Palabras clave
submerged breakwater
wave
PIV measurements
Cómo citar
Resumen
The objective of the present study is to investigate the flow field for waves propagating over a submerged poro-elastic breakwater. Particle Image Velocimetry (PIV) measurements were performed in wave conditions with breakwaters made of different materials. The experimental results were compared for various rigid and impermeable, elastic and impermeable, as well as poro-elastic cases. Measurements of wave reflection and transmission induced by soft and permeable submerged breakwaters are both carried out. The results show that the oscillatory motion of elastic submerged breakwater can induce extra reflective waves and result in a larger reflection coefficient. Positive (counterclockwise) and negative (clockwise) vortices are generated due to corner separation and pressure gradients. The negative vortex obtained in a poro-elastic breakwater is generated by the surface friction at the top of the structure. Because of the permeability, it is found that the negative vortex at the upstream side of the elastic and permeable case is smaller than that of the rigid and impermeable one. In contrast, the positive vortex at the downstream side of the poro-elastic case is larger than that seen with the other two cases. It is concluded that a poro-elastic breakwater would induce different wave reflections and flow patterns from those seen with the other cases due to its particular wave and structure interactions.Referencias
Chang, K.A., T.J. Hsu, and P.L.F. Liu. 2001. Vortex generation and evolution in water waves propagating over a submerged rectangular obstacle, part I. solitary waves, Coastal Engineering, 44, 13-36.http://dx.doi.org/10.1016/S0378-3839(01)00019-9
Chang, K.A., T.J. Hsu, and P.L.F. Liu. 2005. Vortex generation and evolution in water waves propagating over a submerged rectangular obstacle, part II: cnoidal waves, Coastal Engineering, 52, 257-283.http://dx.doi.org/10.1016/j.coastaleng.2004.11.006
Ghisalberti, M., and H.M. Nepf. 2008. Sallow flows over a permeable medium: The hydrodynamics of submerged aquatic canopies, Transport in Porous Media, 78, 385-403.http://dx.doi.org/10.1007/s11242-009-9434-x
Lai, J.W. 2009. Digital image technique and data application on monitoring water surface in wave flume, Ph.D. Thesis, National Cheng Kung University, Taiwan, ROC.
Lai, J.W., Y.J. Lan, T.W. Hsu, C.H. Ting, and C.C. Chang. 2009. Application of digital image process on observing the motions of wave and a series of poro-elastic submerged breakwaters, Proceedings of Coastal Dynamics 2009, paper No. 142.
Lan, Y.J., and J.F. Lee. 2010. On Waves Propagating over a Submerged Poro-Elastic Structure, Ocean Engineering, 37, 705-717.http://dx.doi.org/10.1016/j.oceaneng.2010.02.001
Lan, Y.J., T.W. Hsu, J.W. Lai, C.C. Chang, and C.H. Ting. 2011. Bragg scattering of waves propagating over a series of poro-elastic submerged breakwaters, Wave Motion, 48, 1-12.http://dx.doi.org/10.1016/j.wavemoti.2010.06.002
Li, C.W., and K. Yan. 2007. Numerical investigation of wave-current-vegetation interaction, Journal of Hydraulic Engineering, 133, 794-803.http://dx.doi.org/10.1061/(ASCE)0733-9429(2007)133:7(794)
Mansard, E.P.D., and E.R. Funke. 1980. The measurement of incident and reflected spectra using a least squares method, Proceedings of the 17th International Conference on Coastal Engineering, ASCE, 2, 154-172.
Muir Wood, A.M. 1969. Coastal hydraulics, New York :Gordon and Breach, 187p.
Ohyama, T., M. Tanaka, T. Kiyokawa, T. Uda, and Y. Murai. 1989. Transmission and reflection characteristics of waves over a submerged flexible mound, Coastal Engineering in Japan, 32(1), 53-68.
Petti, M., P.A. Quinn, G. Liberatore, and W.J. Easson. 1994. Wave velocity field measurement over a submerged breakwater. Proceedings of the 24th International Conference on Coastal Engineering, ASCE, 525-539.
Prinos, P., V. Stratigaki, E. Manca, I. Losada, J.L. Lara, M. Sclavo, I. Cáceres, and A. Sánchez-Arcilla. 2010. Wave propagation over Posidonia oceanica: large scale experiments, Proceedings of the HYDEALAB III Joint User Meeting, Hannover.
PMid:21968505 PMCid:3180032
Raffel, M., C. Willert, S. Wereley, and J. Kompenhans. 2007. Particle image velocimetry : A practical guide, 2nd ed. Springer. Stratigaki, V., E. Manca, P. Prinos, I. Losada, J.L. Lara, M. Sclavo, C.L. Amos, I. Cáceres, and A.
Sánchez-Arcilla. 2011. Large-scale experiments on wave propagation over posidonia oceanica, Journal of Hydraulic Research, 49(S1), 31-43.
Ting, F.C.K., and Y.K. Kim. 1994. Vortex generation in water waves propagation over a submerged obstacle, Coastal Engineering, 24, 23-49.http://dx.doi.org/10.1016/0378-3839(94)90025-6
Wang, K.H., and X. Ren. 1993. Water waves on flexible and porous breakwaters, Journal of Engineering Mechanics, 119, 1025-1047.