Effect of porosity on an internal solitary wave propagating over a porous trapezoidal obstacle

Ming Hung Cheng, Chih Min Hsieh, John R C Hsu, Robert R. Hwang

    Research output: Contribution to journalArticle

    1 Citation (Scopus)

    Abstract

    A permeable seabed may influence the evolution of an internal solitary wave propagating on a continental shelf and nearshore. In order to study the porous effect, numerical simulations are performed to investigate the flow field and waveform inversion of a large depression ISW propagating over a porous trapezoidal obstacle. A finite volume based Cartesian grid method is adopted to solve the Reynolds averaged Navier-Stokes equations using a k-ε model for the turbulent closure and porous media model together. Numerical results reveal that waveform inversion weakens significantly, as the porosity of the obstacle increases, except when porosity nf<0.2. At the same time, the magnitude of vorticity and turbulent energy decrease remarkably due to acute reduction of the production term induced by percolation and wave-pore interaction. Moreover, a skewed hump shaped relation appears between the maximum vorticity and the porosity. For transmitted wave energy on a horizontal plateau, total energy may decrease as nf<0.2 but increases moderately while nf>0.2 during a strong wave-obstacle interaction.

    Original languageEnglish
    Pages (from-to)126-141
    Number of pages16
    JournalOcean Engineering
    Volume130
    DOIs
    Publication statusPublished - 15 Jan 2017

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    Solitons
    Porosity
    Navier Stokes equations
    Porous materials
    Flow fields
    Computer simulation

    Cite this

    Cheng, Ming Hung ; Hsieh, Chih Min ; Hsu, John R C ; Hwang, Robert R. / Effect of porosity on an internal solitary wave propagating over a porous trapezoidal obstacle. In: Ocean Engineering. 2017 ; Vol. 130. pp. 126-141.
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    abstract = "A permeable seabed may influence the evolution of an internal solitary wave propagating on a continental shelf and nearshore. In order to study the porous effect, numerical simulations are performed to investigate the flow field and waveform inversion of a large depression ISW propagating over a porous trapezoidal obstacle. A finite volume based Cartesian grid method is adopted to solve the Reynolds averaged Navier-Stokes equations using a k-ε model for the turbulent closure and porous media model together. Numerical results reveal that waveform inversion weakens significantly, as the porosity of the obstacle increases, except when porosity nf<0.2. At the same time, the magnitude of vorticity and turbulent energy decrease remarkably due to acute reduction of the production term induced by percolation and wave-pore interaction. Moreover, a skewed hump shaped relation appears between the maximum vorticity and the porosity. For transmitted wave energy on a horizontal plateau, total energy may decrease as nf<0.2 but increases moderately while nf>0.2 during a strong wave-obstacle interaction.",
    keywords = "Internal solitary wave, k-ε turbulent model, Permeable obstacle, RANS equation",
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    Effect of porosity on an internal solitary wave propagating over a porous trapezoidal obstacle. / Cheng, Ming Hung; Hsieh, Chih Min; Hsu, John R C; Hwang, Robert R.

    In: Ocean Engineering, Vol. 130, 15.01.2017, p. 126-141.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - Effect of porosity on an internal solitary wave propagating over a porous trapezoidal obstacle

    AU - Cheng, Ming Hung

    AU - Hsieh, Chih Min

    AU - Hsu, John R C

    AU - Hwang, Robert R.

    PY - 2017/1/15

    Y1 - 2017/1/15

    N2 - A permeable seabed may influence the evolution of an internal solitary wave propagating on a continental shelf and nearshore. In order to study the porous effect, numerical simulations are performed to investigate the flow field and waveform inversion of a large depression ISW propagating over a porous trapezoidal obstacle. A finite volume based Cartesian grid method is adopted to solve the Reynolds averaged Navier-Stokes equations using a k-ε model for the turbulent closure and porous media model together. Numerical results reveal that waveform inversion weakens significantly, as the porosity of the obstacle increases, except when porosity nf<0.2. At the same time, the magnitude of vorticity and turbulent energy decrease remarkably due to acute reduction of the production term induced by percolation and wave-pore interaction. Moreover, a skewed hump shaped relation appears between the maximum vorticity and the porosity. For transmitted wave energy on a horizontal plateau, total energy may decrease as nf<0.2 but increases moderately while nf>0.2 during a strong wave-obstacle interaction.

    AB - A permeable seabed may influence the evolution of an internal solitary wave propagating on a continental shelf and nearshore. In order to study the porous effect, numerical simulations are performed to investigate the flow field and waveform inversion of a large depression ISW propagating over a porous trapezoidal obstacle. A finite volume based Cartesian grid method is adopted to solve the Reynolds averaged Navier-Stokes equations using a k-ε model for the turbulent closure and porous media model together. Numerical results reveal that waveform inversion weakens significantly, as the porosity of the obstacle increases, except when porosity nf<0.2. At the same time, the magnitude of vorticity and turbulent energy decrease remarkably due to acute reduction of the production term induced by percolation and wave-pore interaction. Moreover, a skewed hump shaped relation appears between the maximum vorticity and the porosity. For transmitted wave energy on a horizontal plateau, total energy may decrease as nf<0.2 but increases moderately while nf>0.2 during a strong wave-obstacle interaction.

    KW - Internal solitary wave

    KW - k-ε turbulent model

    KW - Permeable obstacle

    KW - RANS equation

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