ESTIMATION OF BOUND AND RELEASED INFRAGRAVITY WAVES BASED ON WAVE OBSERVATION AND NUMERICAL SIMULATION IN SHALLOW WATER
AbstractIt is mentioned that observed infragravity waves consist of bound waves propagating with short-wave groups, released waves due to reduction of short crest waves and free waves existing in a field. Though it is difficult to distinguish among them, a standard spectrum for infragravity waves is defined by using a relation to a wind wave spectrum. In this study, a comprehensive definition of standard spectrum is newly proposed to estimate infragravity wave heights with the relation between the ratio of wave height and the ursell number of observed wave property, represented by selected data of wave observation in shallow water. Moreover, the release process of bound waves at a harbor entrance is reproduced in numerical simulation using a Boussinesq model for short-wave transformation. These results are verified by comparison to infragravity waves observed at outside/inside of a harbor for a month.
Hiraishi, T., S. Kouno, S. Tamashiro and J. Hasegawa (1997): Standard spectrum of long period waves for harbor facility design, Proc. Coastal Eng., JSCE, Vol.44, pp.246-250.
Hirayama, K., J. Naganuma and Y. Uno (2015): Verification of infragravity waves generated at harbor entrance by using a Boussinesq model, Proc. 25th ISOPE, Hawaii, pp.1176-1182.
Kato, H. and H. Nobuoka (2005): Properties of secondorder waves in nonlinear numerical simulations, Proc. Coastal Eng., JSCE, Vol.52, pp.136-140.
Lopez. M., I. Lopez and G. Iglesios (2015): Hindcasting long waves in a port: an ANN approach, Coastal Eng. J., World Sicentific Co. and JSCE, Vol.57, No.4, 20p.
Mitsuyasu.H., F. Tasai, T. Suhara, S. Mizuno, M. Ohkusu, T. Honda and K. Rikiishi (1980): Observation of the power spectrum of ocean waves using a cloverleaf buoy, J. of Physical Oceanography, Vol. 10, pp.286-296.
Ottesen-Hansen, N.E., S.E. Sand, H. Lundgren, T. Sorensen and H. Gravesen (1980): Correct reproduction of group induced long waves, Proc. 17th ICCE, Sydney, ASCE, pp.784-800.
Sand, S.E. (1982): Long waves in directional seas, Coastal Engineering, ELSEVIER, vol.6, pp.195-208.
Schaffer H.A. (1993): Infragravity waves induced by short-wave groups, Journal of Fluid Mechanics, vol.247, pp.551-588.
Sekimoto, T., Y. Moriya and M. Mizuguchi (2000): Theoretical Study on Estimations of the Free Long Period Waves†, Proc Coastal Engineering, JSCE, Vol.47, pp.236- 240.