Physics of Fluids最新文献_第7页

Using entropy balance to determine multiphase flow distribution in thermally decoupled parallel channels with shared inlet and outlet headers 利用熵平衡确定带有共用入口和出口集流管的热解耦平行通道中的多相流分布

Physics of Fluids Pub Date : 2024-05-01 DOI: 10.1063/5.0207373

Toochukwu Aka, Shankar Narayan

{"title":"Using entropy balance to determine multiphase flow distribution in thermally decoupled parallel channels with shared inlet and outlet headers","authors":"Toochukwu Aka, Shankar Narayan","doi":"10.1063/5.0207373","DOIUrl":"https://doi.org/10.1063/5.0207373","url":null,"abstract":"Multiphase flow with boiling in parallel channels is often an efficient approach to managing heat and energy distribution in several engineering systems. However, two-phase flow with heating in parallel channels is prone to maldistribution, which can result in sub-optimal performance and, in some cases, permanent damage to the system. This challenge requires accurate flow modeling in parallel channels to mitigate or design against the adverse effect of two-phase flow maldistribution. The nonlinear nature of the multiphase flow model can yield multiple solutions for the same operating condition, creating significant challenges in predicting flow distribution. This study addresses this challenge by applying the entropy balance analysis and the conservation of mass, momentum, and energy to predict two-phase flow distribution in two thermally isolated parallel channels with a numerical model. Our model predictions and experiments show that equally distributed flow can become severely maldistributed with a decrease in flow rate, accompanied by a significant (>30%) change in the entropy generation rate. We show that the entropy balance analysis can distinguish between stable and unstable flows and identify the most feasible flow distribution in thermally decoupled parallel channels.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":" 32","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141131921","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

Vibration-triggered spreading of nanofluid drops 振动触发的纳米流体液滴扩散

Physics of Fluids Pub Date : 2024-05-01 DOI: 10.1063/5.0205785

Schon Fusco, Lingyue Liu, M. Cabrerizo-Vílchez, E. Koos, M. Rodríguez-Valverde

引用次数: 0

Control of cylinder wake using oscillatory morphing surface 利用振荡变形表面控制气缸尾流

Physics of Fluids Pub Date : 2024-05-01 DOI: 10.1063/5.0208868

Lingwei Zeng, T. H. New, Hui Tang

引用次数: 0

Effects of microscopic pore-throat structure on gas–liquid relative permeability: Porous media construction and pore-scale simulation 微观孔喉结构对气液相对渗透性的影响：多孔介质构造与孔隙尺度模拟

Physics of Fluids Pub Date : 2024-05-01 DOI: 10.1063/5.0205591

B. Wei, Yang Zhang, Jian Hou, Dong Zhao, Yongge Liu, Zhixin Guo, Xiaoke Yang

引用次数: 0

Dark-soliton asymptotics for a repulsive nonlinear system in a baroclinic flow 巴氏流中斥力非线性系统的暗索利子渐近论

Physics of Fluids Pub Date : 2024-05-01 DOI: 10.1063/5.0213090

Xi-Hu Wu, Yi-Tian Gao, Xin Yu

{"title":"Dark-soliton asymptotics for a repulsive nonlinear system in a baroclinic flow","authors":"Xi-Hu Wu, Yi-Tian Gao, Xin Yu","doi":"10.1063/5.0213090","DOIUrl":"https://doi.org/10.1063/5.0213090","url":null,"abstract":"In geophysical hydrodynamics, baroclinic instability denotes the process in which the perturbations draw the energy from the mean flow potential power. Researchers focus their attention on the baroclinic instability in the Earth's atmosphere and oceans for the meteorological diagnosis and prediction. Under investigation in this paper is a repulsive nonlinear system modeling the marginally unstable baroclinic wave packets in a baroclinic flow. With respect to the amplitude of the baroclinic wave packet and correction to the mean flow resulting from the self-rectification of the baroclinic wave, we present a Lax pair with the changeable parameters and then derive the N-dark-dark soliton solutions, where N is a positive integer. Asymptotic analysis on the N-dark-dark solitons is processed to obtain the algebraic expressions of the N-dark-dark soliton components. We find that the obtained phase shift of each dark-dark soliton component is relevant with the N − 1 spectral parameters. Furthermore, we take N = 3 as an example and graphically illustrate the 3-dark-dark solitons, which are consistent with our asymptotic-analysis results. Our analysis may provide the explanations of the complex and variable natural mechanisms of the baroclinic instability.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":"40 16","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141142782","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

Primary breakup of a jet coupled with vortex-induced string cavitation in a fuel injector nozzle 喷油器喷嘴中的喷流初级破裂与涡流诱导串空化耦合

Physics of Fluids Pub Date : 2024-05-01 DOI: 10.1063/5.0204584

Wei Guan, Yunlong Huang, Zhixia He, Genmiao Guo, Chuqiao Wang, Dominique Thévenin

{"title":"Primary breakup of a jet coupled with vortex-induced string cavitation in a fuel injector nozzle","authors":"Wei Guan, Yunlong Huang, Zhixia He, Genmiao Guo, Chuqiao Wang, Dominique Thévenin","doi":"10.1063/5.0204584","DOIUrl":"https://doi.org/10.1063/5.0204584","url":null,"abstract":"Fuel jet primary breakup strongly depends on the in-nozzle cavitation phenomena found in the high-pressure fuel injector nozzle. Nevertheless, limited attention has been paid to the mechanism of fuel jet primary breakup induced by in-nozzle vortex-induced string-type cavitation. This study involves simulations of in-nozzle string cavitating flow and simultaneously near-nozzle jet primary breakup process using large eddy simulation and volume of fluid, aiming at revealing the effects of string cavitation on jet primary breakup. The numerical results are in good agreement with experimental data in terms of string cavitation intensity, interfacial topology of jet, and spray spreading angle. The numerical investigations indicate that the external surface of the jet experiences Kelvin–Helmholtz instabilities, which results in the development of circumferential and axial surface waves at the fuel film surface. Subsequently, the fuel film surface undergoes progressive wrinkling, resulting in its breakup into multiple ligaments and large droplets. On the internal side of the jet, back-suction of air caused by negative pressure and its interaction with cavitation vapor at the core of the jet lead to the collapse of vapor bubbles. The resulting pressure waves and micro-jets facilitate the detachment of liquid sheets from the internal surface of the jet. Analysis of the enstrophy transport equation indicates that the driving mechanism behind string cavitation jet breakup further downstream is the baroclinic torque term, which is responsible for the generation of a cascade of smaller vortical structures. This effect dominates over vortex stretching and dilatation terms.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":"77 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141134900","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

Mode transition of a film fluttering in a circular cylinder wake 圆筒形尾流中薄膜飘动的模式转换

Physics of Fluids Pub Date : 2024-05-01 DOI: 10.1063/5.0210731

Fan Duan, Jinjun Wang

{"title":"Mode transition of a film fluttering in a circular cylinder wake","authors":"Fan Duan, Jinjun Wang","doi":"10.1063/5.0210731","DOIUrl":"https://doi.org/10.1063/5.0210731","url":null,"abstract":"As a representative model in the investigation into fluid–structure coupling, a flexible film interacting with the wake of a circular cylinder involves intricate patterns of both solid motion and fluid evolution. Recent investigations have found that the interactions could be either periodic or aperiodic in experiments; the latter, however, is often overlooked. In this work, the irregular aperiodic flutter of a flexible film behind a circular cylinder is investigated experimentally. It is determined that the irregular flutter intermittently exhibits transient quasi-periodic mode and aperiodic mode. The former is accompanied by the large-scale vortices alternatively formed against the film surfaces, while the latter is associated with vortices formed downstream of the film's trailing edge, so that the whole film is enveloped by the extended shear layers. In order to separate the data individually pertaining to each of the two modes from the whole dataset, a motion-mode recognition method is proposed, and then conditional statistics of flow fields are achieved. The quasi-periodic mode corresponds to more intense velocity fluctuations in the wake, while in the aperiodic mode, the observed localized instability of shear layers induces an increase in the local streamwise velocity fluctuation.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":"28 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141142540","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

Intermittency, an inevitable feature for faster convergence of large eddy simulations 间歇性是大涡度模拟更快收敛的必然特征

Physics of Fluids Pub Date : 2024-05-01 DOI: 10.1063/5.0202514

Marcel Bock, Khaled Yassin, H. Kassem, Johannes Theron, L. J. Lukassen, Joachim Peinke

引用次数: 0

Unsupervised contrastive learning: Shale porosity prediction based on conventional well logging 无监督对比学习：基于常规测井的页岩孔隙度预测

Physics of Fluids Pub Date : 2024-05-01 DOI: 10.1063/5.0206449

Lu Qiao, Shengyu Yang, Qinhong Hu, Huijun Wang, Taohua He

{"title":"Unsupervised contrastive learning: Shale porosity prediction based on conventional well logging","authors":"Lu Qiao, Shengyu Yang, Qinhong Hu, Huijun Wang, Taohua He","doi":"10.1063/5.0206449","DOIUrl":"https://doi.org/10.1063/5.0206449","url":null,"abstract":"Porosity is a pivotal factor affecting the capacity for storage and extraction in shale reservoirs. The paucity of labeled data in conventional well logs interpretation and supervised learning models leads to inadequate generalization and diminished prediction accuracy, thus limiting their effectiveness in precise porosity evaluation. This study introduces a contrastive learning – convolutional neural network (CL-CNN) framework that utilizes CL for pretraining on a vast array of unlabeled data, followed by fine-tuning using a traditional CNN on a curated set of labeled data. Applied to the Subei Basin in Eastern China, the framework was tested on 130 labeled data and 2576 unlabeled data points from well H1. The results indicate that the CL-CNN framework outperforms traditional CNN-based supervised learning and other machine learning models in terms of prediction accuracy for the dataset under consideration. Furthermore, it demonstrates the potential for extensive porosity assessment across different logged depths. Due to its efficacy and ease of use, the proposed framework is versatile enough for application in reservoir evaluation, engineering development, and related fields. The innovative contribution of this research is encapsulated in its unique methodology and procedural steps for the accurate prediction of shale reservoir porosity, thus significantly enriching the existing body of knowledge in this domain.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":"67 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141031536","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

Dynamics of tandem bubble interaction near tissue 组织附近串联气泡相互作用的动力学原理

Physics of Fluids Pub Date : 2024-05-01 DOI: 10.1063/5.0201811

Junjie Zhao, Jingzhu Wang, Shunxiang Cao

引用次数: 0