讲座人:雷成旺 副教授 悉尼大学
讲座时间:2016年1月21日星期四下午14:00
讲座地点:address
讲座内容:Natural and controlled transitions of natural convection boundary layers ABSTRACT In this talk, the characteristics of three-dimensional (3D) flow structures in natural convection boundary layers undergoing both natural and controlled transitions are described based on direct numerical simulations. Natural transition refers to the response of thermal boundary layers to random environmental disturbances, and controlled transition refers to the response of thermal boundary layers to particular modes of disturbances. Two modes of controlled transition including K-type and H-type transitions are presented. The K-type transition is triggered by resonant interaction between two-dimensional (2D) Tollmien-Schlichting (TS) waves and oblique waves of the same frequency, and the H-type transition is triggered by resonant interaction between 2D TS waves and oblique waves of half frequency of the TS waves. Spatially and temporally organised 3D structures are observed in all types of transitions. Under the natural transition, particular wavenumber and frequency perturbations survive in the 3D boundary layer. Aligned Ʌ-shaped vortices are observed in the K-type transition and staggered Ʌ-shaped vortices are observed in the H-type transition. The features of thermal boundary layer transition are generally similar to those reported for Blasius boundary layers. INFORMATION ABOUT THE SPEAKER Dr Chengwang Lei obtained his Bachelor and Master degrees in Mechanical Engineering at Huazhong University of Science & Technology in China and a PhD degree in Civil & Resource Engineering at The University of Western Australia. Since the completion of his PhD degree he has held a number of research and academic positions across multiple disciplines and at different institutions. Presently, he is an Associate Professor of Fluid Engineering in the School of Civil Engineering, The University of Sydney, Australia. Dr Lei’s research has been focused mainly on buoyancy driven flows related to energy and water with environmental and industrial applications. His research interest spans over experimental modelling, numerical simulation and analytical investigation of a range of fluid and thermal engineering problems. Much of his research has been supported by the Australian Research Council’s Discovery Projects grants. To date Dr Lei has published over 80 refereed articles in international journals and 60+ refereed articles in national and international conference proceedings.
讲座时间:2016年1月21日星期四下午14:00
讲座地点:address
讲座内容:Natural and controlled transitions of natural convection boundary layers ABSTRACT In this talk, the characteristics of three-dimensional (3D) flow structures in natural convection boundary layers undergoing both natural and controlled transitions are described based on direct numerical simulations. Natural transition refers to the response of thermal boundary layers to random environmental disturbances, and controlled transition refers to the response of thermal boundary layers to particular modes of disturbances. Two modes of controlled transition including K-type and H-type transitions are presented. The K-type transition is triggered by resonant interaction between two-dimensional (2D) Tollmien-Schlichting (TS) waves and oblique waves of the same frequency, and the H-type transition is triggered by resonant interaction between 2D TS waves and oblique waves of half frequency of the TS waves. Spatially and temporally organised 3D structures are observed in all types of transitions. Under the natural transition, particular wavenumber and frequency perturbations survive in the 3D boundary layer. Aligned Ʌ-shaped vortices are observed in the K-type transition and staggered Ʌ-shaped vortices are observed in the H-type transition. The features of thermal boundary layer transition are generally similar to those reported for Blasius boundary layers. INFORMATION ABOUT THE SPEAKER Dr Chengwang Lei obtained his Bachelor and Master degrees in Mechanical Engineering at Huazhong University of Science & Technology in China and a PhD degree in Civil & Resource Engineering at The University of Western Australia. Since the completion of his PhD degree he has held a number of research and academic positions across multiple disciplines and at different institutions. Presently, he is an Associate Professor of Fluid Engineering in the School of Civil Engineering, The University of Sydney, Australia. Dr Lei’s research has been focused mainly on buoyancy driven flows related to energy and water with environmental and industrial applications. His research interest spans over experimental modelling, numerical simulation and analytical investigation of a range of fluid and thermal engineering problems. Much of his research has been supported by the Australian Research Council’s Discovery Projects grants. To date Dr Lei has published over 80 refereed articles in international journals and 60+ refereed articles in national and international conference proceedings.