Turbulence on the Liquid-gas Interface and Wave Breaking

液-气界面上的湍流和波浪破碎

• 批准号: 08455473
• 负责人: MORI Kazu-hiro
• 金额: $ 3.39万
• 依托单位: HIROSHIMA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08455473/
• 关键词: liquid-gas interface; turbulence; wave breaking; sub breaking wave; vortical flow; LES; sub-breaking; 不安定; 乱流; 波面曲率; 渦; 自由表面境界層

The understanding of wave breaking phenomena on liquid-gas interface is important not only academically but practically for the design of ships or ocean structures. However, the breaking phenomena have not been made completely clear in spite of quite a few experimental and numerical studies.A careful observation discloses that instability or turbulence appears in the free-surface flow at a certain uniform velocity which is lower than that the overturning takes place. The apperance is quite sudden and similar to the commonly acknowledged turbulence transition of the boundary layr flows. The instability or the turbulence seems to play an important role in free-surface breaking phenomena.Characteristics of sub-breaking waves are studied by numerical simulations. Because the sub-breaking waves are the waves with fluctuating or turbulent-like free-surface flows, the numerical schemes must capture the turbulent characteristics. Here the Large Eddy Simulation with sub-grid model is used for the related region and the Reynolds averaged equation with Baldwin Lomax model is used for other region. The scheme handles the fully nonlinear free-surface boundary conditions including the tangential component. This is because the tangential free-surface boundary condition becomes relatively important when the free-surface curvature is large as common in breaking wave problems. Through the ismulated results discussions are made on the appearance condition of the sub-breaking waves.

气液界面上波浪破碎现象的研究对船舶和海洋结构物的设计具有重要的理论和实际意义。然而，尽管已有大量的实验和数值研究，但对这种破碎现象的认识还不十分清楚，仔细观察发现，在低于倾覆速度的一定匀速下，自由表面流动会出现不稳定或湍流。这一现象十分突然，类似于一般公认的边界层湍流转捩。不稳定性或湍流在自由面破碎现象中起着重要的作用，通过数值模拟研究了亚破碎波的特征。由于亚破碎波是具有波动或类似于粘性的自由表面流动的波，因此数值格式必须捕捉湍流特性。本文对相关区域采用亚网格模型的大涡模拟，对其它区域采用Baldwin-Lomax模型的雷诺平均方程。该方案处理完全非线性自由表面边界条件，包括切向分量。这是因为当自由面曲率较大时，切向自由面边界条件变得相对重要，这在破碎波问题中是常见的。通过模拟结果对亚破波的出现条件进行了讨论。

项目成果

Yasuaki Doi: "Vorticity Generation on the Curved Free Surface around Bow." Proceedings of CFD Symp for Free-Surface Flows. 43-52 (1996)

Yasuaki Doi：“弓周围弯曲自由表面上产生涡量。”

K.Mori: "Turbulent Flow Simulation of Sub-Breaking Wave" Proceeding of the 1997 ASME Fluids Engineering Division. FEDSM97-3392 (1997)

K.Mori：“亚破浪的湍流模拟”1997 年 ASME 流体工程部论文集。

U.C.Jeong: "Turbulence on the Free Surface around Bow" Second Workshop on Hull Form Design & Flow Phenomena. 193-209 (1996)

U.C.Jeong：“船首周围自由表面上的湍流”第二期船体形状设计研讨会

K.Mori: "Turbulent Flow Simulation of Sub Breaking Wave" Proc.of the 1997 ASME Fluids Engineering Division. FEDSM97-3392 (1997)

K.Mori：“亚破碎波的湍流模拟”Proc. of 1997 ASME 流体工程部。

U-C.Jeong: "Numerical Study of Separated Flows on the Free Surface around Struts" The Third Korea-Japan Joint Workshop on Ship and Marin Hydrodynamics. 301-308 (1996)

U-C.Jeong：“支柱周围自由表面分离流的数值研究”第三届韩日船舶与海洋流体动力学联合研讨会。