The Troy Lab at Purdue University investigates hydrodynamic processes and related engineering and biological applications in coastal waters. Our work focuses on improving our understanding of how substances are transported in lakes and oceans, how coastlines evolve in response to different hydrodynamic conditions, and how coastlines can be engineered to be more resilient. We have a primarily observational approach, carrying out field and laboratory experiments in the Burke Laboratory facilities as well as in our “natural laboratory,” Lake Michigan.
In order to better predict and understand how contaminants, organisms, and sediment are transported through coastal waters, our lab studies the underlying physical processes responsible for this movement. Our work in this theme spans a broad spectrum of transport processes, ranging from large-scale circulations and basin-scale internal waves down to fine-scale turbulent mixing and instabilities. With a primarily observational approach, we collect and analyze direct measurements of these processes in both our laboratory research flumes as well as in Lake Michigan.
The mixing efficiency of interfacial waves breaking at a ridge. Part I: Overall mixing efficiency
Hult, E.L., C.D. Troy, and J.R. Koseff Journal of Geophysical Research, VOL. 116, C02003 PDF Online Article
Since their arrival at the turn of this century, invasive quagga mussels have dramatically altered the food web in Lake Michigan. Quagga mussels now cover the bottom of much of Lake Michigan, particularly deeper waters, with densities exceeding 10,000 mussels per square meter in certain locations. As prolific filter-feeders, quagga mussels can filter up to several liters of water per day. The increased water clarity of Lake Michigan may seem like a good thing (Lake Michigan’s water clarity now rivals Lake Tahoe), but these hardy “ecosystem engineers” have had a dramatic effect on Lake Michigan’s ecosystem, causing species extinction, alterations to nutrient cycling, and benthic substrate changes.
Near-inertial internal waves are ubiquitous features in both large lakes and oceans. In large thermally-stratified lakes such as Lake Michigan, these basin-scale waves create strong near-surface currents that rotate clockwise (in the northern hemisphere) over a near-inertial period (~17.5 hours for Lake Michigan). The influence of these basin-scale waves, for which the thermocline movement represents a spinning coin, is particularly strong in the offshore waters, where the spiraling near-surface currents can have tide-like regularity.
This project was developed during my sabbatical at the École Polytechnique Fédérale de Lausanne (EPFL) in Lausanne, Switzerland, where I was hosted by Dr. Johny Wüest. The objectives of the project were to quantify seasonal variations in vertical mixing in the lake, making use of the L’Explore Platform, and to link these observations of vertical mixing with the overall energetics of the lake.
In order to refine models and calculations that can lead to more resilient shorelines, our lab studies the interactions between waves, coastlines, and coastal structures. This includes developing and improving models that capture shoreline changes associated with waves, currents, and water level fluctuations. This work is heavily focused on the sandy southern shoreline of Lake Michigan, where we carry out field experiments and analysis. We perform in-situ experiments that measure both the lake hydrodynamics (waves, currents, and turbulence) using acoustic instruments as well as morphodynamic changes to the lake shoreline and bottom. Additional work is performed in Purdue’s 50m wave basin, where we can test coastal structures and wave attenuators.
An Integrated Physical-Social-Community (PSC) Approach for Sustainable Shore Protection, Beach Integrity, and Bluff/Dune Stabilization Along Lake Michigan
Recent record-high water levels across the Laurentian Great Lakes have shoreline communities scrambling to protect beaches, property, and infrastructure from rapid and widespread erosion. This current situation, and the uncertainty associated with lake levels in the future, underscores the need for comprehensive shoreline management strategies that will create resilient shorelines capable of buffering future conditions. However, shoreline protection strategies must be carefully implemented, ideally in a coordinated manner, since “hard” protection measures such as sea walls and revetments generally have large impacts on neighboring shorelines.
Also motivated by the recent high water levels in the Laurentian Great Lakes, this project aims to collect and disseminate timely shoreline data and analysis to Indiana shoreline managers and residents. For this project, we will be performing shoreline surveys using Purdue’s LiDAR-equipped unmanned aerial vehicle, as well as analyzing existing historical LiDAR data to assess Indiana’s shoreline changes in the context of historical changes.
In collaboration with Illinois-Indiana Sea Grant and the Höök Lab at Purdue, our lab has co-deployed and maintained NDBC Buoy 45170 since it was launched in 2012. This Lake Michigan buoy, located about 2 miles offshore from Michigan City, IN, measures standard meteorological parameters (wind speed, air temperature, etc.) as well as surface and subsurface lake temperatures, wave height, and wave direction. The buoy reports data in real time to both the NDBC buoy website as well as a dedicated Sea Grant website. It is typically deployed in early May and retrieved as late as November. This buoy currently provides the only wave measurements along Indiana’s shoreline, which are the largest waves in Lake Michigan.
This project focuses on the development of renewable, water-driven power generation technologies. We are developing and testing both hydrokinetic and wave power devices for riverine and coastal power generation, leveraging Purdue’s 50m long tow and wave basin.
Our lab is passionate about teaching, and always working to improve our collective abilities to teach young engineers. To that end, our pedagogical research thrust has targeted the development and refinement of effective teaching strategies in large classrooms. Research projects and efforts have included the development and assessment of flipped instruction techniques for large classrooms, the development of open-ended laboratory exercises, and the incorporation of writing exercises in lower-level engineering courses.
Writing to Learn Engineering: Identifying Effective Techniques for the Integration of Written Communication Into Engineering Classes and Curricula
Proficiency in technical writing is a highly desirable attribute for engineering graduates, and improvement of communication skills among undergraduate engineering students can help enhance the competitiveness of U.S. technical talent in an increasingly global engineering market. This project responds to the need for improved communication skills in engineering by directly addressing challenges associated with incorporating writing-based instructional techniques in traditional technical classes.
In this project, we are developing training materials to help operators of municipal storm sewer systems (MS4) reach compliance with IDEM’s new MS4 permit. This permit requires additional training for agency staff, contractors, and engineers. Training materials that we are developing include handouts, videos, and assessments that are readily accessible by MS4 permit agencies.