Biography:Qi Li obtained her PhD from the department of civil and engineering in Princeton University this August. Her dissertation topic is on the intersection between boundary layer turbulence and the urban climate. Her research interests span a wide range of topics: from numerical methods, computational fluid dynamics and meteorology. During her graduate studies, she was a Geophysical Fluid Dynamics Fellow in the Woods Hole Oceanographic Institute; she also has won the best presentation award in the 9th International Conference on Urban Climate and the Wu Prize for Excellence from the Princeton School of Engineering and Applied Science. Qi works as a post-doc in the water center of Columbia University.

Abstract:Trees in urban environment is an indispensable part of urban sustainability. Realistically representing them in urban models is an ongoing area of research in urban environmental studies. This study develops a novel large-eddy simulation (LES) model that resolves buildings with enhanced wall-modeling approach and parameterizes urban trees by accounting their aerodynamic impact. The shading effect of trees are also explicitly taken into account by a subsurface conduction model coupled to LES. Two-dimensional street canyons with trees in the middle of the street is used a a prototype for case studies. It is found that under moderate canyon aspect ratio (height/width being 0.5 and 1) trees taller than the mean obstacle/building height leads to the strongest modification of the flow and temperature fields. Tall trees also alter the momentum and heat fluxes most significantly through direct interaction with the strong shear layer near the roof top. For high aspect ratio street canyons, the shading effect of trees, which produces the strongest modification of the surface energy, is the most important factor. The study overall highlights the importance of representing both the aerodynamic and thermodynamic changes due to trees in urban models.

讲座时间：2016.12.21 周三下午1点
讲座时间：资环楼271会议室