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A general approach that utilizes both spectral and extremal statistical methods are utilized to investigate the time series of flow-induced response behavior of a flexible horizontal cylinder subject to both random waves and constant current conditions. The cylinder model was 29 m long and had a slenderness ratio of approximately 760. The random waves were generated using a JONSWAP wave amplitude spectrum. In addition, for some tests, the cylinder was towed at two different speeds to simulate the combined loading of random waves and constant current conditions. The data were initially analyzed using standard spectral analyses to interpret the cylinder’s flow-induced response behavior and relate the findings to traditional deterministic parameters. Further analyses were performed using a generalized extreme value (GEV) distribution procedure that involved dividing the time series into blocks and fitting the block maxima of the extreme values in the measured response time series data. The Anderson–Darling (AD) test criterion and quantile plots were then used to assess whether the GEV distribution provides a satisfactory fit to the data capturing the statistical characteristics in the flexible cylinder’s flow-induced response behavior, which was stochastic in nature. For the data set analyzed, the extremal GEV methodology presented was observed to provide excellent results for the random wave cases and moderately good-to-good results for the combined random wave and constant current cases.
combined loading, currents, flexible horizontal cylinder, flow-induced response, GEV extremal statistics, random waves, spectral analysis
[1] Vandiver, J.K., Dimensionless parameters important to the prediction of vortex-induced vibration of long, flexible cylinders in ocean currents. Journal of Fluids and Structures, 7(5), pp. 423–455, 1993. https://doi.org/10.1006/jfls.1993.1028
[2] Griffin, O.M., Skop, R.A. & Ramberg, S.E., Resonant, Vortex-Excited Vibrations of Structures and Cable Systems. Offshore Technology Conference, Houston, 1975.
[3] Sarpkaya, T., Vortex induced oscillations. Journal of Applied Mechanics, 46(2), pp. 241–258, 1979. https://doi.org/10.1115/1.3424537
[4] Sarpkaya, T., A critical review of the intrinsic nature of VIV, Journal of Fluids and Structures, 19(4), pp. 389–447, 2004.
[5] Zdravkovich, M.M., On origins of hysteretic responses of a circular cylinder induced by vortex shedding. Zeitschrift fur Flugwissenschaften und Weltraumforschung (Journal of Flight Sciences and Space Research), 14, pp. 47–58. Springer-Verlag, 1990.
[6] Vandiver, J.K., Damping parameters for flow-induced vibration. Journal of Fluids and Structures, 35, pp. 105–119, 2012. https://doi.org/10.1016/j.jfluidstructs.2012.07.002
[7] Klamo, J.T., Leonard, A. & Roshko, A., On the Maximum Amplitude of a Freely Vibrat- ing Cylinder in Cross-Flow. Journal of Fluids and Structures, 21(4), pp. 429–434, 2005. https://doi.org/10.1016/j.jfluidstructs.2005.07.010
[8] Swithenbank, S.B., Vandiver, J.K., Larsen, C.M. & Lie, H., Reynolds Number Dependence of Flexible Cylinder VIV Response Data. Proceedings of the International Conference on Offshore Mechanics and Artic Engineering, OMAE2008-57045, 2008.
[9] Resvanis, T.L., Jhingran, V., Vandiver, J.K. & Liapis, S., Reynolds number effects on the vortex-induced vibration of flexible marine risers. Proceedings of the ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering, OMAE 2012-83565, 2012.
[10] Govardhan, R.N. & Williamson, C.H.K., Defining the Modified Griffin Plot in Vor- tex-Induced Vibration: Revealing the Effect of Reynolds Number Using Controlled Damping. Journal of Fluid Mechanics, 561, 147–180, 2006. https://doi.org/10.1017/s0022112006000310
[11] MARINTEK, Shell Riser VIV Tests Main Report, No. 580233.00.0, 2011.
[12] Resvanis, T.L. & Vandiver, J.K., Response variability in flexible cylinder VIV model test data. Proceedings of the ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering, OMAE 2017-61516, 2017.
[13] Chitwood, J.S., Vortex-induced vibration of a slender horizontal cylinder in currents and waves, OTRC report No. 2/98-A9575, 1998.
[14] Nigam, Introduction to Random Vibrations. The MIT Press, Cambridge, MA, 1983.
[15] Cartwright, D.E. & Longuet-Higgins M.S., The statistical distribution of the maxima of a random function. Proc Royal Soc Lond A, 237:212–232, 1956. https://doi.org/10.1098/rspa.1956.0173
[16] Coles S., An introduction to statistical modeling of extreme values. Spinger, Verlag London, 2001.
[17] D’Agostino, R.B. & Stephens, M.A., eds., Goodness-of-fit techniques. Marcel Dekker, New York, 1986.
[18] Cramér H., On the composition of elementary errors. Skand. Aktuarietids, 11, pp. 13–74, 141–180, 1928.
[19] Anderson, T.W. & Darling, D.A., A test for goodness of fit. Journal of the American Statistical Association, 49(268), pp. 765–769, 1954. https://doi.org/10.1080/0162145 9.1954.10501232
[20] Welch, P.D., The use of Fast Fourier Transform for the estimation of power spectra: A method based on time averaging over short, modified periodograms. IEEE Transactions on Audio and Electroacoustics, AU-15(2), 70–73, 1967. https://doi.org/10.1109/ tau.1967.1161901
[21] R Core Team, R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria, 2019. URL https://www.R-project.org/