报告题目：SPH and EBG Coupled Modeling of Fluid-fiber Interactions
Moubin Liu, Professor at the Peking University. He got his Bachelor, Master and PhD from Xi’an Jiaotong University and the National University of Singapore respectively, and worked at the National University of Singapore, Idaho National Laboratory, Nanyang Technological University and Chinese Academy of Sciences before he joined Peking University in 2014.
His areas of interests include computational mechanics, fluid structure interaction and multi-scale modeling.He published two popular monographs and some 90 journal publications with more than 4000 citations.He is in the editorial board of 8 national and international journals and serves as the standing member of the scientific committee for a number of international conferences including ICCP, ICCM and ICMMES. He delivered more than 50 invited lectures in academic conferences including 8 Plenary Lectures since 2008. He has been listed as the Most Cited Chinese Researchers by Elsevier and has got a number of prestigious awards including the Fellow Award in 2016 by the International Chinese Association of Computational Mechanics, 100 Talent Scholar in 2010 from the Chinese Academy of Sciences, Young Investigator Award in 2007 from the Asia-Pacific Association of Computational Mechanics and Lee Kuan Yew Fellow Award in 2005 from the Singapore Lee Kuan Yew Foundation.
The dynamics of a flexible object in a fluid is fundamentally important in engineering and sciences.Numerical simulation of flexible fibers interacting with fluid flows is usually a great challenge for conventional grid-based numerical methods, as the fluid-flexible fiber interaction involves moving interfaces and deformable boundaries. In this talk, smoothed particle hydrodynamics (SPH)  and element bending group (EBG) are coupled for modeling the interaction of viscous fluid with flexible structures with large deformation. SPH particles are used to model the viscous fluid flow governed by Navier-Stokes equations, and EBG particles are used to model the dynamic movement and deformation of flexible objects (such as fibers). The interaction of the neighboring fluid (SPH) and solid (EBG) particles renders the interaction of fluid and flexible structure.
The SPH-EBG coupling approach is validated by a number of numerical examples and then applied to model the interaction of a flexible fiber with viscous fluid. In numerical simulation, flexible fibers of different lengths are immersed in a moving viscous fluid driven by a body force. The drag force on the fiber obtained from SPH-EBG simulation agrees well with experimental observations. It is shown that the flexible fiber demonstrates four typical bending modes, including the U-shaped mode, the slight swing mode, the violent flapping mode, and the closed mode. The flexible fiber experiences a drag reduction due to its reconfiguration by bending. It is also found that the U4/3 drag scaling law for a flexible fiber is only valid for the U-shaped mode, but not valid for the flapping and closed modes. The results indicate that the reconfiguration of a flexible fiber is caused by the fluid force acting on it, while vortex shedding is of importance in the transition of bending modes. It is also shown that there exists a transition criterion for the flexible fiber from the swing mode to the flapping mode. Two non-dimensional parameters for characterizing a fiber-fluid interaction system are given and these two parameters are revealed to be inherently co-related.