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Inflows/outflows driven particle dynamics in an idealised lake

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journal contribution
posted on 01.05.2020, 09:20 by Cheng-hua Dang, Jingchun Wang, Qiuhua LiangQiuhua Liang
This paper considers fluid mixing driven by inflows connected to a circular shallow lake using a numerical framework consisting of a shallow water hydrodynamic model and a passive particle-tracking model. With the flow field driven by alternate inflows predicted by a shallow water model, particle trajectories are traced out using a particle tracking model. The horizontal fluid mixing dynamics are then interpreted using dynamics system analysis approaches including finite-time Lyapunov exponent (FTLE) and Lagrangian coherent structure (LCS). From the simulation results, it is confirmed that periodic inflows are able to create a weak dynamic system in an idealised circular lake, with the particle dynamics controlled by a single dimensionless parameter associated with the inflow duration. The mixing and transport property of the lake changes from regular to chaotic as the value of the dimensionless parameter increases until global chaotic particle dynamics is achieved. By further analysing the advection of particles injected continuously to the inflows (freshwater), the fate of “freshwater” particles in a “polluted” lake is tracked and revealed. The results provide useful guidance for engineering applications, i.e., transferring freshwater from rivers to improve the water quality in polluted water bodies such as lakes. The presented approach will be able to facilitate the design of ‘optimised’ schemes for such engineering implementation.

History

School

  • Architecture, Building and Civil Engineering

Published in

Journal of Hydrodynamics

Volume

31

Issue

5

Pages

873 - 886

Publisher

Springer

Version

AM (Accepted Manuscript)

Rights holder

© China Ship Scientific Research Center

Publisher statement

This is a post-peer-review, pre-copyedit version of an article published in Journal of Hydrodynamics. The final authenticated version is available online at: https://doi.org/10.1007/s42241-019-0070-9.

Acceptance date

26/05/2019

Publication date

2019-09-10

Copyright date

2019

ISSN

1001-6058

eISSN

1878-0342

Language

en

Depositor

Prof Qiuhua Liang. Deposit date: 30 April 2020