非线性流函数在实验风浪场计算中的应用

doi:10.11978/2018039

Abstract

Abstract:

The wind on the water surface can create wind waves. The exchange mechanism of momentum and energy due to the turbulence of wave current is a complicated process. Wind stress is generally used to describe this energy exchange, and can be divided into three components: shear stress, wave induced stress and turbulent stress. An effective nonlinear wave current separation method, namely, the Nonlinear Stream Function Method (NSFM), is used to qualitatively describe the momentum and energy transports between wave and current. An analytical stream function is constructed, which can effectively express nonlinear waves and satisfies the Laplace equation, the boundary condition and the kinematic boundary condition of the water surface, separating the wave-induced velocity field based on the laboratory wind-wave data. Through the cross-spectral technique, the contribution of wave-induced Reynolds stress to wind stress at different wind speed is obtained. The results are as follows. NSFM has higher accuracy and better applicability in treating wind waves under different working conditions. With the increase of wind speed, wave-induced stress decays faster along water depth, and the ratio of wave-induced stress at the free surface to the momentum transport mechanism should be gradually weakened.

Key words: wind wave, wave-current separation, stream function

Changbo JIANG, Yang YANG, Hansong TANG. An application of nonlinear stream function in analysis of experimental wind-wave field[J].Journal of Tropical Oceanography, 2019, 38(1): 19-26.

Figures/Tables 10

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References 13

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序号	P/Hz	U_∞/(m·s^-1)	U_*/(m·s^-1)	H_1/3/cm	H_rms/cm	H_ave/cm	T/s	T_f/s	N	A_c-rms/cm	A_t-rms/cm
1	10	3.4	0.134	0.83	0.65	0.62	0.26	1.5	17	0.41	0.26
2	15	6.1	0.363	1.80	1.42	1.32	0.30	1.5	17	0.78	0.55
3	20	7.8	0.506	2.33	1.73	1.61	0.36	1.5	17	0.94	0.81
4	25	10.1	0.762	3.66	2.69	2.47	0.43	2	23	1.55	1.16
5	30	12.2	0.940	4.04	3.04	2.83	0.47	2	23	1.89	1.78
6	35	14.6	1.239	6.47	4.95	4.68	0.54	3	35	2.74	2.56

	动力边界条件	运动边界条件
全局误差	\({{E}_{1}}=\frac{1}{k}\sum\limits_{n=1}{k}{{{({{Q}_{\text{k}}}-\overset{\_}{\mathop{Q}}\,)}{2}}}\)	\({{E}_{2}}=\frac{1}{k}\sum\limits_{n=1}{k}{{{({{\eta }_{\text{pk}}}-{{\eta }_{\text{mk}}})}{\text{2}}}}\)
局部误差	\({{\delta }_{\text{1}}}\text{=}{{Q}_{\text{k}}}-\bar{Q}\)	\({{\delta }_{\text{2}}}={{\eta }_{\text{pk}}}-{{\eta }_{\text{mk}}}\)

An application of nonlinear stream function in analysis of experimental wind-wave field

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