A random walk simulation of scalar mixing in flows through submerged vegetations  

作　　者：梁东方 WU Xuefei 

机构地区：[1]MOE Key Laboratory of Hydrodynamics, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University [2]Department of Engineering, University of Cambridge

出　　处：《Journal of Hydrodynamics》2014年第3期343-350,共8页水动力学研究与进展B辑（英文版）

基　　金：supported by the Non-profit Industry Financial Program of the Ministry of Water Resources (Grant No. 201401027);the China Scholarship Council

摘　　要：The scalar transport phenomena in vertical two-dimensional flows are studied using the random walk method. The established Lagrangian model is first applied to study the idealized longitudinal dispersion in open channels, before being used to investigate the scalar mixing characteristics of the flows through submerged vegetations. The longitudinal dispersion coefficients of the fully-developed boundary layer flows, with and without vegetations, are calculated based on the positions of the particles. A convenient way of incorporating the effects of vegetations is proposed, where all the flow parameters are regarded to be continually distributed over the depth. The simulation results show high accuracy of the developed random walk method, and indicate that the new method of accounting for the vegetation effects is appropriate for all the test cases considered. The predicted longitudinal dispersion coefficients agree well with the measurements. The merit of the new method is highlighted by its simplicity and efficiency in comparison with the conventional method that assumes the discontinuous distribution of the flow parameters over the depth.The scalar transport phenomena in vertical two-dimensional flows are studied using the random walk method. The established Lagrangian model is first applied to study the idealized longitudinal dispersion in open channels, before being used to investigate the scalar mixing characteristics of the flows through submerged vegetations. The longitudinal dispersion coefficients of the fully-developed boundary layer flows, with and without vegetations, are calculated based on the positions of the particles. A convenient way of incorporating the effects of vegetations is proposed, where all the flow parameters are regarded to be continually distributed over the depth. The simulation results show high accuracy of the developed random walk method, and indicate that the new method of accounting for the vegetation effects is appropriate for all the test cases considered. The predicted longitudinal dispersion coefficients agree well with the measurements. The merit of the new method is highlighted by its simplicity and efficiency in comparison with the conventional method that assumes the discontinuous distribution of the flow parameters over the depth.

关 键 词：random walk longitudinal dispersion submerged vegetations scalar mixing 

分 类 号：O35[理学—流体力学]