https://scholars.lib.ntu.edu.tw/handle/123456789/597984
標題: | Incorporating the Memory Effect of Turbulence Structures Into Suspended Sediment Transport Modeling | 作者: | Tsai C.W Huang S.-H Hung S.Y. WAN-SHAN TSAI |
關鍵字: | anomalous diffusion;non-Markovian process;random-walk based model;stochastic sediment transport;suspended sediment transport model;temporal correlation;Brownian movement;Diffusion in solids;Open channel flow;Sediment transport;Stochastic systems;Suspended sediments;Turbulence;Turbulent flow;Velocity control;Brownian motion process;Effective diffusion coefficients;Long term observations;Particle diffusion process;Probabilistic properties;Random walk modeling;Temporal correlations;Turbulence structures;Elementary particle sources;Brownian motion;modeling;open channel flow;persistence;sediment transport;stochasticity;suspended sediment;turbulence;turbulent flow | 公開日期: | 2021 | 卷: | 57 | 期: | 3 | 來源出版物: | Water Resources Research | 摘要: | Modeling of the random movement of fine sediment particles in open-channel turbulent flow is mostly built upon the memoryless Brownian motion process. Such a process describes the chaotic behavior of small particles without considering temporal correlations in terms of the particle moving velocity and direction (i.e., memory). However, when particles are transported in time-persistent turbulent flow, the movements of the suspended particles may exhibit persistency that depends on the various temporal durations of turbulent flow structures—such persistence results in direction and magnitude variations in the velocity of the fine moving particles. The diffusion property of the particles may then deviate from normal diffusion. The conventional memoryless random walk models may not provide a comprehensive description of the particle diffusion process for the duration of turbulence structures when the particles are subject to memory effects. In this study, a novel random walk model is proposed to present the temporal correlation of the suspended sediment particle velocity caused by turbulence structures in open channel flow. The probabilistic properties of the proposed model are discussed. In particular, enhanced physical insights are obtained regarding the particle diffusion behavior in turbulent flows. Numerical simulations are conducted to demonstrate that, similar to the conventional memoryless random walk models, the proposed model shows normal diffusion for long-term observations, despite its local superdiffusion behavior. The effective diffusion coefficient of the proposed stochastic process on a long-term time scale is formulated. ? 2021. American Geophysical Union. All Rights Reserved. |
URI: | https://www.scopus.com/inward/record.uri?eid=2-s2.0-85103236953&doi=10.1029%2f2020WR028475&partnerID=40&md5=8bcb65c17a0b6b822f5733678f3df97f https://scholars.lib.ntu.edu.tw/handle/123456789/597984 |
ISSN: | 00431397 | DOI: | 10.1029/2020WR028475 |
顯示於: | 土木工程學系 |
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