Elie Bou-Zeid
Director, Program in Environmental Engineering and Water Resources
Princeton University
Seminar Information
Engineering Building Unit 2 (EBU2)
Room 479
Seminar Recording Available: Please contact seminar coordinator, Jake Blair at (j1blair@ucsd.edu)
The overwhelming majority of studies of wall-bounded turbulence examine steady and barotropic flows; that is the pressure gradient driving the flow is (quasi) steady and does not vary with distance from the wall. These conditions are the rare exception in many real-world flows, particularly in geophysical and environmental settings. In this talk, we focus on flows outside of this canonical framework using large-eddy simulations of wall-bounded flow with time-varying (unsteady) or height-varying (baroclinic) pressure forcings. For the unsteady ABL, turbulence is found to be highly out of equilibrium with the mean flow when the forcing time scale ~ turbulence time scale, suggesting a need for turbulence models with memory in such flows. However, the mean flow dynamics for cases where a quasi-steady turbulence-mean equilibrium is observed can be reduced to a simple damped oscillator model. For the baroclinic simulations, the mean flow can also be approximated well using novel analytical solutions. The resulting mean and turbulence profiles are strongly influenced by the strength and direction of the baroclinicity, which also interacts with the rotation (depending thus on the Rossby number). Baroclinic boundary layers can thus display vast deviations from the canonical log laws observed under barotropic conditions, with implications in many areas, particularly wind energy.
Elie Bou-Zeid’s research focuses on the highly turbulent flows in the lowest layer of the Earth’s atmosphere, the atmospheric boundary layer. He blends numerical and experimental data to develop a deeper understanding of the physics of atmospheric flows and to derive reduced theoretical models that can be used in a range of applications. His fundamental work gravitates towards the lesser explored dynamics that emerge over heterogeneous and complex surfaces, under unsteady and non-equilibrium conditions, and with baroclinic or other large-scale thermal forcing of the flow. His applications have mostly centered around flows of relevance to the urban environment, the hydrological cycle, and the renewable energy transition. Bou-Zeid is a Professor of Civil and Environmental Engineering at Princeton University, the Chair of the Committee on Boundary Layers and Turbulence of the American Meteorological Society, and editor of the Journal of the Atmospheric Sciences. He holds a bachelor’s degree in Mechanical Engineering from the American University of Beirut (Lebanon) and a Ph.D. in Environmental Engineering from the Johns Hopkins University (USA).