Seminars

seminar room safl

Every other week 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. unless otherwise noted. Join us in the SAFL Auditorium or via Zoom.

 
Spring 2024 Seminar Series
Tuesday, Jan 23-Katey Anthony
Tuesday, Feb 6th-No Seminar 
Tuesday, Feb 20th-Neal Iverson
Tuesday, March 12- Jennifer Stucker 
 
Tuesday, March 26th-Mike Shelley
Tuesday, April 9th-Sergio Fagherazzi
Tuesday, April 23rd-Ruben Juanes
Tuesday, May 7th-Walter Musial

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

There are no upcoming events matching your criteria.

Past Seminars

Motion of sediment at the bed of rivers

Edward Silberman Fellowship Award Ceremony
2018-2019 Edward Silberman Fellowship Recipient: Santosh Kumar, PhD Student in Mechanical Engineering (advisor: Jiarong Hong)
Keynote Speaker: Mark Schmeeckle, Professor in the School of Geographical Sciences and Urban Planning, Arizona State University

Abstract: The movement of sediment at the bed of a river or a laboratory flume can be viewed by the human eye and recorded by high-speed cameras. Velocimetry techniques can simultaneously record details of the turbulent fluid. It is, thus, surprising that many of the details of this sediment movement, which shapes much of earth’s surface, remains unknown or controversial. Bed load sediment is often thought to move in a series of hops called saltation. However, tracking of particles using high-speed video reveals that saltation models do a poor job of predicting the full distribution of grain motions; many grains move more slowly and for shorter distances than by saltation. The video particle tracking results also show that the temporal variability of grain motion due to turbulence is large at all mean transport rates. New field and lab evidence also suggests that the detailed structure of grain-to-grain contacts within the bed plays a key role in determining sediment transport rates. Furthermore, grain contact structure differs dramatically at different locations and at different times. Laboratory measurements as well as detailed numerical simulations of turbulence and particle motion will be presented to explain what is known about bed load motion in rivers and how that leads to the formation of ripples, dunes, bars, and channels. 

Globalization of land and water resources to meet societal food and energy needs

Paolo D'Odorico, Professor, Department of Environmental Science, Policy, and Management, University of California Berkeley

Abstract: The increasing global demand for farmland products by the growing and increasingly burgeoning human population is placing unprecedented pressure on the global agricultural system and its water resources. Many regions of the world, that are not self-sufficient because of chronic water scarcity or lack of suitable agricultural land, strongly depend on the imports of agricultural commodities and associated embodied water. Trade and foreign land acquisitions are leading to a displacement of land use and a disconnection between human populations and the water resources they rely on. These phenomena are reshaping the patterns of water dependency through teleconnections between consumers and production areas. Competition in water use for food and energy production constitutes the core of an emerging debate that is stimulating new questions on the environmental, ethical, economic, and policy implications of human appropriation of water resources. This seminar will examine the ways water resources may constrain food and energy production and the ability to meet the growing societal needs.

About the Speaker: Paolo D’Odorico is Professor of Hydrology at the University of California, Berkeley. He received his Ph.D. from the university of Padua (Italy), has been a postdoc at Princeton, and a faculty member at Texas A&M and the University of Virginia. His research focuses on the role of hydrological processes in the functioning of terrestrial ecosystems and societies. His work has analyzed the coupling between hydrological processes and the biota, and contributed to the field of ecohydrology. Through field observations and modeling he is studying new mechanisms of desertification and factors contributing to the resilience of ecosystems at the desert margins. He is currently investigating the global patterns of water use for food and energy production and their impacts on water equity, societal resilience, and
food security.

Breakup of Crude Oil-Dispersant Mixtures into Subsurface and Aerosolized Droplets

Joseph Katz, William F. Ward Sr. Distinguished Professor, Department of Mechanical Engineering, Johns Hopkins University

Abstract: A series of laboratory-scale experiments examine the generation of both subsurface and airborne crude oil droplets by breaking waves, bursting of bubbles, subsurface plumes and raindrop impact. For waves, premixing the oil with dispersant (Corexit 9500A) reduces the droplets sizes to the micron- and submicron-scales, and changes the slope of their size distribution. Without dispersant, the characteristic oil droplet diameters can be predicted based on the relevant turbulence scales. Once entrained, the temporal evolution of concentration and size distribution of these droplets can be modeled as a combined effect of turbulent diffusion and buoyant rise. With dispersant, the droplet sizes are much smaller than the turbulence scales, in part due to tip-streaming at the oil-water interface. Furthermore, the droplet fragmentation persists long after the wave breaking. Aerosolization of oil is caused both by the initial splash and by subsequent bubble bursting, as entrained bubbles rise back to the surface. Dispersants increase the airborne nano-droplet concentration by orders of magnitude, raising health concerns. The shape of subsurface crude oil plumes in cross flow is affected by the droplet sizes and their interaction with the plume’s counter-rotating vortex pair. Hence, dispersants modify the entire plume geometry and the spatial distribution of droplets in it. The near-field plume breakup processes, which determines the droplet sizes, are probed by matching the refractive index of silicon oil with that of sugar water.  The measurements show that the droplet sizes, location of breakup, and even the plume scales are Reynolds- and Weber-number dependent. The frequent generation of compound oil droplets and ligaments, which contain smaller water droplets, has significant effect on the oil-water interfacial area.

The Era of Data Rich Hydrology

50th presentation of the Lorenz G. Straub award ceremony
Award Recipient:
 Conrad Wasko, University of New South Wales
Distinguished Speaker Rafael L. Bras, Provost and Executive Vice President for Academic Affairs, Professor, Civil and Environmental Engineering and K. Harrison Brown Family Chair in the School of Earth and Atmospheric Sciences, Georgia Institute of Technology

Abstract: Until late in the 20th century hydrology, and many other Earth Sciences, developed in a limited data environment. For the most part, researchers and practitioners availed themselves of data of very low resolution in time and space. In hydrology, that meant point observations of fluxes like precipitation and evaporation and state variables like soil moisture, temperature and topography. Those observations were rarely hourly, sometimes daily and more commonly weekly and monthly. That situation forced hydrologists to rely on significant data extrapolation and on conceptual mathematical models designed to capture broad system behavior. That situation began changing rapidly at the end of the 20th century. In the 1990’s the United States (NASA) started implementing the Earth Observing System, some two dozen satellites have or continue to observe Earth and its environment at unimaginable resolution in time and space. In year 2000 the Shuttle Radar Topography Mission mapped the world at resolutions of 30 meters or less. That was a watershed moment for hydrology, it was no longer necessary to conceptualize and deal with lumped aggregated representations of basins. All of a sudden, and to this day, we have more data than we know how to use properly. This richness comes with challenges. The data is unwieldy, its errors structures are different, old models are of little guidance and new representations to match data availability are required. The tools needed to handle the data are different: the “big data” analysis era is with us. This paper explores that evolution in data and its use in hydrology. It will illustrate the challenges using analysis of precipitation, soil moisture, topography and temperature data, among others. The message is that the wealth of data now leads our understanding and to exploit that newly found information properly we cannot rely strictly on statistical/analytical procedures but must fall back on our understanding of hydrology/meteorology. In that sense, not much has changed.

About the Speaker: Rafael L. Bras is provost and executive vice president for Academic Affairs at the Georgia Institute of Technology. He is a professor in the School of Civil and Environmental Engineering and the School of Earth and Atmospheric Sciences where he holds the K. Harrison Brown Family Chair. 

Before becoming provost, Bras was a distinguished professor and dean of the Henry Samueli School of Engineering at UC-Irvine. For 32 years, he was a professor at the Massachusetts Institute of Technology where he was chair of the faculty, head of the Civil and Environmental Engineering department, and director of the Ralph M. Parsons Laboratory. He has served as advisor to many institutions including: Engineering Directorate, National Science Foundation; Board of Atmospheric Sciences and Climate, National Research Council; Earth Systems Sciences and Applications Committee of NASA and NASA Advisory Committee; National Academy of Sciences; United States Secretary of Energy, and the academic departments of prestigious American and international universities.

He is a distinguished member of ASCE, fellow of AGU, AMS, ASCE and AAAS, an elected member of the U.S. National Academy of Engineering, the Academy of Arts and Sciences of Puerto Rico and the Academies of Engineering and Sciences of Mexico. He holds an honorary degree from the University of Perugia in Italy. His awards include the Hispanic Engineer National Achievement Award Hall of Fame, AGU Horton medal, NASA Public Service Medal, and the Clarke Prize, among others.

Vortex wake dynamics: the surprising connections between bat flight and tidal energy harvesting

Kenny BreuerProfessor of Engineering and Professor of Ecology and Evolutionary Biology at Brown University

Abstract: Strong vortices shed into the wake by thin, compliant structures are characteristic of a wide variety of high Reynolds number flows. In this talk I will describe three configurations dominated by strong vortical wakes.  To kick things off, I will provide a sampling from our long-term effort to characterize, understand and model the aeromechanics that underpin the incredibly agile and maneuverable flight of bats.  This work has inspired two other research threads that have become prominent in recent years, Firstly, I will show measurements that support a model for a universal scaling of the growth of the leading-edge vortex from the sharp leading edge of a compliant plate. Lastly I will describe our work on hydrokinetic energy harvesting that harness the unsteady dynamics of the leading-edge vortex.

About the Speaker: Kenny Breuer received his Sc.B. from Brown University in Mechanical Engineering (1982) and his Ph.D. from MIT in Aeronautics and Astronautics (1988). He spent two years back at Brown as a Post Doctoral Fellow in Applied Mathematics and nine years on the faculty at MIT, before finally returning to Brown in 1999, where he is currently Professor of Engineering. In 2010 he received a courtesy appointment as Professor of Ecology and Evolutionary Biology. From 2011 to 2014 he served as Senior Associate Dean of Engineering for Academic Programs.

Professor Breuer’s research interests are in the broad field of Fluid Dynamics and cover a wide range of diverse topics. At the micron-scale, he has been active in the development of diagnostic techniques for micron-scale and near-surface velocimetry, in the characterization of slip flows, the mechanics of bacterial motility and flagellar and cilliar mechanics and the nanoscale flow near a moving contact line. At the macro-scale, he has worked on the mechanics of animal flight (particularly bat flight), vortex interactions with compliant structures and, most recently, energy harvesting from fluid flows.   With his students and collaborators, he has co-authored over one hundred peer-reviewed articles in scientific journals, numerous book chapters, and has edited several books, including Microscale Diagnostic Techniques (Springer, 2004).

On Atmospheric Boundary Layer, Plants and Climate

Amilcare Porporato, Professor in the Department of Civil and Environmental Engineering and the Princeton Environmental Institute, Princeton University

Abstract: We discuss recent results on the mixed-layer modeling of the atmospheric boundary layer to investigate the role of surface fluxes due to hydrologic controls by plants and soil moisture. We focus on the initiation of moist convection taking place when the atmospheric boundary layer reaches the lifting condensation level (LCL) in conditions of high convective available potential energy (CAPE). We show how transpiration regimes of different photosynthetic types (e.g., C3, C4 and CAM) may imply different controls of such occurrences.

The daily cloud cycle associated to these processes is then investigated globally using satellite observations and reanalysis data and compared with results from climate models. We show that typical afternoon cloud peaks over land are poorly reproduced by most climate models, resulting in biases in the Earth’s energy balance leading to overestimation of radiation in most climate models.

About the Speaker: Amilcare Porporato currently is the Thomas J. Wu ’94 Professor of Civil and Environmental Engineering and the Princeton Environmental Institute at Princeton University. He earned his Masters Degree in Civil Engineering (summa cum laude) in 1992 and a Ph.D. in Hydraulic Engineering in 1996 from the Polytechnic of Turin, where he was appointed as a researcher and then associate professor. He moved to Duke University in 2003, where he became the Addy professor in the Department of Civil and Environmental Engineering with a secondary appointment with the Nicholas School of the Environment. His main research interests regard nonlinear and stochastic dynamical systems, hydrometeorology and soil-atmosphere interaction, soil moisture and plant dynamics, soil biogeochemistry, ecohydrology and environmental thermodynamics. Porporato has been Editor of Water Resources Research (AGU) (2004-2009) and Hydrological Processes (2011-2017). He is also member of the editorial board of Advances in Water Resources and the Hydrologic Science Journal.

Turbulence and Thermal Structure in the Upper Ocean: LES Studies

Sutanu Sarkar, Professor, Mechanical and Aerospace Engineering, University of California San Diego

Abstract: The upper layer of the ocean participates directly in the exchange of momentum, heat and moisture with the atmosphere. We consider three examples of upper-ocean flow and heat transfer in the present contribution.  These examples illustrate wind-driven entrainment in a stratified fluid, stratified shear flow turbulence and its response to surface forcing, and the lateral circulation in a frontal jet between two water masses of different density that develops into a gravity current. Our tool is large eddy simulation (LES) which is increasingly being used to examine turbulent transport and mixing in the ocean. We discuss how buoyancy and rotation affects the spatial structure and temporal evolution of turbulent fluxes, and thereby the distribution of momentum and heat in the upper ocean.

About the Speaker: Sutanu Sarkar received his B. Tech from IIT Bombay, M. S. from Ohio State University and Ph. D. from Cornell University. After 4 years as a staff scientist at ICASE, NASA Langley Research Center, he joined UCSD where he is currently the Blasker Professor of Engineering in the department of Mechanical & Aerospace Engineering (MAE) and an affiliate professor at the Scripps Institute of Oceanography. He was Chair of MAE from 2009-2014. He has broad interests in turbulence simulation and modeling and has worked in problems concerning the environment, energy, aerospace and propulsion. His current research interests are turbulence and mixing in the ocean, wakes and boundary layers of engineered structures in the natural environment, and renewable energy. He has received a NASA group achievement award (1994), the Bessel Award from the Humboldt Foundation (2001), and was elected Fellow, American Physical Society (2006), Associate Fellow, AIAA (2009) and Fellow, ASME (2010).

Trees, pets, and people: a watershed approach to understanding urban water quality

Sarah Hobbie, Professor, Ecology Evolution and Behavior, University of Minnesota

People in and downstream of cities rely on lakes and rivers for a variety of services. Despite progress made in reducing point sources of pollution to urban surface waters, these waters continue to be impaired by so called “non-point” pollution, particularly excessive inputs of nitrogen (N) and phosphorus (P). We’ve been taking a watershed approach to understanding urban water pollution, quantifying inputs and outputs of N and P in urban subwatersheds of the Mississippi River, in Saint Paul, Minnesota, USA towards improving management of urban nutrient pollution. Household actions of lawn fertilization and pet ownership contributed the majority of watershed N and P inputs, respectively. N and P exhibited contrasting dynamics within watersheds. In contrast to many non-urban watersheds that exhibit high P retention, these urban watersheds have high street density that enhanced transport of P-rich materials like tree leaves from landscapes to stormwater, likely contributing to surface water degradation. High apparent N retention likely resulted from unmeasured watershed N losses to the atmosphere and groundwater. These contrasting dynamics suggest that N management should emphasize reducing watershed inputs from residential fertilizer, while P management should focus on reducing watershed P inputs and transport from vegetated landscapes to streets and storm drains through leaves and lawn runoff.

To watch a live videostream (if available) click here. 

From basins to blades: an overview of national research priorities for sustainable hydropower development and operation

Adam Witt, Hydropower Systems Research Engineer, Oak Ridge National Laboratory

Hydropower is a well-established, low-cost renewable energy generation technology supplying nearly 18% of electricity consumed globally.  A hydropower facility interacts continuously with the surrounding water resource environment, causing alterations of varying magnitude to the natural flow of water, energy, fish, and sediment upstream and downstream.  A universal challenge in facility design and operation is balancing the extraction of useful, carbon free energy and power system services from a stream while maintaining ecosystem processes and natural environmental function. 

In this seminar, I will highlight several research projects underway at Oak Ridge National Laboratory, a science and energy laboratory conducting hydropower research for the Department of Energy.  Our research is committed to promoting sustainable energy production in healthy ecosystems through technology development, systems analysis, and decision support, spanning scales from basins to blades.  At the basin scale, I’ll summarize recent modeling work to optimize a cascade of large hydropower plants for maximum energy production and minimization of total dissolved gas generation.  At the blade scale, I’ll discuss research efforts to define a new class of low-impact, small modular hydropower technologies, including additively manufactured hydropower turbine systems created on one of the world’s largest 3D printers. 

 

To watch a live videostream (if available) click here. 

Use of Hollow Glass Spheres in Lightweight Cements

Clara Mata, Senior Product Development Specialist, 3M

Cementing across highly depleted zones and weaker formations requires low density cement systems capable of reducing the hydrostatic pressure of the fluid column during cement placement. If wellbores encounter weak or depleted zones, standard cement cannot be used because the bottom-hole pressure will exceed the pressure gradient and cement will get lost to the formation. Service companies offer cement solutions made light enough to circulate in such situations while retaining the ability to withstand down-hole conditions and maintaining adequate compressive strength to meet regulatory guidelines. Lightweight cements can be achieved using water extension, foamed cement or lightweight microspheres. The seminar focuses on the use of lightweight microspheres as density reducing agent. Selected experimental data comparing different types of hollow microspheres and guidelines on the selection of the appropriate microsphere grade will be discussed.