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Horiguchi, Naoki; Yoshida, Hiroyuki; Kaneko, Akiko*; Abe, Yutaka*
Physics of Fluids, 35(7), p.073309_1 - 073309_17, 2023/07
Times Cited Count：0 Percentile：0.01(Mechanics)The atomization of a liquid jet in an immiscible liquid-liquid system is significant for the safety in the nuclear industry field. The Japan Atomic Energy Agency has developed an evaluation method of a melt fuel behavior as a liquid jet in an immiscible liquid-liquid system for subsequence using mechanistic numerical simulation and has investigated liquid jet behavior in a shallow pool through numerical simulations and experiments. The paper clarifies the atomization mechanism in the wall-impinging liquid jet. Herein, the atomization behavior in the wall-impinging liquid jet in a shallow pool in an immiscible liquid-liquid system was studied in terms of droplet formation and flow field using numerical simulation and the dispersed-phase tracking method. The results show that the droplet formation in the liquid film flow of the wall-impinging liquid jet had the three patterns, and we obtained the droplet properties immediately after droplet formation and developed the theoretical criterion regions using the dimensionless numbers for droplet formation. We characterized the patterns by comparing them with the regions and elucidated the droplet formation mechanisms depending on their sources. Moreover, we elucidated that the relationship between droplet formation as the local behaviors of the jet and atomization as the whole behavior.
Yamamura, Sota*; Fujiwara, Kota*; Honda, Kota*; Yoshida, Hiroyuki; Horiguchi, Naoki; Kaneko, Akiko*; Abe, Yutaka*
Physics of Fluids, 34(8), p.082110_1 - 082110_13, 2022/08
Times Cited Count：2 Percentile：37.96(Mechanics)Liquid spreading and atomization due to jet impingement in liquid-liquid systems are considered to be crucial for understanding the cooling behavior of high-temperature molten material in a shallow water pool. This phenomenon takes place when a liquid jet enters a pool filled with other immiscible liquid. The jet spreads radially after impinging on the floor while forming a thin liquid film and atomizing droplets. In this paper, we explain the result to quantify the unsteady three-dimensional behavior of the spreading jet by the employment of 3D-LIF measurements and 3-dimensional reconstruction. Under high flow velocity conditions, the phenomena of hydraulic jump and atomization of the liquid film occurred along with the spreading. To evaluate the spreading behavior, a comparison of the jump radius position of the liquid-liquid system as the representative value was made with the one calculated by the existing theory of a gas-liquid system. As the result, the spreading of the liquid film in the liquid-liquid system was suppressed compared with that in the gas-liquid system. Furthermore, the PTV method was successfully used to measure the velocity boundary layer and velocity profile in the liquid film, which are important factors that affect the spreading mechanism of the liquid film. These results revealed that in liquid-liquid systems, shear stress at the liquid-liquid interface causes a decrease in the flow velocity and suppressed the development of the velocity boundary layer. Also, to evaluate the atomization behavior, the number and diameter distribution of the droplets were measured from the acquired 3-dimensional shape data of the jet. As the result, the number of droplets increased with the flow velocity. Based on these results, we concluded that the spreading of the liquid film is affected by such atomization behavior.
Yabunaka, Shunsuke; Fujitani, Yohei*
Physics of Fluids, 34(5), p.052012_1 - 052012_18, 2022/05
Times Cited Count：2 Percentile：37.96(Mechanics)We study isothermal transport of a binary fluid mixture, which lies in the homogeneous phase near the demixing critical point, through a capillary tube. A short-range interaction is assumed between each mixture component and the tube's wall surface, which usually attracts one component more than the other. The resulting preferential adsorption becomes significant owing to large osmotic susceptibility. The mixture flowing out of the tube is rich in the preferred component when flow is driven by the pressure difference between the reservoirs. When flow is driven by the mass-fraction difference, the total mass flow occurs in the presence of the preferential adsorption. These phenomena can be regarded as cross-effects linked by the reciprocal relation. The latter implies that diffusioosmosis arises from the free energy of the bulk of the mixture not involving the surface potential, unlike usual diffusioosmosis far from the critical point. We also study these phenomena numerically by using the hydrodynamics based on the coarse-grained free-energy functional, which was previously obtained to reveal near-critical static properties, and using material constants that were previously obtained in some experimental studies. Influence of the critical enhancement of the transport coefficients is found to be negligible because of off-critical composition in the tube. It is also shown that the conductance, or the total mass flow rate under a given mass-fraction difference, can change non-monotonically with the temperature. The change is well expected to be large enough to be detected experimentally.
Saito, Shimpei*; De Rosis, A.*; Fei, L.*; Luo, K. H.*; Ebihara, Kenichi; Kaneko, Akiko*; Abe, Yutaka*
Physics of Fluids, 33(2), p.023307_1 - 023307_21, 2021/02
Times Cited Count：34 Percentile：98.3(Mechanics)A Boiling phenomenon in a liquid flow field is known as forced-convection boiling. We numerically investigated the boiling system on a cylinder in a flow at a saturated condition. To deal with such a phenomenon, we developed a numerical scheme based on the pseudopotential lattice Boltzmann method. The collision was performed in the space of central moments (CMs) to enhance stability for high Reynolds numbers. Furthermore, additional terms for thermodynamic consistency were derived in a CMs framework. The effectiveness of the model was tested against some boiling processes, including nucleation, growth, and departure of a vapor bubble for high Reynolds numbers. Our model can reproduce all the boiling regimes without the artificial initial vapor phase. We found that the Nukiyama curve appears even though the focused system is the forced-convection system. Also, our simulations support experimental observations of intermittent direct solid-liquid contact even in the film-boiling regime.
Furuichi, Noriyuki*; Terao, Yoshiya*; Wada, Yuki; Tsuji, Yoshiyuki*
Physics of Fluids, 30(5), p.055101_1 - 055101_7, 2018/05
Times Cited Count：16 Percentile：72.47(Mechanics)Ida, Masato
Physics of Fluids, 21(11), p.113302_1 - 113302_13, 2009/12
Times Cited Count：32 Percentile：72.87(Mechanics)The inception of cavitation in multibubble cases is studied numerically and theoretically to show that it is different from that in single-bubble cases in several aspects. By examining in detail the dynamics of interacting cavitation bubbles, we found that (a) a relatively large bubble can significantly decrease the cavitation threshold pressure of a nearby small bubble and (b) the explosive expansion of a bubble under negative pressure can be interrupted and turn into collapse even though the far-field liquid pressure well exceeds the bubble's threshold pressure. When we extended the discussion to systems of larger numbers of bubbles, we found that (c) a larger number of bubbles decrease the magnitude of the negative pressure of the surrounding liquid by a greater degree. The present findings would be useful in understanding the complex behavior of cavitation bubbles in practical applications where in general many cavitation nuclei exist and may interact with each other.
Satake, Shinichi*; Kunugi, Tomoaki*; Takase, Kazuyuki; Ose, Yasuo*
Physics of Fluids, 18(12), p.125106_1 - 125106_8, 2006/12
Times Cited Count：34 Percentile：73.45(Mechanics)no abstracts in English
Ida, Masato
Physics of Fluids, 17(9), p.097107_1 - 097107_13, 2005/09
Times Cited Count：16 Percentile：52.73(Mechanics)The transition frequencies of multibubble systems in a sound field are reexamined theoretically to confirm their existence and further clarify their physical properties. Via a forced coupled oscillator model, the following results are obtained: (1) further details of the characteristics of the transition frequencies, (2) the theoretical determination of the threshold distances for the appearance of the sub-transition frequencies, (3) a simple understanding of the sign reversal of the interaction force, and (4) the clarification of several similarities and differences among the natural, resonance, and transition frequencies in double-bubble cases. The present effort enforces our claim that transition frequencies causing no resonance response exist in multibubble systems and thoroughly clarifies the physical effects of the transition frequencies and their roles in the sign reversal of the interaction force.
Fukuyama, Atsushi*; Ito, Kimitaka*; Ito, Sanae*; Hamamatsu, Kiyotaka
Physics of Fluids B; Plasma Physics, 5(2), p.539 - 549, 1993/02
Times Cited Count：15 Percentile：49.69(Physics, Fluids & Plasmas)no abstracts in English
