Pub Date : 2023-01-01DOI: 10.1299/jfst.2023jfst0019
Y. Shigenaga, H. Hasegawa
{"title":"Wake flow visualization of a dandelion pappus with posture change","authors":"Y. Shigenaga, H. Hasegawa","doi":"10.1299/jfst.2023jfst0019","DOIUrl":"https://doi.org/10.1299/jfst.2023jfst0019","url":null,"abstract":"","PeriodicalId":44704,"journal":{"name":"Journal of Fluid Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66308074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1299/jfst.2023jfst0012
Yu-Hsin Chen, J. Miau, Yen-Po Chen, yng-ru chen
{"title":"Blunt leading-edge effect on spanwise-varying leading-edge contours of an UCAV configuration","authors":"Yu-Hsin Chen, J. Miau, Yen-Po Chen, yng-ru chen","doi":"10.1299/jfst.2023jfst0012","DOIUrl":"https://doi.org/10.1299/jfst.2023jfst0012","url":null,"abstract":"","PeriodicalId":44704,"journal":{"name":"Journal of Fluid Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66308348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1299/jfst.2023jfst0030
Zhuang Li, Changlun Sun, C. Pham, S. Yeom, H. Shin
{"title":"A preliminary attempt to combine in situ CT measurements with permeability tests of fractured granite cores","authors":"Zhuang Li, Changlun Sun, C. Pham, S. Yeom, H. Shin","doi":"10.1299/jfst.2023jfst0030","DOIUrl":"https://doi.org/10.1299/jfst.2023jfst0030","url":null,"abstract":"","PeriodicalId":44704,"journal":{"name":"Journal of Fluid Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66308603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1299/jfst.2023jfst0033
Yusuke Yugeta, Kosetsu Uji, Toshitaka Itoh, Y. Hasegawa
{"title":"Prediction of optimal control input in a fully developed turbulent channel flow by machine learning","authors":"Yusuke Yugeta, Kosetsu Uji, Toshitaka Itoh, Y. Hasegawa","doi":"10.1299/jfst.2023jfst0033","DOIUrl":"https://doi.org/10.1299/jfst.2023jfst0033","url":null,"abstract":"","PeriodicalId":44704,"journal":{"name":"Journal of Fluid Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66308612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1299/jfst.2023jfst0034
Nobuyuki OSHIMA
This study proposes a novel approach for the wall-boundary immersed flow simulation, wherein the Navier-Stokes equation is modified to include a level-set definition of a solid body in fluid flow. The proposed numerical model is defined via a system of differential equations based on the law of conservation and has a continuous approximate profile near the solid body. It yields a stable viscosity solution using a simple algorithm and scheme without any upwind schemes, numerical limiters, or addition filters. The model is numerically validated via solutions of flow around a cylinder, which are consistent with theoretical and experimental results for both steady and unsteady cases based on the wide Reynolds number (Re=8–160) of laminar flow condition.
{"title":"A novel approach for wall-boundary immersed flow simulation (proposal of modified Navier-Stokes equation)","authors":"Nobuyuki OSHIMA","doi":"10.1299/jfst.2023jfst0034","DOIUrl":"https://doi.org/10.1299/jfst.2023jfst0034","url":null,"abstract":"This study proposes a novel approach for the wall-boundary immersed flow simulation, wherein the Navier-Stokes equation is modified to include a level-set definition of a solid body in fluid flow. The proposed numerical model is defined via a system of differential equations based on the law of conservation and has a continuous approximate profile near the solid body. It yields a stable viscosity solution using a simple algorithm and scheme without any upwind schemes, numerical limiters, or addition filters. The model is numerically validated via solutions of flow around a cylinder, which are consistent with theoretical and experimental results for both steady and unsteady cases based on the wide Reynolds number (Re=8–160) of laminar flow condition.","PeriodicalId":44704,"journal":{"name":"Journal of Fluid Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135505123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1299/jfst.2023jfst0002
K. Fukagata
{"title":"Reduced order modeling of fluid flows using convolutional neural networks","authors":"K. Fukagata","doi":"10.1299/jfst.2023jfst0002","DOIUrl":"https://doi.org/10.1299/jfst.2023jfst0002","url":null,"abstract":"","PeriodicalId":44704,"journal":{"name":"Journal of Fluid Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66307339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1299/jfst.2023jfst0016
J. Aono, K. Kitamura
Multiphase flows arise in various fields that involve complicated phenomena. Studies have shown that COVID-19 can occur via air microdroplets, and breathing jets with microdroplets turn into turbulent cloud or puffs in cases of coughing and sneezing (Bourouiba et al., 2014). Microdroplets are upturned by buoyancy in the turbulent cloud and transported without falling. Furthermore, they float in air for hours and can be transported over long distances (Mittal et al., 2020). This scenario also involves a mixed phase flow of air and droplets. To simulate these phenomena, a numerical model assuming mechanical and thermal non-equilibrium multiphase flow is required to predict the range of turbulent cloud transport. In this study, to better simulate the turbulent cloud trajectories, a viscosity term is added to a two-phase flow six-equation model (two-fluid modeling or effective-fluid modeling, EFM) developed by Liou et al. (2008). It is a development of a parameter-free, viscous multiphase flow code, based on a single-phase compressible finite-volume solver (Kitamura et al., 2013). This solver is validated in the Poiseuille flow and laminar-flat-plate problem with an isothermal wall through a comparison with the analytical solutions. A detailed simulation of coughing is performed. The location of the turbulent cloud upturned by buoyancy is compared with the data of past studies.
多相流在涉及复杂现象的各个领域都有出现。研究表明，COVID-19可通过空气微滴传播，在咳嗽和打喷嚏的情况下，带有微滴的呼吸射流会变成湍流云或泡状物(Bourouiba et al.， 2014)。微液滴在湍流云中的浮力作用下向上翻转，并在不下落的情况下运输。此外，它们在空气中漂浮数小时，可以长距离运输(Mittal et al.， 2020)。这种情况还涉及空气和液滴的混合相流。为了模拟这些现象，需要一个假设力学和热非平衡多相流的数值模型来预测湍流云输送的范围。在本研究中，为了更好地模拟湍流云轨迹，在Liou等人(2008)开发的两相流六方程模型(双流体建模或有效流体建模，EFM)中加入了粘度项。它是基于单相可压缩有限体积求解器(Kitamura et al.， 2013)开发的无参数粘性多相流代码。通过与解析解的比较，验证了该求解方法在泊泽维尔流和等温壁层流平板问题中的有效性。对咳嗽进行了详细的模拟。并与以往的研究资料进行了比较。
{"title":"Development of parameter-free, two-fluid, viscous multiphase flow solver for cough-droplet simulations","authors":"J. Aono, K. Kitamura","doi":"10.1299/jfst.2023jfst0016","DOIUrl":"https://doi.org/10.1299/jfst.2023jfst0016","url":null,"abstract":"Multiphase flows arise in various fields that involve complicated phenomena. Studies have shown that COVID-19 can occur via air microdroplets, and breathing jets with microdroplets turn into turbulent cloud or puffs in cases of coughing and sneezing (Bourouiba et al., 2014). Microdroplets are upturned by buoyancy in the turbulent cloud and transported without falling. Furthermore, they float in air for hours and can be transported over long distances (Mittal et al., 2020). This scenario also involves a mixed phase flow of air and droplets. To simulate these phenomena, a numerical model assuming mechanical and thermal non-equilibrium multiphase flow is required to predict the range of turbulent cloud transport. In this study, to better simulate the turbulent cloud trajectories, a viscosity term is added to a two-phase flow six-equation model (two-fluid modeling or effective-fluid modeling, EFM) developed by Liou et al. (2008). It is a development of a parameter-free, viscous multiphase flow code, based on a single-phase compressible finite-volume solver (Kitamura et al., 2013). This solver is validated in the Poiseuille flow and laminar-flat-plate problem with an isothermal wall through a comparison with the analytical solutions. A detailed simulation of coughing is performed. The location of the turbulent cloud upturned by buoyancy is compared with the data of past studies.","PeriodicalId":44704,"journal":{"name":"Journal of Fluid Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66308235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1299/jfst.2023jfst0029
Daisuke Tsuneoka, J. Okajima
{"title":"Numerical simulation of two-phase flow in a microchannel for evaluating liquid film thickness and its Reynolds number dependency","authors":"Daisuke Tsuneoka, J. Okajima","doi":"10.1299/jfst.2023jfst0029","DOIUrl":"https://doi.org/10.1299/jfst.2023jfst0029","url":null,"abstract":"","PeriodicalId":44704,"journal":{"name":"Journal of Fluid Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66308601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1299/jfst.2023jfst0010
T. Ando, T. Shakouchi, Atsushi Hanai, Nobuyuki Hayashi, Yohei Fukuta, K. Tsujimoto, Mamoru Takahashi
{"title":"Effects of contraction ratio on loss reduction of the flow in the reducing elbow duct with a weir-shaped obstacle","authors":"T. Ando, T. Shakouchi, Atsushi Hanai, Nobuyuki Hayashi, Yohei Fukuta, K. Tsujimoto, Mamoru Takahashi","doi":"10.1299/jfst.2023jfst0010","DOIUrl":"https://doi.org/10.1299/jfst.2023jfst0010","url":null,"abstract":"","PeriodicalId":44704,"journal":{"name":"Journal of Fluid Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66307641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1299/jfst.2023jfst0007
S. Yamada, T. Tsujita
{"title":"Fluidic force and wake velocity of 3D body with four limbs in uniform flow","authors":"S. Yamada, T. Tsujita","doi":"10.1299/jfst.2023jfst0007","DOIUrl":"https://doi.org/10.1299/jfst.2023jfst0007","url":null,"abstract":"","PeriodicalId":44704,"journal":{"name":"Journal of Fluid Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66307866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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