. Parameterizations of sediment erosion in coastal models typically assume a turbulent wave boundary layer and a hydraulically rough sediment bed, which leads to more sediment erosion when waves are superimposed over tidal currents. However, in estuarine environments the waves can be laminar and the bed can be hydraulically smooth. Therefore, I will show that a laminar wave superimposed over a turbulent current can act to reduce the turbulence and bottom stress over part of the wave cycle, thereby reducing the bottom drag and sediment erosion. Owing to settling, I will also show that the near-bed suspended sediment concentration can be high enough to stratify the flow and reduce the vertical turbulent mixing, thus acting to further reduce the bottom drag and erosion.

 

About the Speaker: Oliver Fringer is professor in the Department of Civil and Environmental Engineering at Stanford University, where he has been since 2003. He received his BSE from Princeton University in Aerospace Engineering and then received an MS in Aeronautics and Astronautics, followed by a PhD in Civil and Environmental Engineering, both from Stanford University. His research focuses on the application of numerical models and parallel computing to the study of laboratory- and field-scale environmental flows to understand the physics of salt and sediment transport in lakes and estuaries, internal waves and mixing, and turbulence in rivers. Dr. Fringer received the ONR Young Investigator award in 2008 and was awarded the Presidential Early Career Award for Scientists and Engineers in 2009. 

An exploration of stream-riparian groundwater exchange during baseflow recession: Integration of hydrologic and geophysical data

Kamini Singha, Professor and Ben Freyrear Endowed Chair for Innovation and Excellence, Colorado School of Mines

Abstract: “Anomalous” solute-transport behavior, not explained by classical mathematics, has been observed at research and aquifer-remediation sites in diverse hydrogeologic settings. Anomalous behavior such as concentration rebound, long breakthrough tailing, and poor pump-and-treat efficiency have been explained by dual-domain mass transfer, where transport occurs between (1) a mobile domain, which consists of well-connected pores and fractures in aquifers, or a stream in watershed systems, and (2) a less-mobile domain, which consists of poorly connected pores and dead-end fractures, or a hyporheic zone. Despite recognition of the importance of non-Fickian transport, verification of its occurrence and inference of controlling parameters remain problematic. Conventional geochemical measurements preferentially sample from the mobile domain and thus provide only indirect information for the immobile domain and exchange between domains. Here, I present a petrophysical framework, experimental methodology, and analytical expressions that can be used to infer mass-transfer parameters from co-located breakthrough curves of mobile concentration and near-surface geophysical methods, specifically electrical resistivity (ER).  In particular, I’ll focus on stream-groundwater interactions, which are critical to ecosystem structure and function and water quality in many streams.  We’ll explore the controls on valley-bottom subsurface hydrology, which influences hyporheic exchange, using tracer tests and ER to inform on groundwater-surface water exchange.  Traditional characterization of hyporheic exchange (connectivity between streams and near-stream aquifers) relies upon solute tracer studies and a spatially sparse set of observations in streams and monitoring wells. ER methods image hyporheic exchange in both two and three-dimensions, and identify flowpaths at different temporal scales of stream connectivity. These data are an improvement over traditional methods, which would otherwise provide only reach-averaged values, or single observations in space.  Temporal moments of solute and ER data are used to compress trends into descriptive statistics and identify dominant solute transport processes (e.g., transient storage dominated, advection dominated, etc.).

 

About the Speaker: Kamini Singha is the Ben Fryrear Endowed Professor for Innovation and Excellence at the Colorado School of Mines, and serves as the Associate Department Head of the Department of Geology and Geological Engineering.  She worked at the USGS Branch of Geophysics from 1997 to 2000, and served on the faculty of The Pennsylvania State University as an assistant and then associate professor from 2005 to 2012.  Her research interests are focused in hydrogeology and environmental geophysics. Dr. Singha is the recipient of an NSF CAREER award, was awarded the Early Career Award from the Society of Environmental and Engineering Geophysics in 2009, served as the National Groundwater Association's Darcy Lecturer in 2017 and became a GSA Fellow in 2018.  She earned her B.S. in geophysics from the University of Connecticut in 1999 and her Ph.D., in hydrogeology, from Stanford University in 2005.

Resolved Simulations of Particulate Flows

Alvin G. Anderson award ceremony: 2018-2019 award recipient - Vinicius Taguchi, PhD Student in Civil, Environmental, and Geo- Engineering

Keynote Speaker: Andrea Prosperetti, Distinguished Professor of Mechanical Engineering, University of Houston

Abstract: New GPU-based computers and new algorithms now enable researchers to perform numerical simulations of particulate flows in which the particles are resolved and the hydrodynamic forces on them are obtained from first principles rather than correlations. One such method will be briefly outlined and then several applications described: kinematic waves and the statistics of various quantities in a fluidized-bed-like system, the behavior of tetrads (four-particle groups), the rotational dynamics and thermal wakes of particles immersed in an incident turbulent flow and others. This work will be placed in the context of existing methods and will be motivated by outlining some outstanding problems in this general area. The promises and obstacles of the paths opened by this general area of research will be described.

 

About the Speaker: Andrea Prosperetti is a Distinguished Professor of Mechanical Engineering at the University of Houston, which he joined after 30+ years as CA Miller Professor of Mechanical Engineering at the Johns Hopkins University, where he still holds the title of Homewood Professor. He is also continuing his 20-year old part-time appointment as Berkhoff Professor of Applied Physics at the Universty of Twente in the Netherlands. Prosperetti's work is in the general area of multiphase flow: bubble dynamics and bubbly flows, particulate flows and applied mathematics. He is author or co-author of about 250 refereed journal papers and two books. He recently stepped down as editor in chief of the International Journal of Multiphase Flow, which he led for a decade. He was elected to the National Academy of Engineering in 2012.