Numerical hybrid grid for cnoidal wave generation and induced separated flow over a wavy bed

Chii-Jau Tang, Tzu Chiang Lee

Research output: Contribution to journalArticle

Abstract

A simple but effective hybrid grid method is proposed to solve a two-dimensional, multiscale, moving-boundary flow problem. Two unsteady flows of different length scales and degrees of boundary movability are involved in the numerical simulation: (1) the generation and propagation of cnoidal waves, and (2) the induced oscillatory boundary-layer flow over a ripple bottom. For wave generation by a given motion pattern of waveplate, the fully nonlinear, free-surface conditions are applied to get the flow solution in a moving boundary-fitted grid. The generated cnoidal wave is developed to its permanent form after five periods without introduction of a wave theory. On the other hand, under nonlinear wave motion, the thin oscillatory boundary layer with intermittent separation around the wavy solid boundary is resolved by a very fine and stationary grid. The unified hybrid grid enables the authors to carry out the detailed flow analysis and track particle trajectories in this study.

Original languageEnglish
Article number06014009
JournalJournal of Engineering Mechanics
Volume140
Issue number9
DOIs
Publication statusPublished - 2014 Sep 1

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Boundary layer flow
Unsteady flow
Boundary layers
Trajectories
Computer simulation

All Science Journal Classification (ASJC) codes

  • Mechanics of Materials
  • Mechanical Engineering

Cite this

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abstract = "A simple but effective hybrid grid method is proposed to solve a two-dimensional, multiscale, moving-boundary flow problem. Two unsteady flows of different length scales and degrees of boundary movability are involved in the numerical simulation: (1) the generation and propagation of cnoidal waves, and (2) the induced oscillatory boundary-layer flow over a ripple bottom. For wave generation by a given motion pattern of waveplate, the fully nonlinear, free-surface conditions are applied to get the flow solution in a moving boundary-fitted grid. The generated cnoidal wave is developed to its permanent form after five periods without introduction of a wave theory. On the other hand, under nonlinear wave motion, the thin oscillatory boundary layer with intermittent separation around the wavy solid boundary is resolved by a very fine and stationary grid. The unified hybrid grid enables the authors to carry out the detailed flow analysis and track particle trajectories in this study.",
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Numerical hybrid grid for cnoidal wave generation and induced separated flow over a wavy bed. / Tang, Chii-Jau; Lee, Tzu Chiang.

In: Journal of Engineering Mechanics, Vol. 140, No. 9, 06014009, 01.09.2014.

Research output: Contribution to journalArticle

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