Report title: Foam flow phenomena and mechanism of ships
Speaker: Prof. Wan Decheng (Shanghai Jiaotong University)
Address: 412, Taishan Scientific Research Building
Report time: 08:40-10:10, June 23, 2021
Abstract: In the actual Marine environment, a large area of white foam flow can occur when a sailing vessel interacts with the surrounding fluid.The foam flow of ships involves complex hydromechanics mechanisms such as multiphase flow, multiscale flow, multifactor flow, violent flow and motion boundary.In the phenomenon of ship foam flow, there is a large number of gas entrainment below the water surface and then evolve into multi-scale bubbles, while there is a large range of liquid splashing above the water surface and then form atomized droplets. Meanwhile, bubbles and droplets are coupled with turbulence near the large deformation free surface, and multiphase mixing occurs.The foam flow phenomenon of ships has four characteristics :(1) the maintenance characteristics of underwater bubbles.The bubbles in the foam flow have complex oscillations near the free surface, and the bubbles with high surface energy can maintain a very long time after contact with the free surface.(2) Maintenance characteristics of airborne droplets.The evolution of foam flow in the air involves the coupling effect of wind, wave and flow, which leads to the diffusion evolution of violent pulsation.(3) Repeated transformation characteristics of water-air-bubble-fog.The internal evolution of foam flow is highly unsteady, and bubbles and droplets will produce multiple flow states in the process of free surface interaction.(4) Time-space multi-scale characteristics with very large span.In this report, the phenomena of foam flow on ships are analyzed, and the key and complex problems such as gas core, infiltration, mixing, impact, breakage, coalescence and transformation are discussed and considered.
Expert Profile:
Wan Decheng, Director of Computational Hydrodynamics Research Center of Ship and Ocean Engineering (CMHL), Shanghai Jiao Tong University, Chief Scientist of National Key RESEARCH and Development Program, Shanghai Outstanding Academic Leader, New Century Outstanding Talent of Ministry of Education, Shanghai Pujiang Talent program, Adjunct Professor of University of Strathclyde, UK, Adjunct Professor of Zhejiang University,Adjunct Professor, Dalian University of Technology.
Professor de-cheng wan is mainly engaged in ship and ocean engineering hydrodynamics, the complex flow field CAE software, independent research and development of high performance parallel computing technology, based on CFD hydrodynamic configuration and machine learning and Marine structure optimization, big data and in-depth study of ship's comprehensive performance forecast, Marine extreme sea conditions and load, Marine logistics fluid-solid coupling structure, a new concept of Marine structures,Research on the performance of offshore new energy development device.Independently developed naoe-Foam-SJTU and MLParticle-SJTU software for hydrodynamic simulation of ship and ocean engineering, etc., obtained more than 30 software Copyrights and published more than 530 papers.He has made many original achievements in computational fluid dynamics methods of Marine and offshore engineering, numerical solution methods of fluid-structure interaction, and software development of high performance computing and numerical pools.In 2020, he was selected as one of the world's top 2% scientists in the field of civil engineering (the only scholar from Mainland China selected in the field of Marine engineering). In 2018, 2019 and 2020, he was selected as the World's Highly cited Chinese Scholar in the field of Marine Engineering by Elsevier.2020 CH Kim Award, 2020 ISOPE AwardInternational Moan-Faltinsen Award for Best Paper in 2020, the 4th Excellent Scientific Paper Award of China Association for Science and Technology in 2019 (the only paper awarded in the field of ocean Engineering in 2019), etc.
Currently, he is a member of the Executive Committee of the International Offshore and Polar Engineering Society (ISOPE) (the first time for a Chinese mainland scholar), chairman of the ISOPE Hydrodynamics Committee, member of the ISOPE Technical Committee (TPC), and advisory Board member of the International Ship Model Towing Tank Conference (ITTC).Member of steering Committee of International Ship CFD Conference (the first time for Chinese scholars around the world), Standing Director of Global Chinese Society of Computational Mechanics, Member of International Advisory Committee of Ocean Systems Engineering department of KAIST University of Korea, Member of Ship Mechanics Academic Committee of Chinese Society of Naval Architects, Member of Professional Committee of Ocean Society of China,Member of the New Numerical Method and Application Professional Group, Computational Mechanics Professional Committee, Chinese Society of Mechanics, Chairman of the Executive Committee of The National Ship and Ocean Engineering CFD Conference, Deputy Director of the Design Professional Academic Committee of Shanghai Society of Ship and Ocean Engineering, Vice President of Shanghai Western Returned Scholars Association In Britain Branch,Editorial board member of 8 international journals such as Ocean Engineering and Applied Ocean Research, deputy editor, executive board member or editorial board member of 10 domestic journals such as Journal of Hydrodynamics and Ocean Engineering.