著者
郡司 博史 酒井 敏
出版者
日本流体力学会
雑誌
日本流体力学会年会講演論文集
巻号頁・発行日
vol.2002, pp.92-93, 2002

A milk crown is a very attractive phenomenon. However, it is very difficult to catch a continuous picture. Therefore, there is almost no systematic research. Then, with the digital Video Camera, we took the continuous image and analyzed them. The parameters of the experiment are the velocity of the waterdrops which collides with a thin liquid layer, the depth of a liquid layer, and the viscosity of fluid of the experiment. Surprisingly, we found that crown-like structure at about 10ms to 30ms after the collision of waterdrop expand at the same speed unrelated to the parameters.
著者
皆川 佑介 小尾 晋之介 益田 重明
出版者
日本流体力学会
雑誌
日本流体力学会年会講演論文集
巻号頁・発行日
vol.2002, pp.390-391, 2002

An experimental study has been conducted for a round jet impinging perpendicularly onto a rotating disk. The mean velocity and turbulence statistics are measured by a single component LDV. The jet is issued from a pipe, in which the fully developed turbulent flow is ensured. The disk is set 5 diameters from the pipe exit. The Reynolds number based on the bulk velocity and the pipe diameter is set constant at 1.4E4 while the rotation speed of the disk has been varied between 0 and 1,500rpm. The velocity components in radial and circumferential directions are measured at some selected radial locations. The effect of the disk rotation has not become remarkable until the rotating speed of the disk reaches certain value, which has been indicated by the reduction of the half-width of wall-jet and the increase in the maximum radial mean velocity. The changes in the circumferential velocity component and in the turbulence statistics are fond to be marginal.
著者
佐藤,和雄
出版者
日本流体力学会
雑誌
日本流体力学会年会講演論文集
巻号頁・発行日
vol.2002, 2002-07-23

Force measurement test of a standard model HB-2 was conducted at the high enthalpy shock tunnel HIEST. The result obtained at lowest enthalpy condition, in which real gas effect is supposed to be negligible, was compared with the blowdown type hypersonic wind tunnel HWT1 and a good agreement was obtained at zero angle of attack. Real gas effect was also studied by changing stagnation enthalpy up to 11MJ/kg and the significant decrease in axial force with increase in stagnation enthalpy was observed.
著者
横田,祥
出版者
日本流体力学会
雑誌
日本流体力学会年会講演論文集
巻号頁・発行日
vol.2010, 2010-09-09

In the terrestrial and planetary atmospheres, vortices that exhibit a polygonal shape are occasionally observed even when the external conditions are nearly axisymmetric. Similar phenomena are also found in laboratory experiments in which water layer in a right cylindrical tank is driven by a rapidly-rotating bottom disk. In this study, we have studied these phenomena by means of laboratory experiments and a linear stability theory. It is found that the characteristics of the vortices in the laboratory experiments are well explained by those of the fastest growing waves caused by a horizontal shear instability of the basic flow. Thus, the polygons observed in the laboratory experiments are likely to be caused by a shear instability.
著者
福本 康秀
出版者
日本流体力学会
雑誌
ながれ : 日本流体力学会誌 (ISSN:02863154)
巻号頁・発行日
vol.25, no.3, pp.265-280, 2006-06-25
参考文献数
40
被引用文献数
8
著者
森脇 亮 石井 宏明 神田 学
出版者
日本流体力学会
雑誌
日本流体力学会年会講演論文集 (ISSN:13428004)
巻号頁・発行日
vol.2000, pp.221-222, 2000-07-25
参考文献数
3

Field observation and numerical simulations were performed to investigate the atmospheric structure and distribution of air pollutants over Tokyo Bay. The following results were obtained : 1) Observed diurnal variation of potential temperature over Tokyo Bay is different from over the land or the sea. 2) There is a descending flow over Tokyo Bay. and it is the compensation for the divergent flow pattern. The peak value of descending flow exits at the height of 300-500m. 3) The rise in potential temperature in the daytime is caused by the adiabatic heating of descending flow. 4) Vertical gradient of CO_2 is positive over the bay. It suggests that CO_2 is transported over Tokyo Bay from surrounding high emission area.
著者
三村 和男
出版者
日本流体力学会
雑誌
日本流体力学会年会講演論文集 (ISSN:13428004)
巻号頁・発行日
vol.2007, 2007-08-06

Thermal convection in a closed loop was simulated by using a grid model. From our partial differential equations, a three variables Lorentz like system can be reduced. In stable steady region of main flow, result of the simulation agree with the low order system, very well. In slightly super critical region, result of the grid model shows turbulent stable state in contrast with one of the low order system. In sufficient super critical region, the result shows Lorenz like chaotic reversal of main flow, when special resolution is sufficient. The Lorenz like chaotic reversal of main flow along the loop appeared in rather shrunk parameter region which locates in unstable region of the steady main flow. The chaotic region is surrounded by broad turbulent stable region. On the edge region between chaos and turbulent stable, the behavior has delicate sensitivity for experimental, initial and computational conditions.
著者
宮嵜 武 高橋 直也
出版者
日本流体力学会
雑誌
ながれ : 日本流体力学会誌 (ISSN:02863154)
巻号頁・発行日
vol.21, no.6, pp.503-504, 2002-12-25
被引用文献数
5
著者
及川 正行
出版者
日本流体力学会
雑誌
ながれ : 日本流体力学会誌 (ISSN:02863154)
巻号頁・発行日
vol.31, no.2, pp.195-205, 2012-04-25

本連載では非線形波動,とくにソリトンについて基本的な事柄を解説する.ソリトンは流体力学にも現れるが,物性,宇宙,生物など様々な分野でも現れる.いまやいろいろな分野で基礎的知識あるいは常識となっているから若い人がソリトンを学んでおくのは悪くないであろう.また,ソリトンは1965年に発見され,1970年代前半に急激に理論が発展したが,この新しい学問分野の発展の歴史は大変興味深い.それを垣間見るのも若い人たちにはよい教訓になるかもしれない.さらに,ソリトンは数学の様々な分野に関係しているから,あまり自分には関係ないと思っていた数学の分野に関心を持つ契機になるかもしれない.そのようなことを期待してこの連載をはじめたい.ソリトン理論(数学では可積分系と呼ばれたりする)は広大で多岐にわたるので,全体像を示すのは難しいし,私にできることでもない.そこで,この連載では基本的な事柄にかぎる.最近,我が国では離散系の研究が盛んであるが,離散系は戸田格子などに限定する.モデルはなるべく流体からとることにするが,そうでない場合もある.例えば,戸田格子は流体とは関係ないが重要なので取り上げる.この第1章は主としてソリトンの発見と初期の発展に関係している.第2章以降の予定としては次のようなことを考えている.第2章 双曲型方程式と特性曲線,線形分散波 第3章 KdV方程式 第4章 非線形シュレディンガー方程式 第5章 逆散乱法 第6章 広田の方法 第7章 佐藤理論 第8章 KP方程式の解について-空間2次元の例
著者
李家 賢一
出版者
日本流体力学会
雑誌
ながれ : 日本流体力学会誌 (ISSN:02863154)
巻号頁・発行日
vol.22, no.1, pp.15-22, 2003-02-25
被引用文献数
4
著者
上之 和人
出版者
日本流体力学会
雑誌
ながれ : 日本流体力学会誌 (ISSN:02863154)
巻号頁・発行日
vol.25, no.4, pp.381-389, 2006-08-25
被引用文献数
1

つららの表面を流れ落ちる過冷却状態の薄い水膜からの氷の成長の際に,表面に約1cmのリング状の波模様が現れる.この現象を,自由表面をもつシアー流れのある薄い液膜からの結晶成長過程における固液界面の形態不安定性の問題として扱う.界面の線形安定性解析により,波模様の波長を定量的に求め,波模様形成の新しいメカニズムを提唱する.
著者
嶺 祐太 平原 裕行 蛭ヶ谷 潤
出版者
日本流体力学会
雑誌
日本流体力学会年会講演論文集 (ISSN:13428004)
巻号頁・発行日
vol.2009, 2009-09-02

A laser-induced micro shock wave was observed with shadowgraphic technique. The shock wave was induced on a metal surface by laser irradiation. In this paper, a micro shock wave was introduced in a relatively low intensity energy region. Shadowgraphic images were acquired within 1μs from laser irradiation. The shock Mach number was measured by shadowgraphic images, and it was higher than 5 in 100ns from laser irradiation in present experimental condition. Energy conversion coefficient was estimated by ratio of the shock wave energy to input laser energy. Here, the shock wave energy was estimated by self-similar analysis.