Speaker: Metin Muradoglu, Department of Mechanical Engineering, Koc University, Istanbul
2 November 2011,13:40 pm (FENS L027)
Title: Computational Modeling of Interfacial Flows with Soluble Surfactants
Abstract: Surface active agents (surfactants) are either present as impurities that are difficult to remove from a system or they are deliberately added to fluid mixtures to manipulate interfacial flows. Surfactant molecules typically consist of a hydrophilic head and a hydrophobic tail—detergents are common examples. They are collected at the fluid interfaces forming a buffer zone between the continuous fluid and the drop fluid molecules, and thus decrease the interfacial tension. Non-uniform surfactant concentration leads to non-uniform normal (capillary) and tangential (Marangoni) stresses which can significantly affect the motion and deformation of drops and bubbles. Surfactants are widely used in numerous important scientific/engineering applications and natural processes. In particular, surfactant plays a vital role in respiration system by reducing the work required to expand lungs.
Direct simulation of interfacial flows with soluble surfactant is notoriously difficult task. Surfactants are advected and diffused both at the interface and in the bulk fluid by the motion of fluid and by molecular mechanism, respectively. Therefore the evolution equations of the surfactant concentrations at the interface and in the bulk fluid must be solved coupled with the flow equations. The surfactant concentration at the interface alters the interfacial tension and thus alters the flow field in a complicated way. This interaction between the surfactant and the flow field is highly non-linear and poses a computational challenge. In this talk, I’ll describe a front-tracking method developed for direct simulation of interfacial flows with soluble surfactant. I’ll also present sample simulation results that demonstrate the ability of the method for accurate modeling of interfacial flows with soluble surfactant.
Dr. Muradoglu is an associate professor of Mechanical Engineering at Koc University. He received BS degree from Istanbul Technical University (ITU) in Aeronautical Engineering in 1992, and MS and PhD degrees both from Cornell University in 1997 and in 2000, respectively. He then worked as a postdoctoral research associate at Cornell for about two years before joining to Koc University faculty in 2001 as an assistant professor. He specializes in computational fluid dynamics (CFD). His recent research interests include computational modeling of interfacial flows encountered or inspired by bio/microfluidic applications and turbulent combustion. Dr. Muradoglu is recipient of several awards including TUBA-GEBIP, TUBITAK encouragement, METU Mustafa Parlar Foundation encouragement and Fevzi Akkaya Foundation (FABED) young investigator awards.