## Abstract

Field tests were carried out over a two-year period to obtain the drag and inertia coefficients of a surface-piercing vertical cylinder fixed in irregular waves using an ocean research platform. The platform was set 2 km offshore for collection of ocean environmental data on wind, waves and current. The wave forces were measured with two 2-component dynamometers set at either end of the test cylinder: Data on waves were recorded using a wave height meter array, and orbital velocity was also measured with a 3-component electromagnetic current meter to confirm the accuracy of estimated values of orbital velocity calculated from wave data and linear wave theory. The following was found. (a) the values of C_{D} and C_{M} obtained from least squares fit of the complete force time series of a random wave record were well ordered as a function of Keulegan-Carpenter number K_{C} defined by significant orbital displacement and the diameter of the cylinder, but those determined by the least squares fit on a wave-by-wave basis were widely scattered. (b) ocean wave force exerted on the cylinder was well represented by Morison's formula; the ratio of predicted wave force by this formula to the directly measured force was 90%, and the ratio was very stable throughout the experiments.

Original language | English |
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Pages (from-to) | 161-167 |

Number of pages | 7 |

Journal | International Journal of Offshore and Polar Engineering |

Volume | 2 |

Issue number | 3 |

Publication status | Published - Sept 1992 |

## All Science Journal Classification (ASJC) codes

- Civil and Structural Engineering
- Ocean Engineering
- Mechanical Engineering