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Long-Wave and Integral Boundary Layer Analysis of Falling Film Flow on Walls With Three-Dimensional Periodic Structures

2010; Taylor & Francis; Volume: 32; Issue: 7-8 Linguagem: Inglês

10.1080/01457632.2010.509775

1521-0537

Tatiana Gambaryan‐Roisman, Hongyi Yu, Karsten Löffler, Peter Stephan,

Heat Transfer Mechanisms

Abstract Falling films exhibit very complex wavy patterns, which depend on the properties of the liquid, the Reynolds number, the wall inclination angle, and the distance from the film inlet. The film hydrodynamics governs the heat and mass transfer in the liquid films. Our vision is to control and enhance heat and mass transport by using walls with specific microscale topographies that influence the falling film flow, stability, and wavy pattern. In this work, long-wave theory and integral boundary layer approximation are used for modeling the falling film flow on walls with three-dimensional periodic microstructures. The wall topography is periodic both in the main flow direction and in the transverse direction. Examples of such microstructures are longitudinal grooves with sinusoidal path (or meandering grooves) and herringbone structures. The effects of the Reynolds number, the wall inclination angle, and the longitudinal and transverse periods of the structure on the shape of liquid–gas interface are investigated. It is shown that, as opposed to straight grooves in longitudinal direction, grooves with meandering paths may lead to significant interface deformations. Acknowledgments The authors acknowledge the support of the German Science Foundation, DFG, through the Emmy Noether Program and through the Collaborative Research Center 568. Tatiana Gambaryan-Roisman is a Privatdozent and a research group leader at the Institute for Technical Thermodynamics, Technische Universität Darmstadt, in Germany. In 1998 she earned her D.Sc. degree in mechanical engineering from Technion-Israel Institute of Technology, Haifa, Israel. From 1998 to 2000 she was a Minerva Research Fellow (Max Planck Society) at the Material Science Department of the University Erlangen-Nuremberg, Erlangen, Germany. Since 2000 she has been working at Technische Universität Darmstadt. In 2003 she founded an Emmy Noether-Junior Research Group "Evaporation of Thin Films on Structured Surfaces." In 2007 she founded together with colleagues a research center, "Center of Smart Interfaces." In 2008 she earned a Habilitation degree from the Faculty of Mechanical and Process Engineering, Technische Universität Darmstadt. Her research interests include heat and mass transfer, interfacial phenomena in liquids and solids, multiphase flows, phase change, hydrodynamic and thermal instabilities, micro- and nanoscale transport phenomena, and transport phenomena in porous media. Hongyi Yu is a Ph.D. student at Technische Universität Darmstadt in Germany. He studied mechanical engineering at Technische Universität Darmstadt and received his diploma in 2005. His doctoral research is focused on numerical simulation of wave development and heat transfer in thin falling films on structured plates. Karsten Löffler is a Ph.D. student in mechanical engineering at Technische Universität Darmstadt in Germany. He received his diploma in chemical engineering at Clausthal University of Technology and worked on heterogeneous reaction systems and simulation of pulverized coal combustion. His doctoral research at the Chair of Technical Thermodynamics is focused on the experimental investigation of falling liquid films on structured surfaces. Peter Stephan is professor and director of the Institute for Technical Thermodynamics at Technische Universität Darmstadt in Germany. He studied mechanical engineering at the Technical University of Munich. From 1989 to 1992 he was a Marie-Curie Research Fellow at the Joint Research Centre of the European Commission in Ispra, Italy. In 1992 he received his Ph.D. from the University of Stuttgart. From 1992 to 1997 he was working as a senior process engineer and research and development manager in the Mercedes-Benz group. Since 1997 he has been at Technische Universität Darmstadt. His main fields of research are phase change heat transfer and boiling, microscale heat and mass transfer, interfacial phenomena, heat pipe technology, and drying and freezing processes. Specific interests lie in multiscale approaches and the combination of numerical and experimental studies. From 2007 to 2009 he was the dean of the Mechanical Engineering Faculty. In 2007 he founded together with colleagues a new interdisciplinary research centre with a focus on smart fluid boundaries. He received the IIR Sadi Carnot Prize in 1995 and the SFT Prize for Excellence in Heat Transfer Research in 2002, and an ASME outstanding researcher award. He is president of the German Heat Transfer Association, editor-in-chief of the VDI Heat Atlas, and an editorial board member of Journal of Heat and Mass Transfer, Journal of Experimental Heat Transfer, and Journal of Experimental Thermal and Fluid Science.