著者

江端 重葉 安田 孝宏 南川 久人 宮本 悠治 里深 信行

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集B編 (ISSN:18848346)

巻号頁・発行日

vol.79, no.806, pp.1886-1899, 2013 (Released:2013-10-25)

参考文献数

8

被引用文献数

1 3

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Underwater glider is the glider to use for environmental researches in lake and sea. The Reynolds number of flow around underwater glider is between about 104 ~ 105 and the research for the aerodynamic characteristics of such low Reynolds number region is not so much. So in this study, we investigate the aerodynamic characteristics for various airfoils of under-water glider at low Reynolds number by the towing water tank experiment and 3-dimensional numerical analysis using STAR-CCM+ by IDAJ co. ltd. As results of experiment, the lift-drag ratio of airfoils with camber become larger than those of flat plate. As results of numerical analysis, the effect of maximum camber ratio and maximum camber position and thickness ratio on aerodynamic characteristics and optimum cross-sectional shape of wing for underwater glider are found.

著者

南川 久人 藤原 海 栗本 遼 安田 孝宏 原田 英美子 畑 直樹

出版者

日本実験力学会

雑誌

実験力学 (ISSN:13464930)

巻号頁・発行日

vol.16, no.1, pp.77-83, 2016-04-11 (Released:2016-04-11)

参考文献数

17

被引用文献数

1

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Effects of microbubbles on germination and growth in deep flow technique of spinach (Spinacia oleracea) were investigated. In the germination experiment, four experiment plots; (1) underwater germination with microbubble water plot (MB plot), (2) underwater germination with aerated water plot (Aeration plot), (3) underwater germination with water plot (Water plot), (4) germination on wet cotton plot (Control plot), were used. Two hundred individuals were germinated for each plot. Germination rate of MB plot after 7 days was about twice as high as that of Aeration plot and Control plot. In the growth experiment, three experiment plots; (1) tenth solution concentration water with microbubble plot (MB plot), (2) tenth solution concentration water plot (Aeration plot), (3) full solution concentration water plot (Control plot), were used. Twelve individuals were grown for each plot. Leaves weight of MB plot was as much as that of Control plot. In contrast, plant physiological disorders appeared in all plants of Aeration plot. Multi-element determination revealed that K concentration of Aeration plot was lower than that of the others plots. These results indicate that microbubbles contribute to the plants absorbing the nutrient from roots.

著者

富山 明男 宋 明良 南川 久人 坂口 忠司

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.57, no.539, pp.2167-2173, 1991-07-25

被引用文献数

6

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In order to examine the feasibility of direct simulation of bubbly flows, the applicability of the VOF (volume of fluid) method to the analyses of a single rising bubble was examined in this study. Calculated bubble shapes and terminal velocities under wide ranges of Eotvos number and Morton number were compared with the experimental data summarized by Grace et al. Except for the cases when bubble shapes are spherical-cap and skirted, the VOF method could predict them well by assigning only eight cells to the bubble diameter. Hence, it was confirmed that some modification of this method will enable us to simulate bubbly flows directly under a wide-range of flow conditions. Moreover, the relation between a bubble shape and velocity distribution was examined within the ranges in which the VOF method is valid. It was found that the secondary vortex appearing in wobbling bubbles induces the velocity component normal to the bubble interface, and this velocity is one of the causes of the wobbling shape of the bubble.