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Indexed by:期刊论文

Date of Publication:2010-10-01

Journal:JOURNAL OF HYDRODYNAMICS

Included Journals:SCIE、Scopus

Volume:22

Issue:5

Page Number:926-931

ISSN No.:1001-6058

Key Words:low-frequency; ISSC; full QTF; Newman's approximation

Abstract:For deep water offshore structures, the second order different frequency force may induce large responses in the horizontal directions. The second order different frequency force is usually computed by the Fourier transformation of the second order quadratic transform function (QTF), which is hard to be obtained due to its complexity, time consuming and the influence of 'irregular frequency' in its computation. In practical application Newman's approximation[5] is widely used, without considering its viability.
   Based on a higher-order boundary element method, a numerical model is established for complex solution of second-order diffractions and radiations at different frequencies in bichromatic incident waves. The second-order quadratic transform functions are obtained by the integration of second-order fluid pressure on the body surface. With application of Teng et al's method[9], full QTF's are computed for a typical TLP model ISSC. Computation shows that the second-order quadratic functions have distinct distribution at lower frequency ranges. Comparisons are made on the Newman's approximation with the full difference-frequency QTF.