Naoki Okamura, T. Fukui, M. Kawaguchi, K. Morinishi
{"title":"Influence of each cylinder’s contribution on the total effective viscosity of a two-dimensional suspension by a two-way coupling scheme","authors":"Naoki Okamura, T. Fukui, M. Kawaguchi, K. Morinishi","doi":"10.1299/jfst.2021jfst0020","DOIUrl":null,"url":null,"abstract":"Einstein’s viscosity formula is sometimes strongly limited for viscosity estimation of suspensions; that is, it is only applicable for low-concentration suspensions in which hydrodynamic interactions are sufficiently negligible. In particular, hydrodynamic interactions between particles (cylinders in two dimensions) should be taken into consideration when finite-size particles are suspended. Therefore, change in the microstructure, i.e., spatial arrangement of particles in the flow field, is important for understanding mechanism of suspension rheology. In order to provide better practical applications for viscosity estimation instead of Einstein’s formula, we investigated the influence of each cylinder’s contribution on the total effective viscosity of a suspension with finite-size cylinders considering the microstructure, especially in terms of cylinder-wall and cylinder-cylinder distances. Two-dimensional pressure-driven flow simulations were performed using the regularized lattice Boltzmann method and a two-way coupling scheme. The rigid circular cylinders suspended in a Newtonian fluid were assumed to be neutrally buoyant and non-Brownian. As a result, we found that both distances between cylinders and cylinder-wall are significant for viscosity estimation. In addition, the effective viscosity can be estimated accurately when the confinement is sufficiently low ( C ≈ 0.04). It can be stated that the microstructure of the suspension is one of the promising factors to estimate and control suspension rheology.","PeriodicalId":44704,"journal":{"name":"Journal of Fluid Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.7000,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"3","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Fluid Science and Technology","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1299/jfst.2021jfst0020","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"MECHANICS","Score":null,"Total":0}
引用次数: 3
Abstract
Einstein’s viscosity formula is sometimes strongly limited for viscosity estimation of suspensions; that is, it is only applicable for low-concentration suspensions in which hydrodynamic interactions are sufficiently negligible. In particular, hydrodynamic interactions between particles (cylinders in two dimensions) should be taken into consideration when finite-size particles are suspended. Therefore, change in the microstructure, i.e., spatial arrangement of particles in the flow field, is important for understanding mechanism of suspension rheology. In order to provide better practical applications for viscosity estimation instead of Einstein’s formula, we investigated the influence of each cylinder’s contribution on the total effective viscosity of a suspension with finite-size cylinders considering the microstructure, especially in terms of cylinder-wall and cylinder-cylinder distances. Two-dimensional pressure-driven flow simulations were performed using the regularized lattice Boltzmann method and a two-way coupling scheme. The rigid circular cylinders suspended in a Newtonian fluid were assumed to be neutrally buoyant and non-Brownian. As a result, we found that both distances between cylinders and cylinder-wall are significant for viscosity estimation. In addition, the effective viscosity can be estimated accurately when the confinement is sufficiently low ( C ≈ 0.04). It can be stated that the microstructure of the suspension is one of the promising factors to estimate and control suspension rheology.
期刊介绍:
Journal of Fluid Science and Technology (JFST) is an international journal published by the Fluids Engineering Division in the Japan Society of Mechanical Engineers (JSME). JSME had been publishing Bulletin of the JSME (1958-1986) and JSME International Journal (1987-2006) by the continuous volume numbers. Considering the recent circumstances of the academic journals in the field of mechanical engineering, JSME reorganized the journal editorial system. Namely, JSME discontinued former International Journals and projected new publications from the divisions belonging to JSME. The Fluids Engineering Division acted quickly among all divisions and launched the premiere issue of JFST in January 2006. JFST aims at contributing to the development of fluid engineering by publishing superior papers of the scientific and technological studies in this field. The editorial committee will make all efforts for promoting strictly fair and speedy review for submitted articles. All JFST papers will be available for free at the website of J-STAGE (http://www.i-product.biz/jsme/eng/), which is hosted by Japan Science and Technology Agency (JST). Thus papers can be accessed worldwide by lead scientists and engineers. In addition, authors can express their results variedly by high-quality color drawings and pictures. JFST invites the submission of original papers on wide variety of fields related to fluid mechanics and fluid engineering. The topics to be treated should be corresponding to the following keywords of the Fluids Engineering Division of the JSME. Basic keywords include: turbulent flow; multiphase flow; non-Newtonian fluids; functional fluids; quantum and molecular dynamics; wave; acoustics; vibration; free surface flows; cavitation; fluid machinery; computational fluid dynamics (CFD); experimental fluid dynamics (EFD); Bio-fluid.