Analytical Solution for Bichromatic Waves on Linearly Varying Currents
Abstract
:1. Introduction
2. Formulations and Methods
2.1. Boundary Value Problem
2.2. Perturbation Method
3. Analytical Solutions for Bichromatic Waves on Linear Shear Currents
3.1. Zeroth-Order Problem
3.2. First-Order Problem
3.3. Second-Order Problem
3.4. Third-Order Problem
3.5. Velocity of Water Particles and Pressure Field
3.6. Example of Bichromatic Wave on Vertically Linear Shear Current
4. The Nonlinear Dispersion Relation for Bichromatic Interactions on Linear Shear Currents
4.1. Singularity of Solving for Wavenumbers with the Nonlinear Dispersion Relation
4.2. Influence of the Shear Current on Wavelength
5. Influence of Shear Current Velocities and Vorticities on Bound Long Waves
6. Concluding Remarks
- The nonlinear dispersion relation, which is derived while solving for the third-order components, shows the amplitude dispersion (see Equation (53)). For bichromatic waves on linear shear currents, it can be seen that the amplitude dispersion of the two wave trains involves the effects of the amplitude on each other.
- A bichromatic wave example is illustrated, where the first-order and the third-order solutions are compared in terms of both surface elevation and their velocity profiles. In the example, a significant difference is found in the wavelength. Moreover, it is seen that in the discussed case, the first-order solution overestimates the maximum velocity, especially near the free surface.
- Wavenumbers may not always be found in the framework of proposed approach. They can only be found at the points of intersection of the two dispersion relations, and if the points are near the singularity, the solution cannot be obtained, either. For the discussed case, a group of wavenumbers with opposite directions can be obtained when and , but no solutions are found when and .
- From the discussed cases, it is found that as the vorticity of the current increases, both the wavelength and the maximum horizontal particle velocity increase. It is also found that the increase is more prominent for a shorter wave component.
- The intensities of the bound long waves are also discussed. It is found that for the second-order sub-harmonic bound long wave (), the intensity increases as the current velocity increases, whereas for the third-order sub-harmonic bound long wave () the intensity decreases as the current velocity increases. When the current velocity at the mid-depth is between −0.35 and 0.35 m/s, for both the second- and the third-order bound long waves, the intensity is found to increase as the vorticity increases, regardless of whether the current is following or opposing. However, when a stronger opposing current occurs (i.e. ), the intensity of the third-order bound long wave as a function of vorticity is found to be non-monotonic. A minimum is found at about , with a value of .
- For primary wave trains in the opposite directions, the bound long wave can still be illustrated as functions of current velocity or vorticity. In the discussed cases, as the current velocity increases, increases, but decreases for all of the discussed vorticities. However, and are shown to be non-monotonic as the current velocity increases. Furthermore, for both positive and negative current velocities, as the vorticity increases, increases, but decreases. For the positive current velocity case, as the vorticity increases, increases, and decreases, and for the negative current velocity case, the result is the opposite.
- The derived solutions have only been verified with the theories from previous researches which are the special cases of this study. Therefore, it is suggested that a set of numerical simulations or laboratory experiments of bichromatic waves on shear currents are desired to further compare the findings in the present study.
Author Contributions
Funding
Conflicts of Interest
References
- Hwung, H.-H.; Lin, Y.H.; Hsiao, S.-C. The Experimental Study on Infra-gravity Wave. Ocean. Eng. 2007, 34, 1481–1495. [Google Scholar] [CrossRef]
- Masselink, G. Group Bound Long Waves as a Source of Infragravity Energy in the Surf Zone. Cont. Shelf. Res. 1995, 15, 1525–1547. [Google Scholar] [CrossRef]
- Ruessink, B.G. Bound and Free Infragravity Waves in the Nearshore Zone under Breaking, Nonbreaking Conditions. J. Geophys. Res. Ocean. 1998, 103, 12795–12805. [Google Scholar] [CrossRef]
- Dalrymple, R.A.; Dean, R.G. Waves of Maximum Height on Uniform Currents. J. Waterw. Harb. Coast. Eng. Div. 1975, 101, 259–268. [Google Scholar] [CrossRef]
- Chen, Y.Y.; Juang, W.J. Primary Analysis on Wave-Current Interaction. In Proceedings of the 12th Conference on Ocean Engineering, Taichung City, Taiwan, 23–24 November 1990; pp. 248–265. [Google Scholar]
- Tsao, S. Behavior of Surface Waves on a Linearly Varying Current. Moskov. Fiz. Technol. Inst. Issted. Mekh. Prikl. Mat. 1959, 3, 66–84. [Google Scholar]
- Kishida, N.; Sobey, R.J. Stokes Theory for Waves on Linear Shear Current. J. Eng. Mech 1988, 114, 1317–1334. [Google Scholar] [CrossRef]
- Sharma, J.N.; Dean, R.G. Second-Order Directional Seas and Associated Wave Forces. Soc. Pet. Eng. J. 1981, 21, 129–140. [Google Scholar] [CrossRef]
- Madsen, P.A.; Fuhrman, D.R. Third-order theory for bichromatic bi-directional water waves. J. Fluid Mech 2006, 557, 369–397. [Google Scholar] [CrossRef]
- Dingemans, M.W. Water Wave Propagation over Uneven Bottoms: Linear Wave Propagation; World Scientific: Singapore, 1997. [Google Scholar]
Third-Order Solutions | |||||
---|---|---|---|---|---|
Wave Properties | Surface Elevation | Stream Function | |||
2.0740 | 0.6175 | 0.7038 | |||
1.7019 | 0.4792 | 2.0242 | |||
0.0683 | 0.5563 | 0.0060 | |||
−0.0093 | −0.1681 | 0.0418 | |||
0.4963 | 0.2740 | 0.0165 | |||
0.3319 | 0.1526 | −2.6118 | |||
0.7014 | −0.0000 | ||||
−7.0698 | 0.0002 | ||||
0.5791 | −0.0001 | ||||
0.1160 | 1.9642 | ||||
0.1105 | −0.0002 | ||||
−0.0166 | −0.6598 |
First-Order Solutions | |||||
---|---|---|---|---|---|
Wave Properties | Stream Function | ||||
2.2002 | 0.5215 | 0.6254 | |||
1.6868 | 0.3297 | 2.0437 |
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Lee, M.-J.; Hsiao, S.-C. Analytical Solution for Bichromatic Waves on Linearly Varying Currents. Mathematics 2022, 10, 1666. https://doi.org/10.3390/math10101666
Lee M-J, Hsiao S-C. Analytical Solution for Bichromatic Waves on Linearly Varying Currents. Mathematics. 2022; 10(10):1666. https://doi.org/10.3390/math10101666
Chicago/Turabian StyleLee, Mu-Jung, and Shih-Chun Hsiao. 2022. "Analytical Solution for Bichromatic Waves on Linearly Varying Currents" Mathematics 10, no. 10: 1666. https://doi.org/10.3390/math10101666