Recent developments in measuring the smallest velocity scales
George Washington University
Abstract
The velocity length-scales at interfaces are often the smallest encountered in many flows. They drive important phenomena, such as skin friction, heat and mass transfers, etc. For example, in high-Reynolds number wall-bounded flows the viscous wall unit can be on the order of the micrometer along the hull of ships or in the core of nuclear reactors; in some boiling conditions, micro-layers can be only a few micrometers thick. Historically, it has been challenging to directly probe flows in such conditions, which has led to much empiricism in numerical models.
This presentation will present recent developments in optical diagnostics to measure wall shear and flows in the direct vicinity of walls. The developments include the extension of molecular tagging velocimetry (MTV) to measure instantaneous wall shear stress in high-Reynolds number flows, the adaptation of Fourier integral microscopy (FIMic) to MTV and particle tracking velocimetry, and the generalization of FIMic to plenoptic 3.0.
About the speaker
Dr. Philippe M. Bardet’s research group is developing non-intrusive laser diagnostics for probing complex flows. Notably, Dr. Bardet’s group has advanced Molecular Tagging Velocimetry to measure wall shear stress directly in high-Reynolds number flows and applied Fourier Integral Microscopy, a new form of plenoptic imaging, or integral microscopy, to velocimetry. Recently, his group has extended the applicability of this plenoptic approach to macroscale, naming the technique plenoptic 3.0. He has led several in-situ experimental campaigns where his team instrumented large experimental facilities with custom diagnostics. His research is applied to naval hydrodynamics and nuclear thermal hydraulics.
He is the director of the ONR Consortium on Naval Enterprise Pathways (CoNEP), a large effort to increase workforce development in the Washington, DC area through innovative research. He is also the director of the newly formed DC Computational Imaging Research Center (DC-CIRC), a partnership between industry, National Laboratories, and academia to push the limits of computational imaging techniques for fluid mechanics.
Dr. Bardet teaches courses in Fluid Mechanics, Thermodynamics, Electronics, Experimental Methods, and Optics.
