Abstract
For surface gravity waves propagating over a horizontal bottom that consists of a patch of sinusoidal ripples, strong wave reflection occurs under the Bragg resonance condition. The critical wave frequency, at which the peak reflection coefficient is obtained, has been observed in both physical experiments and direct numerical simulations to be downshifted from the well-known theoretical prediction. It has long been speculated that the downshift may be attributed to higher-order rippled bottom and free-surface boundary effects, but the intrinsic mechanism remains unclear. By a regular perturbation analysis, we derive the theoretical solution of frequency downshift due to third-order nonlinear effects of both bottom and free-surface boundaries. It is found that the bottom nonlinearity plays the dominant role in frequency downshift while the free-surface nonlinearity actually causes frequency upshift. The frequency downshift/upshift has a quadratic dependence in the bottom/free-surface steepness. Polychromatic bottom leads to a larger frequency downshift relative to the monochromatic bottom. In addition, direct numerical simulations based on the high-order spectral method are conducted to validate the present theory. The theoretical solution of frequency downshift compares well with the numerical simulations and available experimental data.
Similar content being viewed by others
Change history
06 May 2022
An Erratum to this paper has been published: https://doi.org/10.1007/s13344-022-0029-4
References
Alam, M.R., Liu, Y.M. and Yue, D.K.P., 2010. Oblique sub- and super-harmonic Bragg resonance of surface waves by bottom ripples, Journal of Fluid Mechanics, 643, 437–447.
Chamberlain, P.G. and Porter, D., 1995. The modified mild-slope equation, Journal of Fluid Mechanics, 291, 393–407.
Chang, H.K. and Liou, J.C., 2007. Long wave reflection from submerged trapezoidal breakwaters, Ocean Engineering, 34(1), 185–191.
Dalrymple, R.A. and Kirby, J.T., 1986. Water waves over ripples, Journal of Waterway, Port, Coastal, and Ocean Engineering, 112(2), 309–319.
Davies, A.G., 1982. The reflection of wave energy by undulations on the seabed, Dynamics of Atmospheres and Oceans, 6(4), 207–232.
Davies, A.G. and Heathershaw, A.D., 1984. Surface-wave propagation over sinusoidally varying topography, Journal of Fluid Mechanics, 144, 419–443.
Dommermuth, D.G. and Yue, D.K.P., 1987. A high-order spectral method for the study of nonlinear gravity waves, Journal of Fluid Mechanics, 184, 267–288.
Fan, J., Zheng, J.H., Tao, A.F. and Liu, Y.M., 2021. Upstream-propagating waves induced by steady current over a rippled bottom: theory and experimental observation, Journal of Fluid Mechanics, 910, A49.
Fan, J., Zheng, J.H., Tao, A.F., Yu, H.F. and Wang, Y., 2016. Experimental study on upstream-advancing waves induced by currents, Journal of Coastal Research, 75, 846–850.
Guazzelli, E., Rey, V. and Belzons, M., 1992. Higher-order Bragg reflection of gravity surface waves by periodic beds, Journal of Fluid Mechanics, 245, 301–317.
Guo, F.C., Liu, H.W. and Pan, J.J., 2021. Phase downshift or upshift of Bragg resonance for water wave reflection by an array of cycloidal bars or trenches, Wave Motion, 106, 102794.
Liang, B.C., Ge, H.L., Zhang, L.B. and Liu, Y., 2020. Wave resonant scattering mechanism of sinusoidal seabed elucidated by Mathieu Instability theorem, Ocean Engineering, 218, 108238.
Liu, H.W., Li, X.F. and Lin, P.Z., 2019a. Analytical study of Bragg resonance by singly periodic sinusoidal ripples based on the modified mild-slope equation, Coastal Engineering, 150, 121–134.
Liu, H.W., Liu, Y. and Lin, P.Z., 2019b. Bloch band gap of shallow-water waves over infinite arrays of parabolic bars and rectified cosinoidal bars and Bragg resonance over finite arrays of bars, Ocean Engineering, 188, 106235.
Liu, H.W., Shi, Y.P. and Cao, D.Q., 2015. Optimization of parabolic bars for maximum Bragg resonant reflection of long waves, Journal of Hydrodynamics, 27(3), 373–382.
Liu, H.W., Zeng, H.D. and Huang, H.D., 2020. Bragg resonant reflection of surface waves from deep water to shallow water by a finite array of trapezoidal bars, Applied Ocean Research, 94, 101976.
Liu, W.J., Liu, Y.S. and Zhao, X.Z., 2019. Numerical study of Bragg reflection of regular water waves over fringing reefs based on a Boussinesq model, Ocean Engineering, 190, 106415.
Liu, Y.M. and Yue, D.K.P., 1998. On generalized Bragg scattering of surface waves by bottom ripples, Journal of Fluid Mechanics, 356, 297–326.
Mei, C.C., 1985. Resonant reflection of surface water waves by periodic sandbars, Journal of Fluid Mechanics, 152, 315–335.
Mei, C.C., Hara, T. and Naciri, M., 1988. Note on Bragg scattering of water waves by parallel bars on the seabed, Journal of Fluid Mechanics, 186, 147–162.
Miles, J.W., 1967. Surface-wave scattering matrix for a shelf, Journal of Fluid Mechanics, 28(4), 755–767.
Naciri, M. and Mei, C.C., 1988. Bragg scattering of water waves by a doubly periodic seabed, Journal of Fluid Mechanics, 192, 51–74.
O’Hare, T.J. and Davies, A.G., 1993. A comparison of two models for surface-wave propagation over rapidly varying topography, Applied Ocean Research, 15(1), 1–11.
Peng, J., Tao, A.F., Liu, Y.M., Zheng, J.H., Zhang, J.S. and Wang, R.S., 2019. A laboratory study of class III Bragg resonance of gravity surface waves by periodic beds, Physics of Fluids, 31(6), 067110.
Phillips, O.M., 1960. On the dynamics of unsteady gravity waves of finite amplitude. Part 1. The elementary interactions, Journal of Fluid Mechanics, 9(2), 193–217.
Qin, S.F., Fan, J., Zhang, H.M., Su, J.W. and Wang, Y., 2021. Flume experiments on energy conversion behavior for oscillating buoy devices interacting with different wave types, Journal of Marine Science and Engineering, 9(8), 852.
Short, A.D., 1975. Multiple offshore bars and standing waves, Journal of Geophysical Research, 80(27), 3838–3840.
Tao, A.F., Yan, J., Wang, Y., Zheng, J.H., Fan, J. and Qin, C., 2017. Wave power focusing due to the Bragg resonance, China Ocean Engineering, 31(4), 458–465.
Tao, A.F., **e, S.Y., Wu, D., Fan, J. and Yang, Y.N., 2021. The effects on water particle velocity of wave peaks induced by nonlinearity under different time scales, Journal of Marine Science and Engineering, 9(7), 748.
Tsai, L.H., Kuo, Y.S., Lan, Y.J., Hsu, T.W. and Chen, W.J., 2011. Investigation of multiply composite artificial bars for Bragg scattering of water waves, Coastal Engineering Journal, 53(4), 521–548.
Wang, G., Liang, Q.H., Shi, F.Y. and Zheng, J.H., 2021. Analytical and numerical investigation of trapped ocean waves along a submerged ridge, Journal of Fluid Mechanics, 915, A54.
Wang, S.K., Hsu, T.W., Tsai, L.H. and Chen, S.H., 2006. An application of Miles’ theory to Bragg scattering of water waves by doubly composite artificial bars, Ocean Engineering, 33(3–4), 331–349.
Zakharov, V.E., 1968. Stability of periodic waves of finite amplitude on the surface of a deep fluid, Journal of Applied Mechanics and Technical Physics, 9(2), 190–194.
Zhang, H.M., Tao, A.F., Tu, J.H., Su, J.W. and **e, S.Y., 2021. The focusing waves induced by Bragg resonance with V-shaped undulating bottom, Journal of Marine Science and Engineering, 9(7), 708.
Zhang, Y., Guo, J., Liu, Q., Huang, W.R., Bi, C.W. and Zhao, Y.P., 2021. Storm damage risk assessment for offshore cage culture, Aquacultural Engineering, 95, 102198.
Zheng, J.H., Yao, Y., Chen, S.G., Chen, S.B. and Zhang, Q.M., 2020. Laboratory study on wave-induced setup and wave-driven current in a 2DH reef-lagoon-channel system, Coastal Engineering, 162, 103772.
Author information
Authors and Affiliations
Corresponding author
Additional information
Foundation item
This research work is financially supported by the National Natural Science Foundation of China (Grant Nos. U1706230 and 51379071), the Key Project of NSFC-Shandong Joint Research Funding POW3C (Grant No. U1906230), and the National Science Fund for Distinguished Young Scholars (Grant No. 51425901).
Rights and permissions
About this article
Cite this article
Peng, J., Tao, Af., Fan, J. et al. On the Downshift of Wave Frequency for Bragg Resonance. China Ocean Eng 36, 76–85 (2022). https://doi.org/10.1007/s13344-022-0006-y
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s13344-022-0006-y