Volume 3: Fluid Mechanics; Micro and Nano Fluid Dynamics; Multiphase Flow最新文献

Liutex Core Line for Vortex Structure in Turbulence 湍流中涡结构的流芯线

Volume 3: Fluid Mechanics; Micro and Nano Fluid Dynamics; Multiphase Flow Pub Date : 2021-08-10 DOI: 10.1115/fedsm2021-66012

Oscar Alvarez, Yifei Yu, Chaoqun Liu

{"title":"Liutex Core Line for Vortex Structure in Turbulence","authors":"Oscar Alvarez, Yifei Yu, Chaoqun Liu","doi":"10.1115/fedsm2021-66012","DOIUrl":"https://doi.org/10.1115/fedsm2021-66012","url":null,"abstract":"\u0000 Liutex is a vortex identification method that provides a vector interpretation of local fluid rotation. Liutex produces a vector quantity which can be used to determine the absolute and relative strength of a vortex, the local rotation axis of a vortex, the vortex core center, the size of the vortex core, and the vortex boundary. Vortex identification and visualization is essential in computational fluid turbulence analysis and fluid mechanics in general. Until Liutex, there has not been a way to identify the core of a vortex structure or even the center of rotation of a vortex structure. Since Liutex, tools have been created to assist in the identification and analysis of vortical structures. The Liutex Core Line has been developed to better understand turbulent fluid structures. A Liutex core is defined as a concentration of Liutex vectors and defined to be unique and the Liutex core line is the center of rotation of that Liutex core. Currently, iso-surfaces are the most popular way to visualize the structure of turbulent flow but there is no reason to believe that it is the best way to represent a vortex’s structure. Previous methods that use iso-surface are strongly threshold dependent and since the Liutex core line is unique, it is independent of threshold and can show the real vortex structure. In this paper we show the benefits and promises of the Liutex Core Line as a better way of representing vortex structures.","PeriodicalId":245509,"journal":{"name":"Volume 3: Fluid Mechanics; Micro and Nano Fluid Dynamics; Multiphase Flow","volume":"515 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116167467","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}

引用次数: 0

Shock-Induced Multiphase Instability in a High Volume Fraction Finite-Thickness Particle Layer 高体积分数有限厚度颗粒层中激波诱导的多相不稳定性

Volume 3: Fluid Mechanics; Micro and Nano Fluid Dynamics; Multiphase Flow Pub Date : 2021-08-10 DOI: 10.1115/fedsm2021-65446

B. Rollin, F. Ouellet, B. Durant, R. Koneru, S. Balachandar

{"title":"Shock-Induced Multiphase Instability in a High Volume Fraction Finite-Thickness Particle Layer","authors":"B. Rollin, F. Ouellet, B. Durant, R. Koneru, S. Balachandar","doi":"10.1115/fedsm2021-65446","DOIUrl":"https://doi.org/10.1115/fedsm2021-65446","url":null,"abstract":"\u0000 We study the interaction of a planar air shock with a perturbed, monodispersed, particle curtain using point-particle simulations. In this Eulerian-Lagrangian approach, equations of motion are solved to track the position, momentum, and energy of the computational particles while the carrier fluid flow is computed in the Eulerian frame of reference. In contrast with many Shock-Driven Multiphase Instability (SDMI) studies, we investigate a configuration with an initially high particle volume fraction, which produces a strongly two-way coupled flow in the early moments following the shock-solid phase interaction. In the present study, the curtain is about 4 mm in thickness and has a peak volume fraction of about 26%. It is composed of spherical particles of d = 115μm in diameter and a density of 2500 kg.m−3, thus replicating glass particles commonly used in multiphase shock tube experiments or multiphase explosive experiments. We characterize both the evolution of the perturbed particle curtain and the gas initially trapped inside the particle curtain in our planar three-dimensional numerical shock tube. Control parameters such as the shock strength, the particle curtain perturbation wavelength and particle volume fraction peak-to-trough amplitude are varied to quantify their influence on the evolution of the particle cloud and the initially trapped gas. We also analyze the vortical motion in the flow field. Our results indicate that the shock strength is the primary contributor to the cloud particle width. Also, a classic Richtmyer-Meshkov instability mixes the gas initially trapped in the particle curtain and the surrounding gas. Finally, we observe that the particle cloud contribute to the formation of longitudinal vortices in the downstream flow.","PeriodicalId":245509,"journal":{"name":"Volume 3: Fluid Mechanics; Micro and Nano Fluid Dynamics; Multiphase Flow","volume":"71 5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116385610","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}

引用次数: 0

A CNN With Deep Learning for Non-Equilibrium Characterization of Al-Sm Melt Infusion Into a B4C Packed Bed 基于CNN深度学习的Al-Sm熔体注入B4C填充床非平衡态表征

Volume 3: Fluid Mechanics; Micro and Nano Fluid Dynamics; Multiphase Flow Pub Date : 2021-08-10 DOI: 10.1115/fedsm2021-65794

J. Aguilar, Laura Sandoval, Arturo Rodríguez, Sanjay Kumar, Jose Terrazas, Richard Adansi, Vinod Kumar, A. Bronson

{"title":"A CNN With Deep Learning for Non-Equilibrium Characterization of Al-Sm Melt Infusion Into a B4C Packed Bed","authors":"J. Aguilar, Laura Sandoval, Arturo Rodríguez, Sanjay Kumar, Jose Terrazas, Richard Adansi, Vinod Kumar, A. Bronson","doi":"10.1115/fedsm2021-65794","DOIUrl":"https://doi.org/10.1115/fedsm2021-65794","url":null,"abstract":"\u0000 In seeking predictability of characterizing materials for ultra-high temperature materials for hypersonic vehicles, the use of the convolutional neural network for characterizing the behavior of liquid Al-Sm-X (Hf, Zr, Ti) alloys within a B4C packed to determine the reaction products for which they are usually done with the scanning electron microscope (SEM) or X-ray diffraction (XRD) at ultra-high temperatures (> 1600°C). Our goal is to predict ultimately the products as liquid Al-Sm-X (Hf, Zr, Ti) alloys infiltrate into a B4C packed bed. Material characterization determines the processing path and final species from the reacting infusion consisting of fluid flow through porous channels, consumption of elemental components, and reaction forming boride and carbide precipitates. Since characterization is time-consuming, an expert in this field is required; our approach is to characterize and track these species using a Convolutional Neural Network (CNN) to facilitate and automate analysis of images. Although Deep Learning seems to provide an automated prediction approach, some of these challenges faced under this research are difficult to overcome. These challenges include data required, accuracy, training time, and computational cost requirements for a CNN. Our approach was to perform experiments on high-temperature metal infusion under B4C Packed Bed infiltration in a parametric matrix of cases. We characterized images using SEM and XRD images and run/optimize our CNN, which yields an innovative method for characterization via Deep Learning compared to traditional practices.","PeriodicalId":245509,"journal":{"name":"Volume 3: Fluid Mechanics; Micro and Nano Fluid Dynamics; Multiphase Flow","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114413691","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}

引用次数: 0

Behavior of Cell Passing Through Micro Slit Between Micro Machined Plates 细胞通过微加工板间微缝的行为

Volume 3: Fluid Mechanics; Micro and Nano Fluid Dynamics; Multiphase Flow Pub Date : 2021-08-10 DOI: 10.1115/fedsm2021-65209

S. Hashimoto, K. Yoshinaka, Hiroki Yonezawa

引用次数: 0

Elementary Numerical Analysis of Wet Foam Formation and Study of Its Flow Structures and Physical Behavior 湿泡沫形成的初步数值分析及其流动结构和物理行为研究

Volume 3: Fluid Mechanics; Micro and Nano Fluid Dynamics; Multiphase Flow Pub Date : 2021-08-10 DOI: 10.1115/fedsm2021-65627

E. Shirani, S. Nasirzade, F. Aloui

{"title":"Elementary Numerical Analysis of Wet Foam Formation and Study of Its Flow Structures and Physical Behavior","authors":"E. Shirani, S. Nasirzade, F. Aloui","doi":"10.1115/fedsm2021-65627","DOIUrl":"https://doi.org/10.1115/fedsm2021-65627","url":null,"abstract":"\u0000 The purpose of this study is to analyze the flow of wet foam and to study the effect of volume fraction, velocity and surface tension and other physical parameters on the foam flow. The most numerical researches done in this area are for single-phase flows. The numerical simulation in this study is the first simulation in the foam flow, in which both the bubbles and the water are simulated as two-phase flow. In this study, fluid containing a surfactant and bubbles are flowing in a duct. The dimensions of the duct cross section is 15 × 60 in millimeters. The numerical solution is performed for three Reynolds numbers of 50, 100 and 1000, three volume fractions of 48, 41 and 28, and three Weber numbers of 0.405, 0.27 and 0.203 (27 different modes), and the effect of the above parameters on the flow behavior and its physical properties have been investigated.\u0000 It was found that in foam flow, the velocity fluctuations, due to the movement of bubbles in the flow, is in the order of magnitude of the mean velocity. The same is true for wall shear stress. By increasing the Reynolds number, the pressure loss increases, the magnitude of the velocity fluctuations decreases and the frequency of the velocity fluctuations increases. By increasing the Weber number, the pressure loss and the magnitude of the velocity fluctuations decrease and the mean shear stress increases. By increasing the foam quality, pressure loss increases, the mean shear stress and the magnitude of the velocity fluctuations decrease and its frequency increases. And the phenomenon of coalescence causes a sudden increase in momentum speed.","PeriodicalId":245509,"journal":{"name":"Volume 3: Fluid Mechanics; Micro and Nano Fluid Dynamics; Multiphase Flow","volume":"80 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126361300","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}

引用次数: 0

Performance of Kaplan Turbine Operating at Design Condition 卡普兰汽轮机在设计工况下的运行性能

Volume 3: Fluid Mechanics; Micro and Nano Fluid Dynamics; Multiphase Flow Pub Date : 2021-08-10 DOI: 10.1115/fedsm2021-65561

Muhannad Altimemy, Saif Watheq, Justin Caspar, A. Oztekin

{"title":"Performance of Kaplan Turbine Operating at Design Condition","authors":"Muhannad Altimemy, Saif Watheq, Justin Caspar, A. Oztekin","doi":"10.1115/fedsm2021-65561","DOIUrl":"https://doi.org/10.1115/fedsm2021-65561","url":null,"abstract":"\u0000 Design and optimization using computational fluid dynamics to enhance the hydro turbine’s performance are becoming gradually more common because of its flexibility, minor detailed flow description, and cost-effectiveness. These features are not easily achievable in model testing. k–ω simulations conducted in OpenFOAM 7 characterize the flow structure inside an industrial-sized Kaplan turbine module operating at the peak design flowrate. The power signal, velocity, vorticity, and pressure field are presented over the blades and throughout the draft tube. Additionally, pressure fluctuations were probed along the draft tube wall. The simulation shows a tip vortex rope in the narrow gap between the blade tip and turbine casing. The strong influence of the swirl leaving the runner had a negative impact on the flow pressure fluctuation. Also, high vortical activity was presented near the draft tube wall, leading to turbine instability. It was demonstrated that the turbine generates 14.923 MW of average power. The power signal showed minor fluctuations induced by the vortical activity close to the runner region and the corresponding pressure fluctuations. The Fast Fourier Transform showed the system is dominated by low frequency, high amplitude fluctuations.","PeriodicalId":245509,"journal":{"name":"Volume 3: Fluid Mechanics; Micro and Nano Fluid Dynamics; Multiphase Flow","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125449428","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}

引用次数: 1

Can Bump Arrays Separate Particles From Turbulent Flows? 碰撞阵列能将粒子与湍流分离吗?

Volume 3: Fluid Mechanics; Micro and Nano Fluid Dynamics; Multiphase Flow Pub Date : 2021-08-10 DOI: 10.1115/fedsm2021-67696

L. Pease, Jason E. Serkowski, T. Veldman, J. Willams, Xiao‐Ying Yu, M. Minette, J. Bamberger, C. Burns

引用次数: 0

Flow Characterization of an Industrial Size Francis Turbine Operating at Ultra-Low Load – The Effect of Water Injection 工业级混流式水轮机超低负荷运行的流动特性——注水效应

Volume 3: Fluid Mechanics; Micro and Nano Fluid Dynamics; Multiphase Flow Pub Date : 2021-08-10 DOI: 10.1115/fedsm2021-65559

Muhannad Altimemy, Justin Caspar, Saif Watheq, A. Oztekin

{"title":"Flow Characterization of an Industrial Size Francis Turbine Operating at Ultra-Low Load – The Effect of Water Injection","authors":"Muhannad Altimemy, Justin Caspar, Saif Watheq, A. Oztekin","doi":"10.1115/fedsm2021-65559","DOIUrl":"https://doi.org/10.1115/fedsm2021-65559","url":null,"abstract":"\u0000 Large Eddy Simulations (LES) are carried out for a Francis turbine operating at an ultra-low load with and without injection. The flow rate of the turbine is 40% of the design value. The injection aims to improve turbine operation for the already unstable base case away from the design flow rate. Tangential water injection was introduced through the draft tube wall in the same and opposite runner rotation direction. The injection angle was varied (15°, 30°, 45° and 60°). Two water injection rates were applied at 4% and 8 % of the optimal design flowrate. While injection with the 4% rate and 30° in the opposite runner rotation direction helped reduce pressure fluctuations downstream of the injection inlets; no injection configuration could completely mitigate the power and pressure fluctuations. The injection was found to increase the amplitude of pressure fluctuations close to the injection inlets by 2 to 20 times the magnitude of fluctuations without injection. There was a slight reduction in mean power production (4–10% loss) by injection. The high amplitude fluctuations were observed in power signals with and without the injection.","PeriodicalId":245509,"journal":{"name":"Volume 3: Fluid Mechanics; Micro and Nano Fluid Dynamics; Multiphase Flow","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129866068","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}

引用次数: 0

Behavior of Cell Under Wall Shear Stress in Flow Field: Comparison Among Cell Types 流场壁面剪切应力作用下细胞的行为:不同类型细胞的比较

Volume 3: Fluid Mechanics; Micro and Nano Fluid Dynamics; Multiphase Flow Pub Date : 2021-08-10 DOI: 10.1115/fedsm2021-65205

S. Hashimoto, K. Yoshinaka, Hiroki Yonezawa

{"title":"Behavior of Cell Under Wall Shear Stress in Flow Field: Comparison Among Cell Types","authors":"S. Hashimoto, K. Yoshinaka, Hiroki Yonezawa","doi":"10.1115/fedsm2021-65205","DOIUrl":"https://doi.org/10.1115/fedsm2021-65205","url":null,"abstract":"\u0000 Does the hysteresis effect remain in each cell after division? In the present study, the cell activity has been investigated after division under a shear stress field. To apply the constant shear stress field on cells, a Couette type flow device has been manufactured: between parallel walls (a lower stationary culture disk, and an upper rotating disk) with a constant gap. The wall shear stress was controlled by the rotating speed of the upper disk. Four types of cells were used in the test: C2C12 (mouse myoblast cell line), HUVEC (Human Umbilical Vein Endothelial Cells), 3T3-L1 (mouse fat precursor cells), and L929 (mouse fibroblast connective tissue). After cultivation without flow for 24 hours for adhesion of cells on the lower plate, the shear stress of 1 Pa was continuously applied on cells for 7 days at 310 K. The behavior (alignment and deformation) of each cell was traced at the time lapse image observed by an inverted phase contrast microscope placed in an incubator. The experimental results show the following behavior of each type of cell: C2C12 tends to return to the same direction as that of before division. Deformed 3T3-L1 tends to tilt to the flow direction.","PeriodicalId":245509,"journal":{"name":"Volume 3: Fluid Mechanics; Micro and Nano Fluid Dynamics; Multiphase Flow","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127176435","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}

引用次数: 0

Influence of Wall Proximity on the Wake Dynamics Behind a Square Cylinder 壁面接近度对方形圆柱后尾迹动力学的影响

Volume 3: Fluid Mechanics; Micro and Nano Fluid Dynamics; Multiphase Flow Pub Date : 2021-08-10 DOI: 10.1115/fedsm2021-65593

Samuel Addai, A. Mante, S. Kumahor, Xingjun Fang, M. Tachie

{"title":"Influence of Wall Proximity on the Wake Dynamics Behind a Square Cylinder","authors":"Samuel Addai, A. Mante, S. Kumahor, Xingjun Fang, M. Tachie","doi":"10.1115/fedsm2021-65593","DOIUrl":"https://doi.org/10.1115/fedsm2021-65593","url":null,"abstract":"\u0000 In the present study, the effects of wall proximity on the wake dynamics behind a square cylinder subjected to a thick upstream turbulent boundary layer were experimentally investigated using particle image velocimetry. The Reynolds number based on the free-stream velocity and the cylinder height (h) was 12750 while the ratio of the turbulent boundary layer thickness to the cylinder height was 3.6. The gap distance (G) between the bottom face of the cylinder and the wall was varied, resulting in gap ratios (G/h) of 0, 0.3, 0.5, 1.0, 2.0 and 8.0. The flow topological differences among the various gap ratios were analyzed in terms of the mean flow and Reynolds stresses. The results show that as the cylinder approaches the wall, the mean flow becomes increasingly asymmetric about the horizontal centerline of the cylinder and the size of the mean separation bubbles in the cylinder wake increases. Also, the magnitudes of the Reynolds stresses decrease with decreasing gap ratio. For G/h > 0, the distributions of the streamwise Reynolds normal stress and Reynolds shear stress are concentrated along the upper and lower separated shear layers, resulting in characteristic double peaks. The distributions of the vertical Reynolds normal stress, however, are concentrated in the wake about the horizontal centerline of the cylinder and reveal only single peaks.","PeriodicalId":245509,"journal":{"name":"Volume 3: Fluid Mechanics; Micro and Nano Fluid Dynamics; Multiphase Flow","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129011074","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}

引用次数: 0