担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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掲載種別：研究論文（学術雑誌）  

DOI： 10.1299/jbse.21-00205

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s12650-019-00613-1

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その他リンク： http://link.springer.com/article/10.1007/s12650-019-00613-1/fulltext.html

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3154/tvsj.40.23

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本混相流学会  

Dynamic wetting of a solid sphere has been simulated numerically. We have developed the model for the description of the moving contact lines on curved solid surfaces by combining the GNBC-Front-tracking method and the immersed boundary method. The model was applied to the simulation of a quasi-static penetration of a water-repellent sphere into the water. As a result, the shape of the interface for different wettability is in good agreement with the previous experimental results. The residual bubble volume was evaluated under the different sphere size, static contact angle, and penetrating velocity conditions. The present results show a similar trend to the experimental and theoretical ones that the water-repellent sphere has a larger bubble since it incorporates more volume of air into the water, indicating the dynamic wetting of the sphere surface can be reproduced by the model.

DOI： 10.3811/jjmf.29.443

CiNii Books

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その他リンク： https://jlc.jst.go.jp/DN/JLC/20022372701?from=CiNii

記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CAMBRIDGE UNIV PRESS  

The lateral migration properties of a rigid spherical particle suspended in a pressure-driven flow through channels with square cross-sections were investigated numerically, in the range of Reynolds numbers (Re) from 20 to 1000. 'The flow field around the particle was computed by the immersed boundary method to calculate the lateral forces exerted on the particle and its trajectories, starting from various initial positions. 'The numerical simulation showed that eight equilibrium positions of the particle are present at the centres of the channel faces and near the corners of the chatmel cross-section. 'Me equilibrium positions at the centres of the channel faces are always stable, whereas the equilibrium positions at the corners are unstable until Re exceeds a certain critical value, Re-e. At Re Re-e additional equilibrium positions appear on a heteroclinic orbit that joins the channel face and corner equilibrium positions, and the lateral forces along the heteroclinic orbit are very small. As Re increases, the channel face equilibrium positions are shifted towards the channel wall at first, and then shifted away from the channel wall. The channel corner equilibrium positions exhibit a monotonic shift towards the channel corner with increasing Re. Migration behaviours of the particle in the cross-section are also predicted for various Values of Re. rftlese numerical results account for the experimental observations of particle distributions in the cross-section of micro and millimetre scale channels, including the characteristic alignment and focusing of the particles, the absence of the corner equilibrium positions at low Re and the progressive shift of the equilibrium positions with Re.

DOI： 10.1017/jfm.2015.456

Web of Science

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japanese Society of Biorheology  

The vascular endothelial surface glycocalyx layer consists of fibrous glycoproteins with a thickness of several hundred nanometers to a few microns. The present study focuses on the function of the glycocalyx layer as a modulator of permeability in water transport across the blood vessel wall. A particulate layer model is developed to analyze the fluid permeation through the glycocalyx layer, which has periodic fibrous structures and finite thickness. Theoretical and numerical computations of the permeation resistance across the layer are performed based on the Stokesian dynamics approach. The results show that the resistance near the ends of the layer is affected considerably by the anisotropy of adjacent particle configurations. We describe such an end effect on the permeability in relation to the layer thickness and particle spacing ratio. It is suggested that the variations in thickness or fiber spacing in the glycocalyx layer could significantly alter its fluid permeation properties.

DOI： 10.17106/jbr.29.11

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

Mass transfer in porous media has been investigated experimentally. In this paper, we present a visualization technique and discuss the behavior of a substance which transfers under the influence of gravity and reacts with the surface of porous media. Mass transfer by the reaction with porous media was demonstrated by means of electrochemical deposition experiment on particulate beds with complex structures. A copper plate (anode) and a stainless steel particulate bed (cathode) were, respectively, placed at the upper and bottom side of a thin vertical cell which was filled with copper sulfate solution. After the application of electricity, cupric ion which is provided from the copper plate to the solution transfers under the influence of gravity and it is consumed by deposition at the particulate bed. The behavior of ions between the electrodes was visualized by utilizing the infrared absorption characteristics of cupric ion. We observed gravitational instability and convection flow due to concentration gradient of ions in opposite direction to that of gravity, which is formed by reaction at solid-liquid interfaces. While downward flow caused by Rayleigh-Taylor instability was observed in the case of flat interfaces, upward flow generated from complex-shaped interfaces was greatly dependent on their geometry. The interaction of these flows resulted in the convection throughout the cell. Consequently, it is found from the results that the gravitational instability significantly varies the transport characteristics and that the reactive interface geometry greatly affects the overall mass transfer.

DOI： 10.1007/s12650-013-0183-0

Web of Science

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記述言語：日本語  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Fluid permeability of polydisperse particulate bed with finite thickness has been examined. On the assumption of creeping flow, the permeability of monodisperse particles with arbitrary arrangement is calculated by means of Stokesian dynamics approach in which the interaction between individual particles and interstitial fluid is described by multipole expansion of the Oseen tensor. We have extended such calculation method to polydisperse particulate systems which have not so dense structures (up to particle volume fraction φ ~ 0.2). The particles are located infinitely in space and their interaction has been taken into account by Ewald summation technique. For the spatial distribution of polydisperse particles, we consider locally stratified particulate beds and define stratification degree as a parameter which apparently and mathematically represents the thickness of the mixing region of different-sized particles. The permeability profiles in the particulate beds with different stratification degree show the dependence of local permeability on the spatial and size distribution of particles. Consequently, the calculation results indicate that the permeability of non-uniform polydisperse particulate bed can be predicted by integrating the local permeation resistance which is determined by the local specific surface area. © 2012 Springer Science+Business Media Dordrecht.

DOI： 10.1007/s11242-012-0098-6

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：TAYLOR & FRANCIS INC  

Permeability through media having various structures has been studied theoretically. We consider loose porous media, like fibrous materials, and media with a localized pore network, like fractured rocks. We model complicated porous structures by using assemblage of spherical particles. The calculations of permeability are performed by the Stokesian dynamic approach, which enables us to derive fluid motion in the presence of many particles. The Ewald summation technique is employed to represent infinite and finite particulate beds. In the infinite bed where the particles exist endlessly in space, we investigate how the internal structure of the media affects permeability. The results indicate that permeability significantly depends on internal structure, particularly the void geometry. In the finite bed where the particles form a bed with finite thickness, we discuss permeability variance due to the presence of ends. It is found that permeability greatly varies in the vicinity of ends owing to the anisotropy of the flow field, which arises from the presence of ends.

DOI： 10.1080/02726351.2010.488715

Web of Science

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

The hydrodynamic effect on a thin particle layer, which moves relative to fluid by an external force, is investigated theoretically and numerically. Because of the presence of layer ends, the arrangement of particles in the layer is anisotropic and the drag force acting on them varies according to the position. The resulting relative motion of particles brings about the spreading of the layer. We have studied such a diffusive behavior of particle layers, which have various internal arrangements. We have assumed a non-Brownian system in which the particles move relatively owing to only the variance of hydrodynamic force. The hydrodynamic force on each particle was calculated by Stokesian dynamics approach. The results show that the relative motion of particles is greatly influenced by the internal arrangement of the particle layer. In consequence, the overall diffusive motion of particle layer varies with the arrangement even if the particle concentration is similar. It is in contrast to the gradient diffusion of Brownian particles.

DOI： 10.1103/PhysRevE.80.066311

Web of Science

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