水科学进展2016，Vol.27Issue(2)：249-255,7.DOI:10.14042/j.cnki.32.1309.2016.02.010
基于单颗粒受力的均匀推移质颗粒对流和扩散特征
Advection and diffusion characteristics for uniform bed load particles from a semi-mechanistic model accounting for forces exerted on individual particles
摘要
Abstract
An episodic Langevin equation, which could account for forces exerted on individual particles and simulate stochastic and episodic motion characteristics of particles, is developed in order to reveal the control factor of normal or anomalous advection and diffusion characteristics for uniform particles. Using a model embedded with different dis-tributed resting times, we study advection and diffusion characteristics by analyzing the statistical data of a large num-ber of simulated particle trajectories. The results reveal that for uniform particles, because of the constraint of thin-tailed velocities of active particles, super-diffusion does not necessarily occur, even if their step lengths are heavy tailed. Diffusion characteristics are determined by the tail of resting times; for heavy-tailed resting times, sub-, nor-mal, and super diffusion could all occur. The proposed semi-mechanistic model is further compared with other stochas-tic models, and the step time is ignored as it could result in right advection but wrong diffusion characteristics, which could be generalized for studying stochastic variables, i. e., the higher the moment of the studied stochastic variables, the more complex the model.关键词
推移质/郎之万方程/对流/扩散/长尾/窄尾/正常/反常Key words
bed load/Langevin-equation/diffusion/advection/normal/anomalous/thin/heavy tailed分类
建筑与水利引用本文复制引用
范念念,聂锐华,杨克君,刘兴年,陈日东..基于单颗粒受力的均匀推移质颗粒对流和扩散特征[J].水科学进展,2016,27(2):249-255,7.基金项目
国家自然科学基金资助项目（51509172；51539007） The study is financially supported by the National Natural Science Foundation of China （ No．51509172；No．51539007）． （）
