論文発表
K. Kuwagi, T. Fukui, A. Kogane and H. Hirano, Relationship between dimensionless buoyancy and pressure drop fluctuation under fluidization conditions, Proc. The 29th International Symposium on Transport Phenomena (ISTP29), pp.1-4 (USB), Paper No.62, 30 October - 2 November, 2018, Honolulu, USA
西山真由，平井貴大，平野博之, 凹凸型マイクロ流路内における交互流の数値解析, 岡山理科大学紀要，第54号A, pp.59-65, (2019)
Tomohiko Kihara, Hideaki Obata , Hiroyuki Hirano, Quantitative visualization of fluid mixing in slug flow for arbitrary wall-shaped microchannel using Shannon entropy, Chemical Engineering Science, 200, pp.225-235, (2019)
Micro-reactors based on slug flow are among the most promising developments for improving the efficiencies of chemical reactions and unit operations in chemical engineering. Quantitative understanding of the local and global fluid dynamics and their effects on fluid mixing is required for designing effective slug flow micro-reactors. This paper proposes a new method for quantitative two-dimensional assessment of fluid mixing in slug flow. Pixel-wise calculation of local entropy inside a slug is discussed. The proposed method is based on two-phase simulation using the volume of fraction (VOF) algorithm and is thus applicable to the flow pattern in arbitrary wall-shaped micro-reactors. The method consists of three steps. (1) Flow analysis using two-phase VOF algorithm: A series of two-dimensional velocity fields inside the slug along time is obtained for a certain duration. (2) Backward particle tracking from the target image to the initial image: The slug in the initial image is divided into small regions, and each region is assigned a different label. Accumulation of backward particle tracking results reveals a two-dimensional distribution of labels in the target image. (3) Pixel-wise calculation of entropy on the obtained distribution of labels: The resulting image is a quantitative two-dimensional mixing pattern inside the slug. The proposed method was applied to three types of microchannels with different bumps on the walls. The results could quantitatively distinguish the differences in fluid mixing capability among the systems.
Atsuto Kogane, Kenya Kuwagi and Hiroyuki Hirano, Dimensionless parameter for distinction between homogeneous and bubbling fluidization regimes, Advances and Applications in Fluid Mechanics, 23(1), pp.69 – 96, (2019)
When the particle phase is dense, two fluidization regimes can be defined, i.e., homogeneous and bubbling fluidization. In this study, two approaches, i.e., the particle-scale flow analysis and dimensional analysis, were applied to study the mechanism of transition between homogeneous and bubbling fluidization regimes. The fluidization behaviors were simulated using the discrete element method and the computational fluid dynamics (DEM-CFD) coupling model. The findings reveal that the bubbling and homogeneous regimes were almost divided into two separate regions when the lateral force was plotted against the Archimedes number (Ar) and Reynolds number (Re). The boundary plane that separated the homogenous and bubbling regions was expressed as a function of (Re/Ar). Within the Stokes flow region, (Re/Ar) can be expressed by the dimensionless drag force and buoyancy. The results of plotting the dimensionless gravity term against Re revealed that the dimensionless gravity term: distinguishes between the two states of fluidization.
K. Kuwagi, A. Kogane and H. Hirano, Comparison of estimation equation obtained from dimensionless gravity term with prior equations to distinguish between homogeneous and bubbling fluidizations, Proc. of The 30th International Symposium on Transport Phenomena (ISTP30), pp.578-584, 1-3 November, 2019, Halong, Vietnam.
西山真由，平野博之, 菱形マイクロ流路内における交互流を利用した物質移動, 岡山理科大学紀要，第55号A, pp.55-59, (2019)
Kenya Kuwagi, Atsuto Kogane, Yui Sasaki, Hiroyuki Hirano, Validation of Dimensionless Parameters for Distinguishing between Homogeneous and Bubbling Fluidizations, Open Journal of Fluid Dynamics, 11, 81-97, (2021)
The difference between homogeneous and bubbling fluidization behaviors has been studied for the past 70 years, where several researchers have reported on the influence of interparticle forces in fluidization. Although inter-
particle forces such as van der Waals forces are evident in a real system, these forces are not the determinant in homogeneous fluidization, which can be simulated without any interparticle forces. In our previous study, the difference in fundamental mechanisms of the two fluidization states was analytically determined with a dimensionless gravity term, comprising the Reynolds number, Archimedes number, and density ratio. Nevertheless, some researchers insist that interparticle forces are dominant and a hydrodynamic force is not dominant. In this study, a dimensional analysis was applied to obtain a dominant parameter for distinguishing two fluidizations. Furthermore, some parameters were examined by comparing the experimental data in previous studies. The results indicated that hydrodynamic force is the dominant factor and the dimensionless gravity term is the dominant parameter in differentiating the two fluidized states.
Hiroyuki Hirano, ShogoTsuzaki, HideakiObata, Tomohiko Kihara, A colorimetric method for quantitative visualization of diffusion and internal circulation in liquid-liquid two-phase flow, Chemical Engineering Science, Chem. Eng. Sci., 249, (2022).
Herein, we propose a new method for the quantitative evaluation of mass-transfer characteristics in liquid–liquid two-phase flow during the formation of slug and its progression in a microchannel. The experimental setup included a 0.3-mm square microchannel with a Y junction. Distilled water with pH indicator and cyclohexane containing acetic acid were selected as the probe fluids. The acetic-acid concentrations were 0.05 and 0.1 vol%, while the volumetric velocity of the aqueous and organic phases was 0.03 mL/min. Acetic-acid diffusion and its internal circulation in the aqueous slug were visualized by color changes and recorded as microscopically magnified video images. By adopting a deep-learning algorithm, the aqueous slugs were segmented, and a calibration method converted color information to acetic-acid concentration values. The experimental results were comparable with those of previous studies. The presented method also revealed several new features that could not have been observed quantitatively by established experimental methods.
受賞
論文審査貢献賞，公益社団法人化学工学会，2014年，2015年
学会発表
井上 啓, 加藤暢恵, 平野博之, カオス尺度を用いた気液二相流モデルの解析, 日本応用数理学会2017年度年会講演予稿集, pp.209-210, 6-8 Sep., 2017, 東京.
熊本翔乃, 山本萌絵, 平野博之, OpenFOAMによる減圧下における立方体容器内の自然対流の数値計算, オープンCAEシンポジウム2017@名古屋 講演会 講演概要集, C13, 8-9 Dec., 2017, 名古屋.
西山真由, 平井貴大, 平野博之, 木原朝彦, 野村悦治, OpenFOAMによる壁面に凹凸を有するマイクロ流路内の液々二相交互流の数値解析, オープンCAEシンポジウム2017@名古屋 講演会 講演概要集, C16, 8-9 Dec., 2017, 名古屋.
井上 啓, 加藤暢恵, 平野博之, 水槽内に生じる気液二相流シミュレーションデータのカオス尺度による解析, 日本応用数理学会 環瀬戸内応用数理研究部会 第21回シンポジウム講演予稿集, pp.28-31, 6-7 Jan., 2018, 松江.
西山真由，平井貴大，平野博之，木原朝彦，小畑秀明, 壁面に凹凸を有するマイクロ流路内の液々二相交互流の可視化と数値解析, 第55回化学関連支部合同九州大会講演予稿集, p.89, 30 Jun. 2018, 北九州.
西山真由，平野博之，木原朝彦，小畑秀明，桑木賢也, マイクロ流路内における液々二相交互流を利用した物質移動, 第56回化学関連支部合同九州大会講演予稿集, p.53, 13 Jul. 2019, 北九州.
桑木賢也，小金篤人，平野博之, 流動化現象に対する次元解析の適用性の検討, 第57回粉体に関する討論会講演論文集, pp.134-138, 25-27 Nov. 2019, 広島.
桑木賢也, 小金篤人, 平野博之, 振動粉体層内の平均粒子速度に及ぼす容器サイズの影響, 第24回日本流体力学会 中四国・九州支部講演会演要旨集, USB pp.1-2, 30 Nov. - 1 Dec., 2019, 松山.
桑木賢也, 福岡誠也，平野博之, 車輪下の砂粒子の運動の数値シミュレーション, オープンCAE・FrontISTR合同シンポジウム2020 梗概集, A-9, 4-5 Dec., 2020, オンライン.
平野博之，木原朝彦，パク ボソン（朴 報聖），津崎翔悟，串田尚樹，小畑秀明，桑木賢也, マイクロ流路内で生じる液－液二相交互流の数値解析とシャノン・エントロピーによる物質移動評価, 環瀬戸内応用数理研究部会第24回シンポジウム講演予稿集（研究会資料）, pp.1-4, 12-13 Dec. 2020, 岡山市 岡山理科大学.
佐々木友惟, 桑木賢也, 平野博之, DEMシミュレーションで麺生地を表現するための粒子間付着力の検討, 第23回化学工学会学生発表会要旨集, B14, 6 Mar., 2021, オンライン.
佐々木友惟, 桑木賢也, 平野博之, 麺生地混練過程の粉体のDEMシミュレーョン, オープンCAEシンポジウム2021 梗概集, A-16, 2-4 Dec., 2021, オンライン.
佐々木友惟, 桑木賢也, 平野博之, LIGGGHTS 較を用いた麺生地混錬過程の粉体数値シミュレーション, 2022 年度第 29 回日本流体力学会中四国・九州支部総会講演会 論文集, 1-2, 28 May, 2022, 福岡大学.