WAVE HEIGHTS RECOVERY FROM SUBSURFACE PRESSURES UPON A SMALL VERTICAL CYLINDER

Tri Cao Mai, Torsten Schlurmann

Abstract


In this paper, the fluctuation of water surface has been recovered from subsurface dynamic pressures exerted on a small vertical cylinder of a tripod structure and it finds that the wave heights can be estimated accurately from the pressures measured at θ = 180°. Seven pressure transducers were mounted around the cylinder to get the circumference distribution of the dynamic pressures. The time histories of the water surface fluctuations and the concurrent dynamic pressures upon the cylinder have been analyzed in frequency domain. A part of the linear diffraction theory of MacCamy & Fuchs has been applied to analyze the experimental data. Additionally, the empirical factor, which is the ratio of the measured and recovered wave height, is presented.

Keywords


wave height; dynamic pressure; small vertical cylinder; transfer function; empirical factor

References


Bishop, C.T. and Donelan, M.A., "Measuring waves with pressure transducers". Coastal Engineering 11, 309-328 (1987).http://dx.doi.org/10.1016/0378-3839(87)90031-7

Cavaleri, L., "Wave measurement using pressure transducer". OceanologicaActa 3 (No. 3), 339-346 (1980).

Escher, J. and Schlurmann, T., "On the recovery of the free surface from the pressure within periodic traveling water waves". Journal of Nonlinear Mathematical Physics, V5-2, 50-57 (2008).

Huang, M.C. and Tsai, C.H., "Pressure transfer function in time and time-frequency domains". Ocean Engineering 35, 1203-1210 (2008).http://dx.doi.org/10.1016/j.oceaneng.2008.04.005

Kuo, Y. Y. and Chiu, Y. F., "Transfer function between the wave height and wave pressure for progressive waves". Coastal Engineering 23, 81-93 (1994).http://dx.doi.org/10.1016/0378-3839(94)90016-7

MacCamy, R.C. and Fuchs, R.A., "Wave forces on piles: a diffraction theory". U.S. Army Corps of Engineering, Beach Erosion Board, Washington, D.C., Tech. Mem. No. 69 (1954).

Sumer, B. M., Fredsøe, J., "Hydrodynamics around cylindrical structures" (Revised Edition). World Scientific Publishing Co. Pte. Ltd., Denmark (2006).

Sundar, V., Neelamani, S. And Vendhan, C.P., "Dynamic pressures on a large vertical cylinder due to random waves". Coastal Engineering 13, 83-104 (1989).

Tsai, C.H., Huang, M.C., Young, F.J., Lin, Y.C. and Li, H.W., "On the recovery of surface wave by pressure transfer function". Ocean Engineering 32, 1247-1259 (2005).http://dx.doi.org/10.1016/j.oceaneng.2004.10.020


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