The Troy research group focuses on the environmental fluid mechanics of surface waters, which broadly defined is the study of naturally-occurring and engineered water flows, often with environmental applications. We are currently focusing primarily on lakes and reservoirs, both big (Lake Michigan) and small, with a variety of physical, biological, and chemical applications. Our work is closely related to fundamental fluid mechanics, physical oceanography, physical limnology, and meteorology.
Lake Michigan - overview
A primary research focus of the Troy research group is the hydrodynamics of Lake Michigan. Our research group uses a combination of field experiments, numerical modeling (computational fluid dynamics), and analytical work in order to better understand circulation, thermal structure, and turbulent mixing in Lake Michigan. Some applications of our work include: larval fish recruitment; interannual variability in circulation and thermal structure; internal waves; small-->large scale dispersion; nutrient loading and river plumes; and the effect of invasive quagga mussels on water quality. We have received funding from the National Science Foundation, the Great Lakes Fisheries Commission, the Great Lakes Fisheries Trust, Illinois-Indiana Sea Grant, and other organizations.
Numerical modeling - computational fluid dynamics (CFD)
We use the Stanford Unstructured Navier-Stokes Terrain-Adaptive Simulator (SUNTANS) from Stanford University. The model is forced with historical meteorological data and run on Purdue University's high-performance computing clusters. Applications of our model include simulation of interannual variability in hydrodynamics and thermal structure. Some sample output from our model is provided in the visualization below, for an idealized test case: numerical simulation of classic upwelling along Michigan coast, set up by impulsive wind from the north (following the test case of Beletsky et al., 1997):
Benthic boundary layer exchange processes
The benthic boundary layer (BBL) is the interfacial water layer between the bottom sediment and the overlying hypolimnion. Although the BBL is often only a small percentage of the total water depth, it plays a vital role in nutrient and pollutant exchange, sediment deposition and resuspension, and biological growth and development. All of these activities are driven by benthic exchange processes, including diffusive mixing and advective transport. Measuring these benthic exchange processes in situ allows us to collect data that is imperative for understanding and modeling the BBL, giving us insight into processes that are important to engineers, biologists, limnologists, and oceanographers alike. Currently, we are studying the effects of benthic exchange processes on the filtration capabilities of invasive quagga mussels in Lake Michigan.
Example of near-bed currents measured in Lake Michigan:
River plume characterization
This work aims to characterize the chemical, biological, and physical properties of river plumes in Lake Michigan. Boat-based sampling has been conducted for Lake Michigan river plumes, and ongoing work aims to describe the role of these plumes in nutrient and contaminant delivery to Lake Michigan. Two sample boat-based river plume maps are shown below (images from Rebecca Essig, Ph.D. student):