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arXiv 2201.07390physics.flu-dyn
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表面张力降低对风浪成长及气-水标量输运的影响

Effects of surface tension reduction on wind-wave growth and air-water scalar transfer

Keigo Matsuda, Satoru Komori, Naohisa Takagaki, Ryo Onishi

AI总结:

本文通过气-水两相湍流直接数值模拟,研究了表面张力降低对风浪成长和界面标量输运的影响,发现表面张力降低会减少重力波向毛细波的能量传递,使有效波更快成长,同时抑制水侧湍流并降低标量输运系数。

摘要:

利用气-水两相湍流的直接数值模拟(DNS)研究了表面张力降低对风浪成长的影响。采用任意拉格朗日-欧拉方法配合贴体移动网格求解空气侧和水侧的不可压缩Navier-Stokes方程。在每秒数米的低风速条件下,对波长小于0.07 m的有限振幅、非破碎重力-毛细波在两种不同表面张力情形下的波浪成长进行了模拟。结果表明,较小表面张力情形下的有效波高比较小表面张力情形增长更快。重力波尺度和毛细波尺度的能量通量揭示,当表面张力降低时,从有效重力波向毛细波的能量传递减少,有效波从风中获得并积累更多能量。这导致较小表面张力情形下波浪成长更快。还研究了表面张力降低对气-水界面标量输运的影响。结果表明,水侧标量输运系数因表面张力降低而减小。该减小是由水侧湍流受到抑制所致。为支持这一推测,将表面张力效应与小型风浪水槽中的实验室实验进行了比较。

英文摘要:

Effect of surface tension reduction on wind-wave growth is investigated using direct numerical simulation (DNS) of air-water two-phase turbulent flow. The incompressible Navier-Stokes equations for air and water sides are solved using an arbitrary Lagrangian-Eulerian method with boundary-fitted moving grids. The wave growth of finite-amplitude and non-breaking gravity--capillary waves, whose wavelength is less than 0.07 m, is simulated for two cases of different surface tensions under a low--wind speed condition of several meters per second. The results show that significant wave height for the smaller surface tension case increases faster than that for the larger surface tension case. Energy fluxes for gravity and capillary wave scales reveal that, when the surface tension is reduced, the energy transfer from the significant gravity waves to capillary waves decreases and the significant waves accumulate more energy supplied by wind. This results in faster wave growth for the smaller surface tension case. Effect on the scalar transfer across the air-water interface is also investigated. The results show that the scalar transfer coefficient on the water side decreases due to the surface tension reduction. The decrease is caused by suppression of turbulence in the water side. In order to support the conjecture, the surface tension effect is compared with laboratory experiments in a small wind-wave tank.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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