| Co-Investigator(Kenkyū-buntansha) |
FUJIWARA Hirokazu hachinohe National College of Technology, Associate Professor, 助教授 (70199389)
MINAMI Masato hachinohe National College of Technology, Associate Professor, 助教授 (60280319)
SEKITA Kenji Tokai University, Marine Science and Technology, Professor, 海洋学部, 教授 (90287045)
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| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2001: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2000: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1999: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Research Abstract |
Based on the result which carried out continuation measurement of the wave and the wind-sea near the sea surface using the multi-point anemometer, this research asked the average wind velocity distribution for the roughness parameter (Z_O) and the friction coefficient (C_D), and considered the relation with the significant wave height (H_<1/3>). Moreover, we considered the relation between a non-dimension roughness parameter (gZ_0/u*^2) and a wave age (C_P/u*), and the relation between the non-dimension parameter (u*^2/υσ_p) showing a sea surface situation, and a frictional resistance coefficient (C_D). Furthermore, past research, and comparison and examination were performed about the turbulent intensity and spectrum which are the turbulent flow characteristic. Observation was performed using the sea technical general research institution (Ministry of Land, Infrastructure and Transport) in the place of 250m of the Oigawa mouth-of-a-river offings. Wind velocity measurement was performe
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d by attaching eight sensors of a multi-point anemometer in the pole for measurement at intervals of 0.5-1.5m. Moreover, simultaneous measurement also of an ultrasonic water gauge, fine pressure gauge, a thermometer, and the ultrasonic anemometer was attached and carried out. Sampling time is 5Hz and the number of data of 1 measurementis 16384.
The main results are as follows. A roughness parameter (Z_0) tends to become large as standard wind velocity (V_<10>) increases, and in V_<10>>8m, the increase rate became large. It was set to 0.00023<Z0<0.034 in this 2.4m/s that carried out the measurement range. Next, the friction coefficient (C_D) for which it asked as a Karman constant k=0.4 increased linearly as standard wind velocity (V_<10>) became large, and it was set to 0.0014<C_D<0.0049 in this measurement wind velocity range. Moreover, a friction coefficient (C_D) increases exponentially as the significant wave height (H_<1β>) increases in the range which are 0.8-1.2m, a friction coefficient (C_D) increases exponentially as a roughness parameter (Z_0) increases. It was mostly in agreement with the formula which Toda and Koga (1986) proposed in the domain to which the wave with large wave age progressed enough from the relation between a non-dimension roughness parameter (gZ_0/u*^2) and a wave age (C_P/u*). In the relation between a frictional resistance coefficient (C_D) and a non-dimension parameter (u*2/υσ_p), an increase of u*^2/υσ_P also increases C_D. I am doing one The non-dimension wind velocity spectrum became a value comparatively near the spectrum form of Hino the spectrum form of Davenport, and near the spectrum peak at the low frequency side. However, A result with larger attenuation than Davenport, Hino, and the spectrum form of Ochi and Shin was brought at the high frequency side. Less
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