水産工学
Online ISSN : 2189-7131
Print ISSN : 0916-7617
ISSN-L : 0916-7617
海洋構造物の流体力に及ぼす流れと波の相乗効果
木村 晴保 紙井 泰典
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ジャーナル オープンアクセス

2013 年 50 巻 2 号 p. 113-117

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Marine structures like cylindrical bridge piers are exposed to hydrodynamic force F (=F_M + F_D, where, F_M is mass force and F_D is drag force) exerted by wave and current. While wave generates F_M and part of F_D, current generates residual part of F_D. F is calculated by Morison's formula. Ocean current velocity u is broken down into steady flow velocity ν and fluctuating wave velocity ν_w cosωt (where, ν_w is half amplitude horizontal velocity of wave, angular velocity ω = 2π/T, T is wave period and t is time). Drag force F_D (= F^^-_D + F^^〜_D, where, F^^-_D is steady drag force and F^^〜_D is fluctuating drag force) has been calculated by Fourier transform. Conclusions are as follows: (1) Steady drag force F^^-_D acting on a structure, which is primarily generated by steady velocity ν, increases under the existence of fluctuating velocity ν_w cosωt. (2) Fluctuating drag force F^^〜_D acting on a structure which is primarily generated by ν_w, increases in the same frequency components as that of wave under the existence of steady velocity ν.

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© 2013 日本水産工学会
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