10 décembre 2020

Wébinaire Metin Muradoglu

Dr. Muradoglu is a professor of Mechanical Engineering at Koc University. He received his BS degree in Aeronautical Engineering from Istanbul Technical University (ITU) in 1992, and MS and PhD degrees both from Cornell University in 1997 and 2000, respectively. He also worked as a postdoc at Cornell for about 18 months before joining the Koc University faculty in 2001. He has had visiting positions at Harvard, Notre Dame and Princeton Universities, and the Max-Planck Institute for Intelligent Systems in Stuttgart. Dr. Muradoglu’s work has been recognized by multiple awards including the Turkish Academy of Sciences outstanding young scientist award (2009) and the Scientific and Technological Research Council of Turkey (TUBITAK) encouragement award (2010). He has been an associate member of Turkish Academy of Sciences since 2012.
Effects of viscoelasticity and surfactant on turbulent bubbly channel flows

Abstract: Interface-resolved direct numerical simulations are performed to examine the sole and combined effects of soluble surfactant and viscoelasticity on the structure of mon- and poly-dispersed bubbly turbulent channel flows for the friction Reynolds number in the rage between Reτ=127.3 and Reτ=250. A soluble surfactant and FENE-P viscoelastic models are coupled to the incompressible flow equations. In the clean case, small bubbles move toward the wall due to the inertial lift force, resulting in the formation of wall-layers and a significant reduction in the flow rate while larger bubbles tend to move toward channel center. An addition of strong enough surfactant alters the direction of lateral migration, i.e., the contaminated bubbles move toward the core region and spread out across the channel. For the viscoelastic case, shear-thinning effects and elastic forces promote formation of bubbly wall-layers leading to a strong decrease in the flow rate. Formation of a wall-layer is determined by the interplay of the inertial lift, elastic and Marangoni forces when they coexist.

10 décembre 2020, 16h3017h30
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28 mars 2024

Webinaire Rui Ni

The Wrath of the Small: Fragmentation of Bubbles in Turbulence by Small Eddies

Rui Ni est Assitant Professor en Engineering à l'Université Johns Hopkins (JHU) et a été nommé professeur DOE ORISE en 2019. Avant de rejoindre JHU, il était titulaire de la chaire Kenneth K. Kuo à la Penn State University. Il a obtenu son doctorat au département de physique de l'Université Chinoise de Hong Kong en 2011, et a travaillé comme chercheur postdoctoral à Yale et à l'Université Wesleyan. Il a reçu une bourse CAREER de la NSF dans le domaine de la dynamique des fluides, une bourse de jeune chercheur de l'ACS-PRF et une bourse Early Stage Investigation de la NASA. Ses recherches portent principalement sur le développement de méthodes expérimentales avancées pour comprendre les écoulements multiphasiques dans de nombreuses applications, telles que les systèmes énergétiques, les émulsions, l'ingestion de particules dans les turbines à gaz, les atterrissages sur des corps extraterrestres et l'atténuation des poussières pour les futures explorations spatiales.