著者

斎藤 崇雄 中村 哲也 メンショフ・イゴール 中村 佳朗 前田 一郎 内山 直樹 海田 武司

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.2003, pp.480-481, 2003-07-28

被引用文献数

1

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The phenomena of ignition overpressure (IOP) has been simulated in two cases with the specific heat ratio γ=1.18 and γ=1.4. The former case assumes that a combustion gas fills the overall computational region, while the latter assumes air instead of the combustion gas. The objective of the present study is to investigate whether IOP is affected by the kind of gas. This simulation was performed for a solid rocket booster (SRB) of space shuttle. The time history of pressure rise at the nozzle inlet was taken into account by imitating the SRB ignition. The result with γ=1.18 shows good agreement with the data measured on the surface of STS-Ts SRB.

著者

竹村 早紀 佐々 浩司

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

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We simulated supercell type tornadoes with our newly designed mesocyclone simulator and a wall jet generator. The fluctuating velocity of the tornado is measured near the floor by using an X-probe and hotwire anemometers. Its spectrum showed that the velocity field at the lower layer of the tornado was highly turbulent. Its peak corresponds to the existence of suction vortices in multiple vortex type tornado.

著者

山崎 麻未 濱田 一平 佐々 浩司

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.2010, 2010-09-09

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Our mesocyclone simulator was improved to reduce the effect of separation flow generated from guide vanes. The arrangement between the mesocylone simulator and the gust generator was also changed. The results of flow visualization showed that four different flow patterns occurred depending upon swirl ratio and height.

著者

原 由紀男 中西 幹郎 小林 文明

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 (ISSN:13428004)

巻号頁・発行日

vol.2001, pp.47-48, 2001-07-31

参考文献数

1

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In order to examine the generation mechanism of a cumulonimbus that caused a heavy rain in Tokyo urban area on 22 July 1999,three numerical experiments are performed with a mesoscale simulation model; Case 1 (control run) refers to a nearly realistic experiment, Case 2 an experiment without urban effects, and Case 3 an experiment without raindrop evaporating effects. Although Cases 2 and 3 show slightly different distributions of wind and cloud from what are simulated for Case 1,all the cases reproduce clouds that occurred over Tokyo urban area. This may suggest that the main source generating clouds over Tokyo urban area lies in other effects, e.g., the convergence of sea breezes from Tokyo Bay and Sagami Bay.

著者

斎藤 貴之 台坂 博 出田 誠 岡本 崇 小久保 英一郎 和田 桂一 富阪 幸治 牧野 淳一郎 吉田 直紀

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.2006, 2006-09-05

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In this paper, we introduce Project "Origin of the Milkyway". This project aims at reliable modeling of the formation history of our Galaxy (i.e., the Milkyway), as a typical spiral galaxy, with the mass resolution 2-3 orders of magnitude higher than what has been achieved so far. In order to achieve such state-of-the-art simulations, we construct two beowulf type PC-clusters with GRAPE-6A/7, and we develop a new N-body/SPH code for parallel computing.

著者

佐藤 潤一 澤田 恵介 松山 新吾 大西 直文

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.2003, pp.114-115, 2003-07-28

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Three-dimensional numerical simulations of an accretion disc in a close binary system were performed by solving the Euler equations with radiative transfer. We used the one-dimensional (tangent-slab) approximation to calculate the radiative transfer for the vertical directions of the disc. The cooling effect of the disc is considered by discharging energy in only this directions. The influence of radiative cooling has been accounted for by assuming a specific heat ratio γ which is smaller than that of a mono-atomic gas (=5/3). In the present study, the specific heat ratio was assumed to be constant while radiative cooling effect was included as the non-adiabatic process. Our numerical simulations with radiative transfer demonstrated that spiral shocks existed in three-dimensional disc. It was found that its feature approached in the case of a lower γ but its tendency was weaker than that of two-dimensional simulation.

著者

早崎 公威 岡崎 敦男

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.2003, pp.112-113, 2003-07-28

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We study the accretion onto the neutron star in Be/X-ray binaries, using the 3D SPH code and the data from the simulations by Okazaki et al. (2002) for a coplanar system with a short period (P_<orb>=24.3 days) and moderate eccentricity (e=0.34). We find that a non-steady accretion disk is formed around the neutron star. The disk shrinks after the periastron passage of the Be star and restores its radius afterwards. While the mass-capture rate by the neutron star has a regular, strong dependence on the orbital phase, the orbital modulation in the accretion rate slowly gradually decreases. Our simulations show that the truncated Be disk model for Be/X-ray binaries is consistent with the observed X-ray behavior.

著者

長江 滝三 松田 卓也 藤原 秀和 蜂巣 泉 Boffin H. M. J.

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.2002, pp.124-125, 2002-07-23

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Three-dimensional hydrodynamic calculations are performed in order to investigate mass transfer in a close binary system, in which one component undergoes mass loss through a wind. The mass ratio is assumed to be unity. The radius of the mass-losing star is taken to be about a quarter of the separation of the two stars. Calculations are performed for gases with a ratio of specific heatsγ=1.01 and 5/3. Mass loss is assumed to be thermally driven so that the other parameter is the sound speed of the gas on the mass-losing star. Here, we focus our attention to two features : flow patterns and mass accretion ratio, which we define as the ratio of the mass accretion rate onto the companion, M_<acc>, to the mass loss rate from the mass-losing primary star, M_<loss>. We characterize flows by the mean normal velocity of wind on the critical Roche surface of the mass-losing star, V_R. When V_R < 0.4AΩ, where A and Ω are the separation of two stars and the rotational frequency of the binary, respectively, we obtain Roche-lobe over-flow (RLOF), while for V_R > 0.7AΩ we observe wind accretion. We find very complex flow patterns in between these two extreme cases. We derive an empirical formula of the mass accretion ratio as 0.45×10^<-1.8V_R/AΩ> in the low velocity regime and 5.0×10^<-3> (V_R/AΩ)^<-4> in the high velocity regime.

著者

國眼 陽子 望月 修

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.2003, pp.208-209, 2003-07-28

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A motion of an ameba moving by crawling over a surface was investigated in order to apply it to a micro soft robot. An ameba was observed by using a high-powered microscope. For cytoplasmic streaming in ameba, granular materials with a diameter of 1.5μm in ameba were traced by a micro PTV measurement instead of injection of micro partices. Change in velocity vector distribution in ameba was obtained in every 1/30 second. Ratios of influx to efflux of several parts in ameba were estimated. Maximum velocity of cytoplasmic flowing into a stretching pseudopodia was found to be 4 times larger than the stretching speed. Cytoplasmic flow rates of inflow and outflow in the all tested parts were unbalanced.