Wed, Nov 11, 2020 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Speaker: Mark Hodes, Tufts University
Talk Title: Asymptotic Nusselt Numbers for Internal Flow in the Cassie State and Their Application to Thermal Management of Electronics
Abstract: We consider laminar, fully-developed, Poiseuille flows of liquid in the Cassie state through diabatic, parallel-plate microchannels symmetrically textured with isoflux ridges. Through the use of matched asymptotic expansions we analytically develop expressions for dimensionless (apparent hydrodynamic) slip lengths and variously-defined Nusselt numbers. Our small parameter (ε) is the pitch of the ridges divided by the height of the microchannel. When the ridges are oriented parallel to the (fully developed) flow, we quantify the error in the Nusselt number expressions in the literature and we provide a new closed-form result. The latter is accurate to O(ε2) and valid for any solid (ridge) fraction, whereas those in the current literature are accurate to O(ε) and break down in the important limit when solid fraction approaches zero. When the ridges are oriented transverse to the (periodically fully-developed) flow, the error associated with neglecting inertial effects to find the slip length is shown to be O(ε3Re) where Re is the channel-scale Reynolds number based on its hydraulic diameter. The corresponding Nusselt number expressions are new and their accuracy is shown to be dependent on Reynolds number, Peclet number and Prandtl number in addition to ε. They're compared to numerical results from the literature. In concluding this talk, we will show how the results can be used to design enhanced liquid-metal cooling solutions for microelectronics.
Biography: Marc Hodes earned his BS, MS, and PhD degrees in Mechanical Engineering from the University of Pittsburgh, the University of Minnesota and the Massachusetts Institute of Technology, respectively. He spent 10 years at Bell Labs Research (Murray Hill, NJ) and has spent extended periods in residence at the National Institute of Standards and Technologies (NIST), the University of Limerick and Imperial College London. He joined the Department of Mechanical Engineering at Tufts University in 2008 where he is a Professor and the Director of Graduate Studies. His Groups research there has been funded by government agencies, e.g., NSF, DARPA and DoE, and industry, e.g., Huawei and Google. Research interests are in Transport Phenomena and, over the course of his career, four thematic areas have been addressed: 1) the thermal management of electronics, 2) mass transfer in supercritical fluids, 3) analysis of thermoelectric modules, and 4) momentum, heat, mass and charge transport in the presence of apparent slip. Professor Hodes is the sole- or co-author of 50 papers in archival journals on these subjects. He is also a co-inventor on 15 issued US patents. His current research lies in three areas. First, analytical solutions for Poiseuille and Nusselt numbers for liquid flows over diabatic structured surfaces that capture, e.g., the effects of curvature, thermocapillary stress and/or evaporation and condensation along menisci, are being developed. This thread is in the context of the Red Lotus Project, a collaboration with applied mathematicians at Imperial College London. Secondly, a series of experiments to measure densities, molecular and Soret diffusion coefficients and mass transfer rates in alcohol-carbon dioxide solutions at supercritical conditions relevant to the drying of aerogels are being conducted. Thirdly, a numerical method for the optimization of heat sinks is under development. The latter was recently spun out of Tufts University as a software product by a start-up company, Transport Phenomena Technologies, LLC, co-founded by Professor Hodes, per NSF SBIR funding.
Host: AME Department
More Info: https://usc.zoom.us/j/94808927541
Location: Online event
WebCast Link: https://usc.zoom.us/j/94808927541
Audiences: Everyone Is Invited
Posted By: Tessa Yao