著者

青木 克巳 武藤 浩司 岡永 博夫

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.77, no.775, pp.793-802, 2011 (Released:2011-03-25)

参考文献数

15

被引用文献数

1

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The present study clarifies the effects of dimples for drag and lift on a sphere with rotation. The sphere with dimples has 328 arc type dimples on its surface uniformly. The present study measures velocity distribution in wake and pressure distribution on a sphere surface, and visualizes flow around a sphere by the spark tracing method for the case in which Reynolds number Re=0.4×105-1.3×105. For the case of a smooth sphere, separation point on deceleration side shifts downstream remarkably as spin rate ratio (circumferential velocity of a sphere / free stream velocity) increases. The pressure distribution on deceleration side decreases compared to that on acceleration side. The wake becomes small and shifts opposite direction of rotation. Therefore, the drag reduces, and the lift becomes negative. For the case of a sphere with dimples, this phenomenon occurs for the case in which critical Reynolds number Re=0.5×105. The separation point on acceleration side shifts downstream, and the separation point on deceleration side shifts upstream as spin rate ratio increases for the case in which super critical Reynolds number Re=1.3×105. The pressure distribution on acceleration side decreases compared to that on deceleration side. In addition, the pressure distribution on outside dimple decreases compared to that on inside dimple. The wake becomes large and shifts direction of rotation. Therefore, the drag and positive lift increase.

著者

中山 泰喜 青木 克巳 沖 真

出版者

社団法人 可視化情報学会

雑誌

可視化情報学会誌 (ISSN:09164731)

巻号頁・発行日

vol.25, no.Supplement2, pp.339-342, 2005-10-01 (Released:2009-07-31)

参考文献数

2

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It is said that the Jomon Age began about12, 000 years ago and continued till about 2, 500 years ago. The potteries of that age are known as Jomon pottery. Among them, a pottery discovered from the Umataka ruin in Niigata Prefecture in 1931 has an excellent shape. It is said that this pottery was made about 4, 500 years ago. Jomon potteries of similar artistic styles have been discovered in various parts of Japan. These potteries have very nice shapes, but the pottery discovered from the Umataka ruin excels other potteries by its excellent proportion. From the shape of lip, it was named "Kaen pottery" meaning " flame pottery" . However, from the patterns of its lip and side wall, it is more appropriate to consider that they are related to water flow. In this report, this hypothesis by a visualization method using the pollen of cedar and pine trees, and computer simulation.

著者

青木 克巳

出版者

Japan Association for Wind Engineering

雑誌

日本風工学会誌 (ISSN:09121935)

巻号頁・発行日

vol.2004, no.100, pp.61-67, 2004-07-31 (Released:2010-06-04)

参考文献数

6

被引用文献数

1 1

著者

青木 克巳 岡永 博夫 長瀬 二郎

出版者

一般社団法人 日本機械学会

雑誌

シンポジウム: スポーツ・アンド・ヒューマン・ダイナミクス講演論文集

巻号頁・発行日

vol.2013, pp._241-1_-_241-10_, 2013

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In this report, aerodynamic characteristic such as lift and drag of official rubber-balls used in the game of the baseball are studied experimentally. And the aerodynamic characteristic of these rubber-ball is compared and is examined with the aerodynamic characteristic of smooth sphere and sphere with dimple and the Major League ball. In addition, the aerodynamic characteristic for seam angle and spin rate ratio ratioα (=V/U, V: peripheral velocity of test balls, U: flow velocity)is also clarified. And, the flow pattern around the test balls are visualized by the spark tracing method. Following conclusions were got from these results. (1) The dimpled rubber-ball has a critical region where the drag coefficient decreases in the same way as the smooth surface balls. (2)Depending on the surface structure of test balls, the aerodynamic characteristics differ significantly. When dimples are added to the balls with seams, the critical region moves toward the lower Reynolds number side, but the minimum drag coefficient increases. (3)About the rubber-ball and Major League ball, C_D shows the almost same values without rotation. However at the rotational state, C_D of the Rubber-ball is lower than that of the Major League ball . (4)The values of C_D take different values depending on type A〜E and become large as α increases. The values of C_L stand in a same line which rises as α increase.

著者

中山 泰喜 青木 克巳 沖 真

出版者

社団法人 可視化情報学会

雑誌

可視化情報学会誌 (ISSN:09164731)

巻号頁・発行日

vol.26, no.Supplement1, pp.223-226, 2006-07-01 (Released:2009-12-08)

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It is said that the Jomon Age began about 12, 000 years ago and continued till about 2, 500 years ago. The potteries of that age are known as Jomon pottery. Among them, a pottery discovered from the Umataka ruin in Niigata Prefecture in 1931 has an excellent shape. It is said that this pottery was made about 4, 500 years ago. Jomon potteries of similar artistic styles have been discovered in various parts of Japan. These potteries have very nice shapes, but the pottery discovered from the Umataka ruin excels other potteries by its excellent proportion. In this report, it was made clear that the vortex patterns of side wall consist of twin vortex and Karman vortex applying visualization methods using the pollen of cedar and pine trees, and computer simulation.

著者

中山 泰喜 菊池 徹夫 沖 真 青木 克巳 丸岡 計

出版者

社団法人 可視化情報学会

雑誌

可視化情報学会誌 (ISSN:09164731)

巻号頁・発行日

vol.24, no.Supplement1, pp.165-168, 2004-07-01 (Released:2009-07-31)

参考文献数

1

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It is said that Jomon Age began about 12, 000 years ago and continued till about 2, 500 years ago. The potteries of that age are known as Jomon pottery. Among them, a pottery discovered from the Umataka ruin in Niigata Prefecture in 1931 has an excellent shape. It is said that this pottery was made about 4, 500 years ago. Jomon potteries of similar artistic styles have been discovered in various parts of Japan. These potteries have very nice shapes, but the pottery discovered from the Umataka ruin excels other potteries by its excellent proportion. From the shape of lip, it was named "Kaen pottery". However, from the patterns of its lip and side wall, it is more appropriate to consider that they are related to water flow. In this report this hypothesis is examined by a visualization method using the pollen of cedar and pine trees, and computer simulation.

著者

中山 泰喜 菊地 徹夫 青木 克巳

出版者

日本情報考古学会

雑誌

情報考古学 (ISSN:13424084)

巻号頁・発行日

vol.10, no.1, pp.1-8, 2004

被引用文献数

2

著者

中山 泰喜 青木 克巳 沖 真

出版者

社団法人 可視化情報学会

雑誌

可視化情報学会誌 (ISSN:09164731)

巻号頁・発行日

vol.22, no.1Supplement, pp.161-164, 2002-07-01 (Released:2009-09-03)

参考文献数

2

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It is said that the Jyoumon Age Culture continued from 16, 000 years ago to 2, 500 years ago and the people who bore the culture is called Joumon-jin. Earthen ware that were produced by Jyoumon-jin are called Joumon-doki. Jyoumon-doki have been discovered in various parts of Japan and there are many kinds of them. Among them, one discovered at Umataka-ruins in Niigata Prefecture at the end of 1931 is very famous for its nice patterns and it was named Kaen-doki.The patterns on its lip and side wall are related to the water flow, the authors believe. The nice vortex patters of Kaen-doki put on their side wall are two kinds of vortex observed down stream of piles and rocks in the river acting the pollen and fallen leaves, etc. as tracers.This fact was appeared again using Floating Tracer Method, one of the visualization methods of modern age, and the computer simulation.

著者

青木 克巳 斉藤 昌邦 中山 泰喜

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:03875016)

巻号頁・発行日

vol.51, no.469, pp.p2889-2896, 1985-09

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本論文は旋回流を伴った円筒管内再循環流領域の生成に関して述べたものである.本研究では,レイノズル数1500までに対して,ノズルからの一次流れと旋回器からの二次流れの比,ならびに旋回角の変化に対する数値計算と実験が行われている.そして実験値と計算結果は良く位置している.これらの結果から,流量比,旋回角,レイノルズ数の変化に対する流れ様式を再循環流領域の大きさ,形状などを明らかにした.