著者

山内 豊

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

vol.27, no.1, pp.11-17, 2013-03-15 (Released:2013-06-05)

参考文献数

11

---

Developments of natural resources in the Arctic region are becoming active in the recent years. Commercial use of the northern sea route is taking on realness with a decrease of sea ice area along the Arctic coast. Also Arctic and Antarctic observation is important to clarify a global climatic change. Icebreakers are indispensable to the support for the development, the escort for cargo ships and the polar observation in ice-covered waters. The technology on icebreaker's performance is improving steadily, responding to those missions. This paper shows the typical characteristics of icebreaker and introduces several technologies to improve the performance.

著者

佐野 寛

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

vol.25, no.1, pp.4-11, 2011-03-15 (Released:2011-06-15)

参考文献数

10

被引用文献数

1

---

A lot of forest-biomass exists on the steep mountain in Japan. However, it is very difficult to obtain the forest-biomass like brushwood, from the deep mountain to human habitation. Using by chute, brushwood can be transported automatically if we can keep an appropriate slope gradient. The most important point is a repose angle of chip on the slope. These angles are strongly depending on the figure of chip, the aspect ratio, and the surface roughness of the chute bed.

著者

佐藤 兼太 川崎 浩司 越村 俊一

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

vol.37, no.3, pp.316-323, 2023-09-15 (Released:2023-10-08)

参考文献数

18

---

Characteristics of tsunami flow in cities are three-dimensional, highly non-linear and non-hydrostatic. A fully three-dimensional free-surface fluid model is required to simulate such a flow field. Fluid simulations in the field of coastal engineering are often large-scale since large areas are the subject of the simulations. The numerical model must be not only accurate but also efficient. In recent years, the lattice Boltzmann method (LBM) has attracted much attention as a novel simulation method and has been successfully applied to various engineering fields. Moreover, the cumulant LBM has attracted attention because it has excellent numerical stability even for high Reynolds number flows. The single-phase free-surface flow model using the cumulant LBM is a suitable approach for simulating violent flow fields in coastal engineering. In this study, we propose a single-phase free-surface flow model based on the cumulant LBM using the volume-of-fluid (VOF) model. We demonstrate that the cumulant LBM is stable under violent flows and reproduces the pressure field well compared with the traditional single relaxation time model. We find that a larger bulk viscosity can reduce the numerical oscillation of the impact pressure acting on a structure, although a bulk viscosity that is too large reduces the accuracy and stability. The results of the proposed model are in good agreement with previous experimental results.

著者

岸本 健治

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

vol.11, no.1, pp.7-10, 1997-03-15 (Released:2011-02-22)

---

Liquid propellant rocket engine is introduced, and discussed about the technology status. As a relation with Multiphase technology, a new rocket engine development approach is introduced.

著者

谷本 潤

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

vol.28, no.3, pp.280-287, 2014-09-15 (Released:2014-11-01)

参考文献数

6

---

This paper overviews how the author's group has been exploring on the decision-making process with social dilemma of individual vaccination, namely whether or not to be vaccinated, by means of the model of dynamics for epidemic spreading on a social network applied to evolutionary game theory. On underlying networks, both epidemic and information of agent's strategy are transferred, where the former is modeled by SIR and the latter is emulated as a spatial evolutionary game. Simulation results imply that both the vaccination acceptance fraction and final epidemic size are significantly affected by how strategy updating happens; namely whether he/ she copying from a neighbor or imitating a social trend, and underlying network topologies. The study poses one example of how the social physics helps to understand complex phenomenon taking place in a real world.

著者

新見 英幸

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

vol.1, no.1, pp.6-17, 1987-09-15 (Released:2011-02-22)

参考文献数

45

---

Blood is a suspension of blood cells in a Newtonian fluid of plasma. The red blood cells (RBCs) are most numerous and behave like small deformable capsules containing a Newtonian fluid. How to treat blood flowing through vessels depends on the scale involved. The flow characteristics of blood in the microvessel with a diameter comparable with the RBC size may be determined by the behavior of individual RBCs, for which a multi-phase flow model may provide a good approximation. Some multiphase flow problems of blood flow are studied.

著者

益山 忠

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

vol.10, no.3, pp.251-254, 1996-09-15 (Released:2011-02-22)

参考文献数

7

---

Since slurry transportation systems are very useful to transport bulk materials, the systems are used in transporting ores and tailings in mining industries and in dredging harbors. This paper describes the characteristics of the slurry transportation systems, and the plan and application of the systems, written as follows, in mineral development in Japan. 1) The plan of Ishikari coal slurry tranport pipeline. 2) The hydraulic transportation system in Sunagawa coal mine. 3) The backfill slurry transportation system in cut-and-fill stoping. 4) The Oodate-Noshiro tailling slurry transport pipeline. 5) The pilot plant system of slurry transportation for sediment sand in Sakuma dam reservoir. 6) The manganese nodule mining system using airlift pump by National Research Institute for Pollution and Resources. 7) The control of gas kick and drilling mud flow in drilling well for methane hydrate production.

著者

佐藤 博

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

vol.14, no.3, pp.280-292, 2000-09-15 (Released:2011-02-22)

参考文献数

25

被引用文献数

1

---

Flow patterns of settling slurry flow in a horizontal pipe can be represented graphically on the pressure drop-flow rate relation at a constant concentration, because the mechanism of pressure drop depends makedly on the flow regimes: stationary bed, sliding bed or moving bed, saltation flow, heterogeneous flow, and pseudo-homogeneous flow. Although it is difficult to clarify the sharp boundaries between these categories, the criterion based on concentration distributions may be one of the most effective parameters that depend on the degree of homogeneity. The main objective of this paper is, therefore, to discuss criteria for determining flow patterns and an analytical method of concentration distributions, introducing an interesting method of displaying solids flow behavior on a monitoring screen.

著者

赤松 重則 上田 義勝

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

vol.36, no.1, pp.20-27, 2022-03-15 (Released:2022-03-31)

参考文献数

21

---

Bubbles with a diameter less than 1μm are called ultrafine bubbles (UFB). And UFB is expected to be applied in the environment, agriculture and medical treatment. In this study, we will examine the possibility by using ultrasonic waves and ultrapure water (UPW), also the attenuation characteristics of UFB water, to analyze the properties of UFB. The attenuation characteristics of UFB water in broadband ultrasound waves up to 32.5 MHz were investigated. In the 1.5-2.5 MHz ultrasonic band, the attenuation coefficient in the near-field was relatively close to the theoretical value calculated from the bubble density measurement results. For the 32.5 MHz ultrasound, there was a clear difference in the attenuation coefficient for the bubble density distribution between the UPW and the UFB water. In addition, the change in the number density distribution of bubbles and the change in the attenuation coefficient were observed depending on the elapsed days after UFB generation. It is possible that the change is related to the increase in the bubble diameter of the UFB.

著者

田中 敏嗣

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

vol.8, no.2, pp.140-146, 1994-06-15 (Released:2011-02-22)

参考文献数

20

---

固気二相流中を運動する粒子が粒子間衝突の影響を受けるような流れをラグランジュ型の数値シミュレーションで取り扱おうとする場合に、希薄気体の流れの計算に用いられるDSMC法 [1] は粒子間衝突の有力な計算法として期待できる。本講座はそのような立場からDSMC法の基礎とその固気二相流への応用について述べるものである。前回 [2] はその1回目として、固気二相流中での粒子間衝突の影響と、DSMC法を理解するために必要な分子気体力学の基礎概念について述べた。今回はそれに引き続いて、DSMC法で用いられるモンテカルロ法の手法とDSMC法について解説を行う。

著者

小林 和也 栗田 玲

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

vol.35, no.1, pp.118-124, 2021-03-15 (Released:2021-04-15)

参考文献数

16

---

Gravitational instability, which is a typical example of hydrodynamic instabilities, occurs due to density difference. When a heavy fluid lies over a light fluid in a constant gravitational field, fluctuations at the interface gradually increase and then macroscopic flows occur. The gravitational instability can be found not only in liquid-liquid interface but also in the gravitational settling of granular materials. However, the gravitational instability of liquid systems and granular systems have been discussed individually in most cases. We quantitatively find a close relationship of the gravitational instability between the physical gel and granular systems. We also find that those behaviors are determined by the thickness of the fluidization region.

著者

佐藤 岳彦 上田 義勝 高橋 克幸 高木 浩一

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

vol.35, no.2, pp.251-258, 2021-06-15 (Released:2021-07-08)

参考文献数

35

被引用文献数

3

---

In this review, inactivation and activation of microorganisms using fine bubbles are introduced. In the first chapter, we introduce domestic and overseas research trends of sterilization methods using ozone and plasma. In the second chapter, we focus on researches such as cleaning of lipstick at cosmetic application, generation of plasma-activated microbubbles for sterilization of fresh foods and verification of underwater plasma characteristics under fine bubble dispersion for improvement of chemical activity of bubbles. The third chapter is an introduction of our activity through International Symposium on Application of High-voltage, Plasma & Micro/Nano Bubble to Agriculture (ISHPMNB).

著者

大谷 清伸 小川 俊広 杉山 勇太 丹波 高裕

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

pp.2021.005, (Released:2021-04-15)

参考文献数

14

---

This paper reports preliminary experimental results of shock wave/ water droplets interaction phenomena related to shock wave pressure attenuation. Water droplets were generated by dropping from a several needle pipes, were interacted with micro-explosive-induced shock wave. The process of induced spherical shock wave/ water droplets interaction phenomena was visualized by shadowgraph method and recorded by a high-speed camera. The pressure histories of propagated shock wave interacting with water droplets were measured simultaneously by using the pressure transducer. High-speed shadowgraph sequential images show that interacted water droplets were highly deformed, and a wave front of a secondary shock wave was decayed. The simultaneously measured pressure history shows that a primary shock wave peak pressure was attenuated with interacting at water droplets, and a peak pressure ratio was decreased.

著者

前田 泰希 金川 哲也

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

vol.34, no.1, pp.140-147, 2020-03-15 (Released:2020-04-02)

参考文献数

20

被引用文献数

2

---

Weakly nonlinear propagation of plane pressure waves in a flowing water uniformlycontaining many spherical microbubbles is theoretically investigated. At the initial state, the gas and liquid phases have different flow velocity distributions as a small nonuniform effect in bubbly flows. The basic equations based on a two-fluid model are utilized to describe velocity distributions of gas and liquid phases. By using the method of multiple scales and the determination of size of three nondimensional ratios, we can systematically derive two types of nonlinear wave equations describing long-range propagation of waves. i.e., the Korteweg-de Vries-Burgers (KdVB) equation and the nonlinear Schrödinger (NLS) equation with variable coefficients. As a result, initial velocity distributions affect an advection effect of waves induced by a relative velocity between gas and liquid phases and a moving bubble.

著者

圷 亮輔 慶本 天謹 金川 哲也 内山 祐介

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

vol.34, no.1, pp.166-179, 2020-03-15 (Released:2020-04-02)

参考文献数

28

---

Two types of weakly nonlinear propagations of plane progressive pressure waves in an initially quiescent compressible liquid uniformly containing many spherical gas bubbles are theoretically investigated. The treatment of two types of propagations corresponds to an extension of our previous result (Yoshimoto & Kanagawa, Jpn. J. Multiphase Flow, 33 (2019), 77) to a generic form. The main assumptions are as follows: (i) The incident wave frequency is much larger than an eigenfrequency of single bubble oscillations; (ii) The compressibility of the liquid phase, which has long been neglected and induces the high speed propagation mode, is considered; (iii) The wave propagates with a large phase velocity exceeding the speed of sound in pure water. From the method of multiple scales with two types of appropriate choices of three nondimensional parameters, we can systematically derive two types of nonlinear Schrödinger (NLS) equations with some correction terms in a unified way. These two equations can describe high-speed propagation of pressure waves in compressible bubbly liquids.

著者

鮎貝 崇広 金川 哲也

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

vol.34, no.1, pp.158-165, 2020-03-15 (Released:2020-04-02)

参考文献数

13

被引用文献数

7

---

Oscillation of gas bubbles in a bubbly liquid induces dissipation and dispersion effectsof waves into a nonlinear evolution of pressure waves. Long-range propagation of pressure waves with a moderately small amplitude is described by the KdV-Burgers (KdVB) equation. This paper numerically solves the KdVB equation via a spectral method to predict the nonlinear evolution of waves in bubbly liquids. Focusing on the waveform, and the nonlinear, dissipation and dispersion terms, the following results are obtained: (i) An initially sinusoidal waveform satisfying a periodic boundary condition is firstly distorted due to the nonlinear effect; (ii) Wave distortion is suppressed by increasing the dissipation and dispersion effects; (iii) A break-up due to the dispersion effect appears; (iv) A balance between the nonlinear and dispersion effects is accomplished and then a pulse wave satisfying a feature of soliton is formed. As a result, the initial bubble radius and the initial void fraction strongly contribute the dissipation and dispersion effects, respectively.

著者

亀井 陸史 金川 哲也

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

vol.34, no.1, pp.148-157, 2020-03-15 (Released:2020-04-02)

参考文献数

20

被引用文献数

2

---

This study theoretically clarifies an effect of the liquid viscosity and the thermal conductivity on weakly nonlinear propagation of pressure waves in a liquid containing many spherical microbubbles. As in our preceding paper (Kamei et al., J. JSCE, Ser. A2, 75 (2019), 499) focusing on a long wave, by the use of the method of multiple scales, a nonlinear Schrödinger equation describing the long-range propagation of an envelope wave of short carrier wave is derived from the basic equations incorporating the liquid viscosity and the thermal conductivity. As a result, as in our preceding long wave case, the liquid viscosity and the thermal conductivity affect the dissipation effect, and a nonlinear effect in the adiabatic process decreases in comparison with the previous study (Kanagawa et al., J. Fluid Sci. Technol., 6 (2011), 838). On the other hand, unlike in our preceding long wave case, a dispersion effect in the adiabatic process decreases in comparison with the previous study.

著者

伊藤 啓 伊藤 大介 齊藤 泰司 松下 健太郎 江連 俊樹 田中 正暁

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

vol.34, no.1, pp.118-124, 2020-03-15 (Released:2020-04-02)

参考文献数

11

被引用文献数

1

---

In the design study on sodium-cooled fast reactors, .it is important to investigate the gas entrainment (GE) phenomena in detail. In fact, a lot of analytical, experimental and numerical studies have been conducted to clarify the onset condition of GE and some GE onset models have been proposed. However, few studies on the modeling of entrained gas flow rate has been conducted due to the difficulty on modeling the gas bubble entrainment at a free surface, which is accompanied by complicated free surface deformation. In this paper, the authors propose a mechanistic model to predict the entrained gas flow rate by a free surface vortex. The model contains the theoretical equation of transient gas core elongation and the empirical equation of critical gas core length for gas bubble detachment. The mechanistic model is applied to predict the entrained gas flow rate in a simple GE experiment. As a result, the predicted results show qualitatively good agreement with the experimental results of the entrained gas flow rate. Therefore, it is confirmed that the proposed mechanistic model can predict the entrained gas flow rate by a free surface vortex.

著者

渡辺 勢也 青木 尊之 長谷川 雄太 河原 淳 橋本 博公

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

vol.33, no.1, pp.55-62, 2019-03-15 (Released:2019-04-08)

参考文献数

21

被引用文献数

1

---

Numerical simulations are powerful tools to study tsunami impacts on building structures. We have developed a CFD code for free-surface flows interacting with floating debris by using Lattice Boltzmann Method (LBM) and Discrete Element Method (DEM). Both methods are suitable for GPU computing and large-scale simulations because they are explicit time-integration schemes. In order to improve the accuracy and the stability of flow computation, the cumulant LBM model has been employed and coupled with the conservative Allen-Cahn equation for the purpose of free-surface capturing. A moving boundary approach based on the interpolated bounce-back scheme is utilized at liquid-solid interfaces. Rigid body dynamics of floating debris is computed by using DEM. A model constructed by multiple small spheres represents complex shapes of debris. We measure the weak scalability on multiple GPUs of the TSUBAME3.0 supercomputer, and the code achieved 83.4% parallel efficiency when scaled 16 to 256 GPUs. As a test case, we demonstrate a tsunami flow with driftwoods using 200×600×3000 lattice nodes and 24 GPUs Tesla P100, and the simulation has completed within 24 hours. The impact force of the driftwoods acting on the wall is about 15 times larger than only water. It shows that effects of driftwoods are important to evaluate the tsunami damage on building structures.

著者

山口 拓真 師岡 愼一

出版者

日本混相流学会

雑誌

混相流 (ISSN:09142843)

巻号頁・発行日

pp.2018.004, (Released:2018-05-18)

参考文献数

15

被引用文献数

2

---

The severe accident in Fukushima daiichi nuclear power plant revealed the importance of molten core cooling system without the electric power, then cooling system by natural circulation flow has attracted attention. The heat removal performance of this system depends on the natural circulation flow rate, so it is essential to predict the flow rate accurately for the safety design. The purpose of this study is to develop the evaluation method for the natural circulation, and to examine its accuracy dependence on the channel shape. Experiments were carried out at atmospheric pressure, using room temperature air-water flow. We used seven kinds of channels with various shape and diameter, and measured natural circulation flow rate and pressure drop for each channel. Predictive analysis was conducted by our method based on balance between driving force and pressure drop in the loop channel. The major results are as follows: (1) It is possible to predict the natural circulation flow rate with an error of less than 20 percent for various shaped channels. The average and standard deviation for the ratio between calculated and experimental flow rate is 0.98 and 0.047. (2) Two phase prediction method for pressure drop has maximum 15 % error. To improve the prediction accuracy, it is important to improve the prediction of the void fraction and the two-phase multiplier.