Representative Velocity Scale of Rayleigh-Bénard Convection with Shear-Thinning Fluids

The Canadian Journal of Chemical Engineering


An Improved Coupled Level Set and Continuous Moment-of-Fluid Method for Simulating Multiphase Flows with Phase Change

Communications on Applied Mathematics and Computation


Improvement of a Simple Coupled VOF with LS (S- CLSVOF) Method

Journal of Chemical Engineering of Japan


Numerical Simulations of Carreau-model Fluid Flows Past a Circular Cylinder

Asia-Pacific Journal of Chemical Engineering


Application of a Level-Set Method for Deposition of Fine Particles on a Filter

Level Set 法を用いたフィルター上の微粒子積層解析

Level Set法を用いて微粒子の堆積過程による流路変形をともなった流れを計算するために，微粒子の積層により時間的に変化するLevel Set関数ϕの再初期化法の改良を検討した．まず，ϕ=0の非物理的な変形を回避するために適切な再初期化法を選択する必要性を示した．時間にともなうϕの増加(Δϕ)を考慮した場合，再初期化がΔϕに干渉して1ステップ当たりのϕの正味増加量に影響する場合があり，増加後のϕ情報を活用した新たな再初期化法を提案した．本手法によって微粒子が基材に堆積する流れの多次元計算が可能である．


A Three-Dimensional Numerical Study on the Dynamics and Deformation of a Bubble Rising in a Hybrid Carreau and FENE-CR Modeled Polymeric Liquid

Journal of Non-Newtonian Fluid Mechanics


高粘性な粘弾性流体中を上昇する気泡の気液界面から発現する糸状形状に関する考察

高粘性な粘弾性流体中を上昇する気泡の気液界面から発現する糸状形状に関する考察


Prediction of Onset of Taylor-Couette Instability for Shear-thinning Fluids


Three-Dimensional Numerical Analysis of the Filling Process of Milk into Paper Milk Cartons

牛乳紙容器への牛乳充填プロセスの三次元数値解析

Three-dimensional numerical simulations of the flow dynamics of milk using a volume-of-fluid (VOF) method were carried out in order to optimize the process in which milk is filled into a gable top carton with a volume of 1,000 mL. In the numerical simulations, the shear-thinning property of milk was modeled with the Carreau-Yasuda model. The sensitivity of the milk flow dynamics due to the prescribed lifting motion of the gable top carton and due to the filling speed (the number of milk cartons filled per hour) was investigated. When there was no prescribed lifting motion, it was computationally shown that milk which impinged on the bottom of the carton largely jumped and flowed outside the carton. In other words, it was found that a prescribed lifting motion can significantly reduce the amount of milk that escapes the carton. Also, it was found that the efficiency for filling a milk carton was sensitive to the filling speed. The optimum filling speed determined from fully three-dimensional numerical simulations was found to be consistent with previous investigations that used two-dimensional numerical simulations.


The Effect of Filling Operation Conditions on the Efficiency of Production Process of Paper Carton Milk

紙容器入り牛乳の製造プロセスへの充填操作条件の影響

In order to raise the efficiency of the filling process of milk into 1000-mL gable-top cartons, the effect of filling operation conditions on flow dynamics of milk were computationally considered using the Volume-of-Fluid (VOF) method. In the numerical simulation, the shear-thinning property of milk was modeled with the CarreauYasuda model, and the effects of the lifting operation of the gable top carton and filling speed (the number of milk cartons filled per hour) on the flow dynamics of the milk were examined. It was shown by computation that, without the lifting operation, milk that struck the bottom of the carton largely splashed up and out the carton. The lifting of the carton reduces the height of the splash. To examine the effect of the filling speed, one faster and one slower speed than the standard (current empirically selected) operating speed were considered. It was found that the standard speed is appropriate for the present production process.

1,000 mL屋根型紙容器へ牛乳を充填するプロセスの高効率化を実現するために，充填条件が牛乳充填時の流動ダイナミクスに与える影響についてVolume-of-Fluid(VOF)法による2次元数値解析により考察した．数値解析では，牛乳の粘度特性をCarreau–Yasudaモデルによりモデル化し，紙容器の押上げ動作と充填能力(単位時間当たりの充填本数)が流動ダイナミクスへおよぼす影響を調べた．紙容器の押上げ動作の効果に関しては，押上げ動作がない場合は，紙容器底面に衝突した牛乳が大きく跳ね上がり，牛乳が紙容器から容器外部へ流出することがわかった．紙容器の押上げ動作は牛乳の跳ね上がりを抑制する効果があることを確認した．充填能力を経験的に選定されてきた標準操作条件よりも高くした場合と低くした場合の解析より，充填開始時の液跳ねと充填終了時の気液界面の乱れはトレードオフの関係にあることがわかった．紙容器トップシール面への充填液の付着を防止する観点からすると，現在使用されている充填・押上動作曲線に対しては，標準操作条件が適切な充填能力であることを確認した．


Numerical Analysis of the Flow of Fluids with Complex Rheological Properties in a Couette-Taylor Flow Reactor


The Motion of a Bubble Rising through Viscoelastic Polymeric Liquids

粘弾性特性を有する高分子溶液中を上昇する単一気泡の運動特性


The Dynamic Motion of Single Bubbles with Unique Shapes Rising Freely in Hydrophobically Modified Alkali-Soluble Emulsion Polymer Solutions


Numerical Analysis of Flow Dynamics of Milk in a Milk-Filling Process

牛乳充填過程における牛乳の流動ダイナミクスの数値解析

Numerical simulations of flow dynamics of milk using a volume-of-fluid (VOF) method were carried out to understand detailed fluid mechanics of milk in a process in which milk was filled into a gable-top carton with the volume of 1000 mL. All physical properties of milk were measured, and it was verified that in its rheological properties, milk was a purely viscous non-Newtonian fluid with shear-thinning property. In the numerical simulation, the shear-thinning property of milk was modeled with the Carreau-Yasuda model, in which the operating condition for the milk-filling process was set as the computational condition. The numerical results showed that the viscosity of milk was drastically changed in the milk-filling process and that a complicated viscosity profile was formed inside the carton. By comparing numerical results of milk with those of Newtonian fluids, the characteristics of the flow dynamics of milk were more visible. Consequently, it was revealed that the shear-thinning property of milk largely influenced fluid flows inside the carton. Hence, the shear-thinning property of milk cannot be ignored in milk-flow simulations. Numerical analysis will be a useful tool for understanding local changes in the shear-thinning viscosity.

1000 mL屋根型紙容器へ牛乳を充填する過程における詳細な流動メカニズムを把握するために，Volume-of-Fluid(VOF)法による2次元数値解析を行った．本研究では，牛乳の流体物性を実測し，牛乳の流動挙動を解明するうえで重要な知見であるレオロジー特性について，牛乳はShear-thinning性を持つ純粘性非ニュートン流体であることを確認した．数値解析では，牛乳の粘度特性をCarreu–Yasudaモデルによりモデル化し，牛乳の充填過程の流動操作条件を解析条件に忠実に反映させた．解析結果から，牛乳の充填過程において牛乳の粘度は局所的に大きく変化し，紙容器内では複雑な粘度分布が形成されることがわかった．これにより牛乳の有するShear-thinning性が流動現象に大きく影響を及ぼすことが明らかになった．また，ニュートン流体を仮定した解析結果との比較により，牛乳の流動挙動の特徴をより明白に示すとともに，その相違を議論した．牛乳の流動現象評価を行ううえで，Shear-thinning性を無視することができず，局所変化するShear-thinning性を把握するためには，数値解析評価が有用となることが示された．


Influence of the Viscosity Ratio on Drop Dynamics and Breakup for a Drop Rising in an Immiscible Low-Viscous Liquid


A Coupled Level Set-Moment of Fluid Method for Incompressible Two-Phase Flows


The Buoyancy-Driven Motion of a Single Skirted Bubble or Drop Rising through a Viscous Liquid


Numerical Simulations of a Bubble Rising through a Shear-Thickening Fluid

The dynamic motion of a bubble rising through a shear-thickening fluid is numerically simulated. The simulations are carried out on a three-dimensional, dynamic, block-structured adaptive grid. The deforming bubble boundary is captured using the coupled level-set/volume-of-fluid (CLSVOF) method, which combines some of the advantages of the volume-of-fluid (VOF) method with those of the level-set (LS) method. The viscosity profile around the rising bubble is derived from numerical data, and it facilitates the determination of the shear-thickening effects as a function of the power-law exponent n. In general, as n increases, the bubble rise speed decreases and the amount of deformation of the bubble shape decreases. For different values of n, the effective viscosity and the associated effective physical dimensionless numbers are determined in order to quantify the shear-thickening effect of the continuous phase fluid on the bubble rise motion. One can analyze non-Newtonian bubble morphology by considering a non-Newtonian system with a specific effective viscosity.

Journal of Chemical Engineering of Japan


The Dynamic Motion of Single Drops Rising in Countercurrent Linear Shear Flows


Numerical Analysis of Gas-Liquid Bubble Flow in a Horizontal Rectangular Channel


Behavior of Neogene, Soft Sedimentary Rock in the Widening of an Existing Tunnel

新第三紀体積軟岩における既設トンネルの拡幅事例にみる岩盤挙動について


Robust Numerical Analysis of the Dynamic Bubble Formation Process in a Viscous Liquid

International Journal of Multiphase Flow


Lattice Boltzmann Simulations of Viscoplastic Fluid Flows through Complex Flow Channels

Journal of Non-Newtonian Fluid Mechanics


Non-catalytic reduction of nitrogen monoxide by addition of kerosene

ケロシン添加による一酸化窒素の無触媒還元反応

Journal of the Japan Institute of Energy


Size Distribution Measurement of Floating Spherical Particles by the Buoyancy Weighing-Bar Method

浮力秤量法による浮上性球形粒子の粒径分布測定

The particle size distribution of floating spherical solid particles was measured using the buoyancy weighing-bar method. Systems of soda lime silicate glass beads (JIS Test Powders 2, GBL100) in sodium polytungstate solution and hollow glass beads (Glassbubbles K1, S60HS) in water were experimentally investigated. The particle size distribution obtained in our experiments agreed with the particle size measured by laser scattering/diffraction and by microscopic observation. The present study demonstrates that the buoyancy weighing-bar method is suitable for measuring the particle size distribution of floating spherical solids. The precision of the resulting particle size distribution is comparable to that of the laser diffraction/scattering method as well as a direct measurement under the microscope.

浮力秤量法を用いて浮上性球形粒子の粒径分布を測定した．ソーダライムシリケートガラスビーズ(JIS試験用粉体2，GBL100)-ポリタングステン酸ナトリウム水溶液系と中空ガラス球(グラスバブルズ)-水系で検討を行った．実験で得られた粒径分布は，レーザー回折・散乱法や顕微鏡法で測定された粒径と同等であった．本研究によって，浮力秤量法が浮上性固体の粒径分布測定に適用できることがわかった．得られた粒径分布は，代表的な粒径測定法であるレーザー回折・散乱法，顕微鏡法と同等の精度である．


The Sensitivity of Drop motion due to the Density and Viscosity Ratio


A Computational Study of Dynamic Processes of a Bubble Rising in Carreau Model Fluids


Three-Dimensional Simulations of the Dynamic Motion of Single Drops Rising in Viscoelastic FENE-CR Model Fluids

The results of three-dimensional numerical simulations of the dynamic motion of single drops rising in viscoelastic Chilcott Rallison (FENE-CR) model fluids are presented. The simulations are performed using a combination of a coupled level-set/volume-of-fluid (CLSVOF) method and a hydrodynamic scheme with formal second-order accuracy. In our study, we address the rising motion of a drop exhibiting a range of small to large deformations. It is shown that the dynamic motion of the drop largely depends on the FENE-CR model parameters: the extensibility parameter L and the Deborah number strongly influence the viscoelastic characteristics of the drop. It is numerically shown that these parameters determine the characteristic cusp formation at the tail of the drop, similar to the case of bubble motion. We also discuss the difference between drop motion and bubble motion in viscoelastic FENE-CR model fluids.


Three-Dimensional Simulations of Vortex Ring Formation from Falling Drops in an Immiscible Viscous Liquid

We conduct a numerical study on the formation process of vortex rings that were observed in a previous experimental study. The numerical simulation of the process is challenging since it is a three-dimensional problem involving unstable drop motion. We use a method in which a three-dimensional domain is discretized; the coupled level-set/volume-of-fluid (CLSVOF) method is used to determine the motion of the drop interface and a sharp interface treatment is used for enforcing the boundary conditions at the drop interface. It is numerically shown that there are two different evolution regimes for vortex ring motion, depending on the value of the Eötvös number (Eo). The simulation results show that the transient evolution process of a vortex ring is sensitive to the drop size. Thus, our results agree with those of the previous experimental study. We also explore the effect of the viscosity ratio (=μD/μC) on vortex ring formation resulting from a falling drop.

Journal of Chemical Engineering of Japan


アルコールによる一酸化窒素の無触媒酸化反応

アルコールによる一酸化窒素の無触媒酸化反応


A Stable and Efficient Method for Treating Surface Tension in Incompressible Two-Phase Flow


New Measurement of Particle Size Distribution by Buoyancy Weighing-Bar Method


A Study of Freezing Phenomena in a Pipe with Small Amount of Water Flow Rate

微少流量円管流れの凍結現象に関する研究

In order to obtain knowledge for preventing water freeze in pipe in winter, we considered freezing phenomena in a pipe with small amount of water flow. The condition of flow rate Q established was 4.0×10-7 7.1×10-6 m3/s, and freezing phenomena for two different-sized pipes were investigated. As a result, freeze at the condition of Tw (the temperature of the inside wall)=-2 -3°C was generated. It was found that freeze was likely to occur as the contact time between water and cold wall became longer. On the one hand, in the condition of a very low temperature (Tw<-3°C), it was shown that we were not able to avoid freezing by a method in which a small amount of water flow is continuously flowed. For such severe condition, countermeasures such as water drain and heating pipe etc are necessary.

本研究では，冬季における水道管の凍結破損を防止するための知見を得るために円管内に微少流量(低速)の水を流した条件での凍結現象について検討した．流量条件は，Q=4.0×10-7–7.1×10-6 m3/sとし，大きさの異なる二つの円管で調べた．結果として，壁面温度TWがTW=-2–-3°C程度で凍結が生じ，冷却固体面と水との接触時間が長くなると凍結が起こりやすくなることがわかった．また，壁温が非常に低い温度条件下(TW<-3°C)では，微少流量の連続的流水では凍結を防止できず，このような厳しい温度条件では，水抜きや管を暖める等の対策が必要となることを示した．


The Transient Dynamics of a Small Bubble Rising in a Low Morton Number Regime


An Improved Sharp Interface Method for Viscoelastic and Viscous Two-Phase Flows


Direct Numerical Simulation of the Slow Formation Process of Single Bubbles in a Viscous Liquid

We present the computational results of the dynamics of single bubbles slowly formed from a submerged nozzle in a viscous liquid. Our simulations are carried out by a sharp interface coupled level set/volume-of-fluid (CLSVOF) method and the governing equations based on the CLSVOF method are solved through a hydrodynamic scheme with formal second-order accuracy. The application of two-phase computational fluid dynamics (CFD) for simulating bubble formation dynamics in a viscous liquid is a challenging task. We present unique, quantitative, comparisons between the results from CFD and experimental observations. As a result, it is shown that our computational method is robust to extreme variations in physical properties and extreme variations in interfacial topology, and it is shown that our method gives accurate results.

Journal of Chemical Engineering of Japan


高強度セメントの流動特性に関する基礎的研究

高強度セメントの流動特性に関する基礎的研究

セメント·コンクリート論文集


A Numerical Study of Coupled Natural and Thermocapillary Convection in a Cube

Advances and Applications in Fluid Mechanics


Improvements for Calculating Two-Phase Bubble and Drop Motion Using an Adaptive Sharp Interface Method


A Sharp Interface Method for Incompressible Two-Phase Flows


Three-Dimensional Computations of the Motion of a Newtonian Drop Rising through Immiscible Quiescent Shear-Thinning Liquids

Three-dimensional direct numerical simulations of the motion of a Newtonian drop rising in Carreau-Yasuda model fluids were carried out by a coupled level-set/volume-of-fluid (CLSVOF) method. Our numerical approach simulated faithfully the physical shear-thinning properties and 3D-nonlinear dynamics that are observed in experiments. Three-dimensional computational results showed that the local change in viscosity around a drop greatly depended on the drop shape and the shear-thinning properties of the quiescent liquid. We quantitatively considered the drop rise motion based on the modified dimensionless numbers (ReM and MM) and the effective viscosity.


Three-Dimensional Numerical Simulations of the Effect of Initial Bubble Conditions on the Motion of a Bubble Rising in Viscous Liquids

The effect of initial bubble conditions on the motion of a gas bubble rising in viscous liquids was investigated by 3D-computations. Then, a coupled level set/volume-of-fluid (CLSVOF) method was used as a numerical method. For high Eötvös and very low Morton numbers regions predicting a 3D ``spherical-cap'' bubble, it was computationally demonstrated that the resulting final state of bubbles depended on initial bubble conditions; bubbles with break-up at the center or ``spherical-cap'' bubbles depending on initial bubble conditions were reproduced. On the other hand, we showed for low Eo and high M conditions that initial bubble conditions did not affect the terminal state of bubble rising motion.

Journal of Chemical Engineering of Japan


A Computational Study of Bubble Motion in Newtonian and Viscoelastic Fluids


A Computational Study of the Effect of Initial Flow Conditions on the Motion of a Gas Bubble Rising in Viscous Liquids

International Journal of Multiphase Flow


Dynamic Processes in a Deformed Drop Rising through Shear-Thinning Fluids

Journal of Non-Newtonian Fluid Mechanics


Three-Dimensional Numerical Simulations of the Motion of a Gas Bubble Rising in Viscous Liquids

Three-dimensional direct numerical simulations of the motion of a gas bubble rising in viscous liquids were carried out by a coupled level-set/volume-of-fluid (CLSVOF) method which is comprised of a best mix of the advantages of both thevolume-of-fluid (VOF) and level-set (LS) methods. In our study, physical properties of real gas-liquid systems were introduced in the computations: the density ratio between both phases can be up to about 800 and the viscosity ratio reaches -50000. As a result, it will be presented that we can numerically predict three-dimensional bubble motion including nonlinear dynamics for the full range of bubble shapes and physical parameters (e.g. high Reynolds number) with good agreement with experiments. We shall describe the effectiveness and validity of our numerical (CLSVOF) method for two-phase flow.


A Numerical Study of the Motion of a Spherical Drop Rising in Shear-Thinning Fluid Systems


A Numerical Study on Natural Convective Heat Transfer of Pseudoplastic Fluids in a Square Cavity

Numerical Heat Transfer Part A Applications


Consideration of Evaluation Model of Mixture Physical Properties in Liquid-Liquid Fluid Systems

International Journal of Heat and Technology


Development of Ice Making Apparatus using Cold Winter Air

寒冷外気による氷片生成装置の開発

We propose a new method for producing ice by winter air in cold regions, and perform tests with an apparatus assembled as trial. The apparatus consists of two parts, a heat exchanger and an ice making part, to get high thermal efficiency. The tests yield the following results: 1) The production rate of ice is estimated to be 2---19 kg-h-' from the heat intake ability of the ice maker, which was obtained by the tests carried out at refrigerant (25 wt% calcium chloride) tempera-tures of -4.4- -14.5°C at the inlet of the ice maker and at refrigerant flow rates of 1. 0- 5.6 1-min-'. 2) The production rate of ice is 3.5-6.8 kg-h-' in the proof tests, which were carried out at outdoor temperatures of - 5 - -10°C (refrigerant temperatures of 3-8°C at the inlet of the ice maker) and refrigerant flow rates of 1.3-5.2 1-min-1.

寒冷地における寒冷外気による氷の生成において新しい方法を提案し，さらに試作装置による試験を行った．提案の方法は，液体冷媒を用い寒冷外気への放熱と氷の生成の過程を分離し高熱効率化を日指した．試作装置による試験の結果，氷片生成機の吸熱能力試験(液体冷媒氷生成機入りロ温度-4．4∼-4．5．C，液体冷媒流量1．0∼5．6t・min-1)においては，2∼19kg・h-1の氷の生成量が，実証試験(寒冷外気温度-5∼-10．C(液体冷媒氷生成機入りロ温度-3∼-80C)，液体冷媒流量1．3∼5．21・min-1)においては，3．5∼6．8kg．h-1の氷の生成量が得られた．


Numerical Study on Effect of Thermal Conditions at Side Walls on Natural Convective Heat Transfer in a Rectangular Duct


Characteristics of Heat Transfer from a Spherical Solid Body under Pulsating Forced Convection


ジメチルエーテルによるNOの無触媒酸化反応

ジメチルエーテルによるNOの無触媒酸化反応

Journal of the Japan Institute of Energy


Numerical Analysis of Mass Transfer in a Drop Formation Process under Pressure Pulse Conditions

Solvent Extraction Research and Development, Japan


Numerical Analysis of a Dispersed Drop Behavior in the Pulsed Sieve-Plate Extraction Column

International Communications in Heat and Mass Transfer


Numerical Analysis of Mass Transfer from a Free Motion Drop with Various Shapes in a Solvent Extraction Process


Numerical Analysis of Mass Transfer from a Free Motion Drop in a Solvent Extraction Process


Numerical Analysis of a Single Drop Formation Process under Pressure Pulse Condition


Separation Theory of Ternary Hydrogen Isotope by Thermal Diffusion Process Including Isotope Exchange Reaction

Journal of Chemical Engineering of Japan


Ternary Theory of Hydrogen Isotope Separation and Tritium Enrichment by the Thermal Diffusion Method with Isotope Exchange Reaction


水平矩形チャンネル内における気液二相流れの数値解析

水平矩形チャンネル内における気液二相流れの数値解析

化学工学シンポジウムシリーズ81

化学工学シンポジウムシリーズ81


擬塑性流体中での液滴運動状態の系統的整理

擬塑性流体中での液滴運動状態の系統的整理

化学工学シンポジウムシリーズ77

化学工学シンポジウムシリーズ77


CLSVOF法による気泡運動の数値解析

CLSVOF法による気泡運動の数値解析

化学工学シンポジウムシリーズ77

化学工学シンポジウムシリーズ77


垂直壁を流下する液膜のさざ波発生に関する数値的考察

垂直壁を流下する液膜のさざ波発生に関する数値的考察

化学工学シンポジウムシリーズ75

化学工学シンポジウムシリーズ75


キャビティ内のマランゴニ対流の数値解析~自由表面上での熱的境界条件の影響~

キャビティ内のマランゴニ対流の数値解析~自由表面上での熱的境界条件の影響~

化学工学シンポジウムシリーズ75

化学工学シンポジウムシリーズ75


境界適合座標を用いた数値解析による流下液膜のさざ波発生条件の検討

境界適合座標を用いた数値解析による流下液膜のさざ波発生条件の検討

化学工学シンポジウムシリーズ72

化学工学シンポジウムシリーズ72


低Re数で自由運動を行う球形液滴の内部循環流の数値解析

低Re数で自由運動を行う球形液滴の内部循環流の数値解析

化学工学シンポジウムシリーズ67

化学工学シンポジウムシリーズ67


分散相液滴の流動挙動の数値解析

分散相液滴の流動挙動の数値解析

化学工学シンポジウムシリーズ45

化学工学シンポジウムシリーズ45