JAPANESE JOURNAL OF MULTIPHASE FLOW
Online ISSN : 1881-5790
Print ISSN : 0914-2843
ISSN-L : 0914-2843
Volume 29 , Issue 4
Showing 1-9 articles out of 9 articles from the selected issue
Special Issue: Separation and Mixing Technology in Multiphase Flow(2)
Papers:
  • Yoshihiko HIBI, Akira TOMIGASHI
    2015 Volume 29 Issue 4 Pages 326-334
    Published: December 15, 2015
    Released: January 10, 2016
    JOURNALS FREE ACCESS
    The aim of this study is to evaluate a saturation formula of flow in porous media and to integrate the saturation formula into an Atmosphere (gas) - surface water two phase-flow system. It was clear that a distribution of water saturation obtained by the saturation formula of flow in porous media was consistent with that obtained by pressure formulas with modified Picard method when only a porous medium with a bank was simulated by these formulas. Numerical simulation method with the saturation formula for a system coupling atmosphere, surface water and porous media could reproduce flow of the surface water overflowing a bank made of a porous medium and the variation in the water saturation in the bank. As a result, it was confirmed that gas pressure in the bank rose from 0.4 kPa to 5 - 8 kPa when water overflowed the bank and there was partially unsaturated zone in the bank. It is generally known that this phenomenon occurs when gas in porous media cannot escape outside. Therefore the numerical simulation method with the saturation formula of flow in porous media can simulate the system coupling atmosphere, surface water and porous media with unsaturated zone.
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  • Hajime ONUKI, Yoshiyuki TAGAWA
    2015 Volume 29 Issue 4 Pages 335-342
    Published: December 15, 2015
    Released: January 10, 2016
    JOURNALS FREE ACCESS
    A liquid jet is used in various important devices, such as ink-jet printers. However, it is challenging to create a viscous liquid jet using existing methods. In this paper we propose a novel device for generating highly-viscous liquid jets and present a physical model based on pressure impulse approach for explaining its mechanism. We verify the performance of our device experimentally and find that our method can generate a jet of an extremely highly-viscous liquid (1,000 mm2/s). The proposed physical model turns out to be able to describe all experimental results obtained in this research.
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  • Kenichi KATONO, Hayato TAMARU, Shigeo HOSOKAWA, Kosuke HAYASHI, Akio T ...
    2015 Volume 29 Issue 4 Pages 343-350
    Published: December 15, 2015
    Released: January 10, 2016
    JOURNALS FREE ACCESS
    A downscaled model of a steam separator is used to understand characteristics of swirling flow and to investigate the effects of geometry of separator components on separation performance. Main conclusions obtained are as follows. (1) Separation performance improves with the gas volume flux. However carryunder, i.e. the weight percentage of entrained gas in the water leaving the separator, tends to be lower as the liquid film thickness becomes thinner under low liquid volume flux conditions. (2) The ratio of the flow rate of separated liquid to the total liquid flow rate does not depend on the liquid volume flux so much. On the other hand, the carryunder becomes lower with the liquid volume flux. (3) An improved pick-off ring, whose gap width is about the maximum liquid film thickness and sudden expansion is mitigated by a diffuser, effectively reduces the pressure drop while keeping high separation performance.
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  • Hideki TOKANAI, Tomohiro TSUJI, Masafumi KURIYAMA
    2015 Volume 29 Issue 4 Pages 351-355
    Published: December 15, 2015
    Released: January 10, 2016
    JOURNALS FREE ACCESS
    A new apparatus of spouted-bed is proposed, which has a biconical device in fluid inlet. The device is shown to enhance particle-dispersion in the apparatus by controlling the fluid-blowout. Dispersion experiments are carried out using several kinds of solid particles in water flowing at various velocities to obtain the variation in the height of particle-bed with some operating conditions. It is shown that the height increases with increasing both the water velocity and the particle amount but decreases with increasing the particle size and density. By the consideration of such tendencies, a correlation equation is proposed, which expresses the height with water superficial-velocity, particle volume-fraction and particle terminal-settling-velocity.
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  • Yusaku NAGATA, Ichiro KUMAGAI, Anna KUWANA
    2015 Volume 29 Issue 4 Pages 356-363
    Published: December 15, 2015
    Released: January 10, 2016
    JOURNALS FREE ACCESS
    We have explored numerical experiments on the collective motion of Fluidic auto-propulsive particles (Flappers) moving on a circular orbit in a horizontal plane. As a Flapper in this study, the Vortex-Pair Object (VPO) model was adopted. The VPO consists of a vortex pair with a fixed center distance, and moves on a circular orbit if it travels alone. The experimental result on the interaction between two VPOs showed that the collective motion depended on the initial angle between two VPOs; their interactive behaviors were classified by 4 modes in terms of the displacement of their orbits. We also demonstrated the collective motion of 10 VPOs on the circular orbit. The fluidic interaction by the VPOs coupled with a simple BOID rule causes the linear alignment of the VPOs, which are frequently observed in the linear flight formation of migratory birds.
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