Event

The Department of Earth & Environmental Science

University of Pennsylvania

Invites you to attend a EES Seminar Series

Friday, November 1, 2024 - 3:00 PM

"Mixing and Melting in Homogeneous Isotropic Turbulence"

High levels of turbulence can increase instantaneous localized shear and in turn facilitate transport across interfaces. For example, the uprush in the coastal nearshore can be characterized as bore-advected offshore wave-generated turbulence; resulting sediment suspension in the swash is observed to be greater than would be predicted by traditional mean shear models. To isolate the role of turbulence in transport processes, we conduct laboratory experiments in custom-designed facilities that generate zero mean flow homogeneous isotropic turbulence via randomly actuated synthetic jet arrays. We use particle image velocimetry and laser induced fluorescence to characterize turbulence and mass transport. In this talk, we explore the boundary layer that develops when homogeneous isotropic turbulence interacts with a sharp density stratification and with ice.  At a density interface, we explore conditions of flow and density that lead to the development of internal waves and encourage interfacial mixing. For ice experiments, we evaluate how turbulence can increase melt rates even at low temperatures through rapid stirring of meltwater plumes. These various boundaries each highlight the ability of turbulence to drive evolution of critical environmental systems.

Dr. Blair Johnson

Assistant Professor in Civil, Architectural & Environmental Engineering

University of Texas Austin 

Blair Johnson is an Assistant Professor in Civil, Architectural & Environmental Engineering at the University of Texas at Austin.  Her research focuses on environmental fluid mechanics and experimental methods.  Dr. Johnson completed her B.S. (2008) at Johns Hopkins University in Civil Engineering, with a concentration in Structures and a minor in Piano at the Peabody Conservatory of Music.  She attended Cornell University where she received her M.S. (2012) and Ph.D. (2016) in Environmental Fluid Mechanics & Hydrology in Civil & Environmental Engineering.  In 2012 she was a visiting researcher at the Instituto de Hidraulica Ambiental (IH Cantabria) in Santander, Spain.  Following graduate school, she held a Postdoctoral research position in Mechanical & Aerospace Engineering at Arizona State University from 2016-2017.