バー型海岸における長周期波発達過程の数値解析  [in Japanese] NUMERICAL INVESTIGATIONS OF INFRAGRAVITY WAVE DEVELOPMENT ON A BARRED BEACH  [in Japanese]

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Abstract

沿岸砂州が形成されている平塚海岸で観測された長周期波発達過程のより詳細な理解を目的として,数値解析を用いた分析を行った.数値モデルとしては砕波判定に水面圧力勾配,砕波減衰にTVDによる数値粘性を適用した1次元強非線形ブシネスクモデルを開発し,実験・現地の観測結果と比較し良好な結果を得た.また,現地再現結果からは沿岸砂州頂部に腹節構造を持つ部分重複波の複雑な構造を確認した.さらに,長周期成分のエネルギー遷移過程の分析により,観測から示唆された段階的な長周期波発達が確認され,沿岸砂州付近では高次の非線形干渉が無視できないことを示唆する結果を得た.

 We constructed a 1-D Boussinesq model to reproduce previously observed infragravity waves developed on a barred beach on Hiratsuka Coast. We applied pressure gradient at sea surface for detection of wave-breaking and introduced numerical viscosity satisfying TVD condition to represent wave attenuation by wave-breaking. This model showed good agreements with both experiments and the observations. Modeled cross-shore distribution of wave spectra suggested development of long standing waves whose amplified frequency components had nodes/antinodes above the bar. We also confirmed gradual infragravity wave development which was inferred from the field observations.The model results suggested that 3<sup>rd</sup> order nonlinear interacton gives unignorable impacts on the development around the sand bar.

Journal

  • Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering)

    Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering) 74(2), I_19-I_24, 2018

    Japan Society of Civil Engineers

Codes

  • NII Article ID (NAID)
    130007504063
  • Text Lang
    JPN
  • ISSN
    1884-2399
  • Data Source
    J-STAGE 
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