International Journal of Multiphase Flow最新文献

{"title":"Real-time automatic flow regime classification and mapping for vertical pipes using dynamic pressure signals","authors":"Umair Khan ,&nbsp;William Pao ,&nbsp;Karl Ezra Pilario ,&nbsp;Nabihah Sallih ,&nbsp;Muhammad Sohail ,&nbsp;Huzaifa Azam","doi":"10.1016/j.ijmultiphaseflow.2025.105252","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105252","url":null,"abstract":"<div><div>Accurate flow regime identification is essential for modeling two-phase flow systems, but the literature on real-time applications in vertical pipes is scarce. This work aims to develop a real-time, automated, data-driven flow regime classifier for vertical pipes using dynamic pressure signals. These signals were collected using a numerical model to represent three distinct flow regimes—slug, churn, and annular—in a 3-inch vertical pipe. Features were then extracted from these signals using Discrete Wavelet Transform (DWT). To optimize classification performance, twelve dimensionality reduction techniques were evaluated, followed by the application of an AutoML framework to identify the most effective machine learning classifier among K-Nearest Neighbors (KNN), Artificial Neural Networks, Support Vector Machines (SVM), Gradient Boosting, Random Forest, and Logistic Regression, with hyperparameter tuning incorporated. Kernel Fisher Discriminant Analysis (KFDA) demonstrated the best clustering performance, while KNN emerged as the top classifier with 90.2% accuracy and excellent repeatability. Leveraging DWT, KFDA, and KNN, a virtual flow regime map was constructed, enabling real-time flow regime identification with a moving window of pressure signals. Verification of the model using a 50.8 mm (2-inch) diameter pipe at different locations confirmed its robustness and scalability. In the final stage, a unified flow regime map was developed for both horizontal and vertical pipes, achieving 100% training and 92.5% testing accuracy using DWT, KFDA, and ANN. The proposed workflow represents a significant step forward in automating flow regime identification, enabling its application to opaque pipes fitted with pressure sensors for flow assurance and monitoring in process industries.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"189 ","pages":"Article 105252"},"PeriodicalIF":3.6,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143823473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New regimes and their spraying characteristics of electrohydrodynamic atomization","authors":"Yin Guan ,&nbsp;Yanxiu Sha ,&nbsp;Bin He ,&nbsp;Jingze Zheng ,&nbsp;Yihang Lei ,&nbsp;Yang Liu ,&nbsp;Wuxing Lai ,&nbsp;YongAn Huang","doi":"10.1016/j.ijmultiphaseflow.2025.105250","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105250","url":null,"abstract":"<div><div>Electrohydrodynamic (EHD) atomization is a highly useful regime of EHD spraying, which has been applied to the production of three-dimensional ultra-thin membrane structures and also the removal of high heat flux called electrospray cooling. However, the rapidly changing liquid atomization behavior under the impact of a high electrostatic potential is so complicated that many aspects of the atomization morphology are not completely comprehended. In this work, we conducted an experimental study on EHD atomization under three key operating parameters including applied voltage, flow rate, and nozzle height, where nozzle height is a variable that was barely investigated in previous EHD spraying work. Seven distinct spraying regimes, namely Spindle, Pulsating Jet, Rotating Atomization, Pulsating Atomization, Stable Atomization, Tilted Atomization, and Oscillating Jet are observed, where Rotating Atomization and Pulsating Atomization are two newly discovered regimes that have not been discussed before. We use the electric Bond number and dimensionless flow rate to analyze and explain the variations of spraying profile and regime, Taylor cone profile, liquid jet breakup length, liquid jet rotating and pulsating frequency, liquid jet atomization angle and atomization area of the atomization process. Especially, the characteristics of the two newly discovered atomization regimes are comprehensively examined and compared with those of the Stable Atomization regime, which provide some new insights into the complex and variable EHD atomization phenomena.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"189 ","pages":"Article 105250"},"PeriodicalIF":3.6,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143839432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-physical field cross-scale simulation of brine freezing process in microchannel fluid flow considering suspended ice crystals","authors":"Ji Zhang,&nbsp;Jing Yuan,&nbsp;Han Yuan","doi":"10.1016/j.ijmultiphaseflow.2025.105254","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105254","url":null,"abstract":"<div><div>Freeze method using microchannel systems offers high separation efficiency but faces challenges in controlling ice blockage caused by suspended crystals and wall dendrite growth. This study develops a dynamic phase-change model integrating the Phase Field Method (PFM) and Lattice Boltzmann Method (LBM) to investigate crystallization in brine microchannels under flow conditions. A novel multiscale computational strategy is proposed: phase and concentration fields are resolved at the mesoscale near solid-liquid interfaces, while macroscopic temperature fields are derived from their averaged values, significantly reducing grid coupling iterations and enhancing computational efficiency. Experiments using a cryo-crystallization system validate the model, demonstrating excellent agreement in ice morphology, solute distribution, and blockage dynamics. Results reveal that suspended ice crystals accelerate microchannel blockage by 2.5-fold compared to scenarios without them, driven by synergistic interactions between suspended crystals and wall dendrites. The PFM-LBM framework provides critical insights into phase transitions, solute migration, and flow-thermal coupling, offering theoretical guidance for optimizing microchannel-based freeze desalination systems and addressing ice-related challenges in broader cryogenic applications.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"189 ","pages":"Article 105254"},"PeriodicalIF":3.6,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143850694","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation into the deformation process of water droplets bag breakup in airflow with elevated temperatures","authors":"Ke Zheng ,&nbsp;Yufei Zhu ,&nbsp;Zhiwen Gan","doi":"10.1016/j.ijmultiphaseflow.2025.105232","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105232","url":null,"abstract":"<div><div>Experimental and theoretical studies of droplet deformation under airflow-droplet temperature differentials remain scarce. This investigation examines the deformation process of water droplet bag breakup at five different temperatures (278 K, 303 K, 323 K, 348 K, and 368 K) in the airflow temperature range from 300 K to 493 K. Results demonstrate that both droplet and airflow temperatures significantly influence deformation dynamics. The effect of heat exchange between the airflow and droplet on the droplet deformation process arises from the combined effect of convective heat transfer and evaporation. It is found that the results of existing empirical and theoretical models for droplet deformation, such as the DDB (Drop Deformation Breakup) model, do not agree well with experimental data in this investigation due to unaccounted heat exchange effects. Based on the DDB model, an improved model considering windward-side heat transfer and evaporation is proposed, which significantly reduces the prediction errors of the droplet deformation diameter with time. Energy analysis further quantifies the contributions of aerodynamic forces and heat exchange to droplet energy evolution during deformation, validating the droplet deformation mechanism with heat exchange. In this investigation, the timescale of droplet deformation is sufficiently short to render heat exchange effects on droplet average temperature variations and evaporation-induced mass loss negligible. Both theoretical and experimental results confirm that heat exchange primarily modulates droplet surface energy, thereby influencing deformation dynamics.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"188 ","pages":"Article 105232"},"PeriodicalIF":3.6,"publicationDate":"2025-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143785203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"50 Years of International Journal of Multiphase Flow: Experimental methods for dispersed multiphase flows","authors":"Laura Villafañe ,&nbsp;Alberto Aliseda ,&nbsp;Steven Ceccio ,&nbsp;Paolo Di Marco ,&nbsp;Nathanaël Machicoane ,&nbsp;Theodore J. Heindel","doi":"10.1016/j.ijmultiphaseflow.2025.105239","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105239","url":null,"abstract":"<div><div>The presence of one or more dispersed phases in a continuous carrier flow adds challenges to the experimental characterization of multiphase flows. Numerous experimental techniques have been developed over the past 50 years that overcome the challenges introduced by the optical opacity and the presence of phase interfaces, some providing global quantities while others offering local or spatial information of the distinct phases. This paper reviews several experimental techniques for dispersed multiphase flow measurements that are relevant to various types of flows with a gaseous, solid, or liquid phase dispersed in a gas or liquid carrier, and that are considered important by the authors based on their collective experience. Additionally, the paper highlights promising areas of ongoing development aimed at advancing multiphase flow measurement techniques.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"189 ","pages":"Article 105239"},"PeriodicalIF":3.6,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143843265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On grid-independency of CFD-DEM simulations of cluster-induced turbulence","authors":"Behrad Esgandari,&nbsp;Simon Schneiderbauer","doi":"10.1016/j.ijmultiphaseflow.2025.105223","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105223","url":null,"abstract":"<div><div>We present a comparative study on the influence of three different particle (data) mapping methods on various one-point and two-point cluster-induced turbulence (CIT) statistics in an unbounded fluidization system. These methods include the particle centroid method (PCM), the divided particle volume method (DPVM), and a newly proposed implementation of Gaussian kernel method referred to as GaussFace method. In PCM method, the entire particle data is allocated to the cell, in which the particle centroid is located. However, in DPVM, the particle data is subdivided into smaller volumes using a satellite point method, allowing the distribution of particle properties among the cells associated with the satellite points. We performed simulations of dilute and dense systems at grid sizes between 2.22<span><math><mrow><msub><mrow><mi>d</mi></mrow><mrow><mi>p</mi></mrow></msub><mo>−</mo><mn>8</mn><mo>.</mo><mn>88</mn><msub><mrow><mi>d</mi></mrow><mrow><mi>p</mi></mrow></msub></mrow></math></span> and two smoothing characteristic sizes. Our results reveal that solely using GaussFace method, which is based on distributing particle data to surrounding cells employing a Gaussian kernel, leads to a smoother particle field compared to the PCM and DPVM. Furthermore, we find that grid-independent results can only be obtained by GaussFace method together with subsequent smoothing. We also observe that the grid-independence criterion identified for the dilute system is also valid for the dense system. In addition, comparing two different methods of separating the spatially correlated and uncorrelated particle velocity components reveals that the commonly adopted fixed filter approach grossly underestimates the granular temperature in the dilute regions. The findings of our study can serve as a reference for obtaining high-resolution CFD-DEM results, which, in turn, can be used to develop coarse-grid models.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"188 ","pages":"Article 105223"},"PeriodicalIF":3.6,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143785204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Topological change of a hollow droplet impacting onto a cylindrical super-hydrophobic target: A numerical study","authors":"Linkai Yang ,&nbsp;Longmin Tang ,&nbsp;Guangzhao Zhou","doi":"10.1016/j.ijmultiphaseflow.2025.105227","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105227","url":null,"abstract":"<div><div>In this paper, we numerically investigate the dynamics of a hollow droplet impacting onto a small super-hydrophobic cylinder. Four distinct regimes are identified based on the topological changes experienced by the droplet during impact: direct bounce, break-retract, break-break, and rim break. The transitions between these regimes are discussed with respect to dimensionless parameters such as the Weber number and the droplet-to-target diameter ratio. Additionally, we propose theoretical predictions for these regime transitions, which show reasonable agreement with our numerical results. This study provides insights into the dynamics of hollow droplets impacting on rough surfaces and has potential applications in altering the topology of hollow and other compound droplets.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"188 ","pages":"Article 105227"},"PeriodicalIF":3.6,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143800151","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Single cavitation bubble dynamics in a confined planar flow","authors":"Dominik Gebensleben,&nbsp;Fabian Reuter,&nbsp;Claus-Dieter Ohl","doi":"10.1016/j.ijmultiphaseflow.2025.105224","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105224","url":null,"abstract":"<div><div>Single cavitation bubbles are nucleated in a planar flow within a narrow liquid filled gap to understand the effect of velocity gradients on the cavitation bubble collapse. The cavitation bubble is created close to one of the boundaries with a pulsed laser and near the center of the gap. Overall, the flow transports the center of mass of the bubble and induces a non-axisymmetric collapse that affects the direction and strength of the liquid jet. The water flow velocity is varied up to 18 m/s and resulting in shear rates of up to <span><math><mrow><mn>4</mn><mi>⋅</mi><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>5</mn></mrow></msup><mspace></mspace></mrow></math></span>1/s. Already at a moderate flow velocity of a few meter per seconds, the bubble looses its cylindrical symmetry when expanding and collapsing near the boundary. Additionally, the downstream region of the bubble lifts away from the boundaries, adding a thin layer of liquid between the jet and the wall. A bubble expanding in the center of the gap also looses its cylindrical symmetry that results in much weaker or no jets impacting on the boundaries. Overall, with increasing flow velocity the lifetime of the bubble is shortened, and its first collapse is occurring further away from the boundary.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"188 ","pages":"Article 105224"},"PeriodicalIF":3.6,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143800150","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unlocking the dynamics of complex instability mechanisms in developing gravity-driven slug flows","authors":"Shahriyar G. Holagh,&nbsp;Wael H. Ahmed","doi":"10.1016/j.ijmultiphaseflow.2025.105230","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105230","url":null,"abstract":"<div><div>Slug flow stability stands as a critical frontier in two-phase flow research, with limited focus on the complex dynamics governing unstable gravity-driven slug flows in developing regions. Despite decades of research, several uncertainties persist, particularly regarding the complex mechanisms driving the flow instabilities. These uncertainties encompass the systematic classification of instabilities, their interdependence or isolation, their persistence or transience, and whether they exhibit chaotic or periodic behavior. Additionally, questions remain about their temporal dynamics—whether they evolve rapidly or gradually—their relative intensity, and their spatiotemporal propagation as they interact with overall flow development. Moreover, it remains unclear whether gravity induces new instability modes, what distinct characteristics these modes exhibit, and how gas density modulate instability dynamics. Furthermore, can a fully stabilized flow state ever be attained, or is it an elusive ideal? Most critically, how can one effectively diagnose instabilities, track their progression, and pinpoint stabilization onset in real time under operational constraints? Addressing these questions has been historically challenging due to the lack of a robust framework capable of simultaneously analyzing the inherent multi-layered complexities of two-phase flow instabilities. To overcome this limitation and provide explanations for the above-mentioned questions, we introduce a novel AI-assisted, data-driven, scale-independent spatiotemporal-spectral analysis framework, integrating advanced signal processing techniques—Recurrence Qualification Analysis, Fast Fourier Transform, and Discrete and Continuous Wavelet Transforms—to analyze void fraction signals captured at four spatial locations in air- and CO₂-water gravity-driven slug flows. High-speed imaging complements the analysis, offering visual insights into transient instability mechanisms. The analysis also charts an instability map, systematically classifying instability mechanisms while depicting their interconnections. A Convolutional Neural Network extracts features, transforming the analysis framework into a fast-response, real-time diagnostic and predictive tool, achieving an accuracy of <span><math><mo>∼</mo></math></span>96 %. This represents a breakthrough in diagnosing instabilities, tracking their evolution, and identifying the onset of stabilization within slug flows. By bridging analytical precision with real-time capabilities, this data-driven, scale-independent framework establishes a new benchmark for the analysis and control of complex two-phase flow systems of varying dimensions.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"188 ","pages":"Article 105230"},"PeriodicalIF":3.6,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143792296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improved dynamics, atomization, and vaporization models for liquid ammonia spray simulations under diverse ambient conditions","authors":"Yanzhi Zhang,&nbsp;Chentao Chu,&nbsp;Zihe Liu,&nbsp;Ming Jia","doi":"10.1016/j.ijmultiphaseflow.2025.105225","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105225","url":null,"abstract":"<div><div>The use of liquid ammonia as fuel in energy conversion devices presents attractive prospects due to its advantage of zero carbon dioxide emissions. However, the dynamics, atomization, and phase change behaviors of liquid ammonia spray are significantly different from those of conventional gasoline and diesel fuels because of its unique physical properties (e.g., low boiling point, low viscosity, and high latent heat of vaporization), making an accurate simulation of liquid ammonia spray under a wide range of ambient conditions highly challenging. To address this, improved drag, atomization, and vaporization sub-models are proposed in this study to more precisely simulate the ammonia spray process. The effects of finite viscosity and droplet distortion (ranging from prolate spheroid to oblate spheroid) are considered to replicate the drag and vaporization characteristics of ammonia spray. Additionally, an updated flash-boiling atomization model is introduced to reproduce the thermal breakup process by introducing the influence of liquid viscosity in the breakup dispersion equation. The bubble growth rate within the liquid droplet is also enhanced using the latest theories. The validity of the improved models is evaluated through comparisons of experiments and large-eddy simulation (LES) of ammonia spray under typical evaporating and flash-boiling conditions. It is found that the new drag model predicts a lower drag coefficient and a higher evaporation rate than the traditional model under the evaporating conditions and can more accurately reproduce the experimental data. Moreover, the improved flash-boiling atomization model, coupled with the new drag model, demonstrates the highest accuracy in predicting spray dynamics and morphology of flash-boiling sprays compared to other models. After extensive validations, the improved spray models can effectively reproduce the atomization and vaporization characteristics of liquid ammonia sprays across a wide range of operating conditions.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"188 ","pages":"Article 105225"},"PeriodicalIF":3.6,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143785202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}