{"title":"Experimental and modelling study of creaming in concentrated emulsions under centrifugation","authors":"Djibrilla Mounkaila Noma, Noureddine Lebaz, Khadija Sall, Nida Sheibat-Othman","doi":"10.1016/j.ijmultiphaseflow.2025.105380","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105380","url":null,"abstract":"<div><div>Monitoring and modelling emulsion creaming/sedimentation is essential in several engineering applications. However, when dealing with concentrated emulsions, further challenges appear due to complex interactions that make their investigation tricky. In this study, we develop and validate a method that combines experiments and modelling to quantify the creaming kinetics in dense oil-in-water emulsions. Centrifugation is used to accelerate phase separation. Glycerol is added to the continuous phase to modify its refractive index, making it closer to that of the dispersed phase, which increases light transmission in concentrated emulsions and enables tracking of droplet creaming by light transmission measurements. A one-dimensional convection–diffusion model is evaluated against experimental data using various hindered-settling velocity correlations. Dimensionless analysis supports key modelling assumptions and elucidates the observed dynamics. Computational Fluid Dynamics simulations are also performed using the Euler–Euler method, and the results are compared to the experiments and the convection–diffusion model predictions.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"193 ","pages":"Article 105380"},"PeriodicalIF":3.8,"publicationDate":"2025-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144830384","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":"Nonlinear ultrasound propagation through coated microbubbles:Influence of shell constitutive laws","authors":"Mayuko Ogi , Ryoki Kawahata , Georges Chabouh , Tetsuya Kanagawa","doi":"10.1016/j.ijmultiphaseflow.2025.105392","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105392","url":null,"abstract":"<div><div>The use of microbubbles encapsulated by membranes as contrast agents has generated considerable interest owing to their potential to enhance image resolution. Numerous theoretical studies have investigated the mechanics of these membranes, revealing that they play a crucial role in microbubble oscillation, for example, by significantly increasing attenuation. While several membrane materials have been examined for their mechanical properties, theoretical studies on the behavior of multiple microbubbles remain limited, despite their frequent use in both practical and experimental contexts. This gap highlights the importance of understanding ultrasound propagation through liquids containing multiple microbubbles. In this study, the foundational work of Tsiglifis and Pelekasis (J. Acoust. Soc. Am., <strong>123,</strong> 2008), which analyzed the oscillation of a single microbubble, is extended to examine ultrasound propagation through multiple microbubbles using three distinct constitutive laws. These laws describe varying stress–strain relationships that characterize membrane elasticity. The singular perturbation method was applied to the governing equations for bubbly liquids to derive a one-dimensional nonlinear wave equation that captures the second-order ultrasound nonlinearity. The analysis shows that variations in the constitutive laws significantly affect the nonlinearity of ultrasound propagation. The findings suggest potential applications in enhancing the accuracy of ultrasound models and guiding the development of new contrast agents.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"193 ","pages":"Article 105392"},"PeriodicalIF":3.8,"publicationDate":"2025-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144907990","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}
Vasco O. Duke W. , Manoj Paudel , Jacob Keltz , Jacob A. McFarland
{"title":"Deformation and acceleration of small droplets at high-speed conditions","authors":"Vasco O. Duke W. , Manoj Paudel , Jacob Keltz , Jacob A. McFarland","doi":"10.1016/j.ijmultiphaseflow.2025.105372","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105372","url":null,"abstract":"<div><div>Shock-driven droplet breakup occurs in various physical systems and plays a critical role in emergent high-speed flight applications such as droplet combustion in rotating detonation engines (RDEs) and droplet impacts on hypersonic vehicles. Droplets interact with strong shock waves in these applications, and the high post-shock gas velocity and temperature lead to rapid droplet acceleration, evaporation, and breakup through various hydrodynamic instabilities. Accurate prediction of the breakup process is essential in these applications and theory-based models are required to cover the large parameter space encountered. In order to model the growth of hydrodynamic instabilities on the droplet, the acceleration and droplet shape must be known first, requiring accurate prediction of both deformation and drag. Previous work has largely focused on large droplets at lower shock strengths, where acceleration and evaporation are much slower. Here, the dynamics of small droplets accelerated by strong shock waves are explored up to the onset of breakup, focusing on droplet size, Mach number, and evaporation effects on the deformation and acceleration.</div><div>Shock tube experiments are conducted for a wide range of parameters including droplet size, shock strength, and liquid properties. Incident shock wave Mach numbers of 1.35 - 2.1 are used with micron-scale droplets with diameters from <span><math><mrow><mo>∼</mo><mn>50</mn></mrow></math></span> to <span><math><mrow><mn>200</mn><mrow><mo>[</mo><mi>μ</mi><mi>m</mi><mo>]</mo></mrow></mrow></math></span>. Various fluids (water, dodecane, and acetone) were studied yielding Weber numbers from <span><math><mrow><mo>∼</mo><mn>100</mn><mtext>–</mtext><mn>6000</mn></mrow></math></span>. Droplet deformation and position are measured with sub-micrometer spatial resolution and sub-microsecond temporal resolution. New modifications to the Taylor Analogy Breakup model are presented with modified drag correlations accounting for deformation and Mach number effects to accurately capture the droplet dynamics. The results are compared with previous millimeter-droplet breakup studies, finding that bulk droplet deformation and drag are captured by the new models over a wide range of conditions. Evaporation was not observed to effect these processes, even for the smallest droplets. However, small droplets are shown to exhibit significantly less hydrodynamic instability growth than large droplets, which display a larger departure in trajectory from the model at late times.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"193 ","pages":"Article 105372"},"PeriodicalIF":3.8,"publicationDate":"2025-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144828142","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":"Analysis of compressibility effects on multiscale cavitating flow in the nozzle using Eulerian-Lagrangian method","authors":"Ziyang Wang , Demin Liu , Xianwu Luo","doi":"10.1016/j.ijmultiphaseflow.2025.105412","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105412","url":null,"abstract":"<div><div>A compressible two-way coupling Eulerian-Lagrangian (E-L) method is developed to investigate the compressibility effects on multiscale cavitating flow inside a nozzle. The compressible Navier-Stokes (N-S) equations and compressible Rayleigh-Plesset (R-P) equation are introduced to fully describe compressible effects. Compared with the traditional incompressible E-L method, the compressible E-L method more accurately simulates the characteristics of unsteady cavitating flow, including cavity shedding frequency, mean cavity length and bubble size distribution. Results show that compressibility exacerbates the instability of cloud cavitation, causing macroscopic cavities to break into microbubbles more frequently, further increasing the number of bubbles and expanding their distribution. Further analysis reveals that compressibility effect amplifies mid- and high-frequency bands of pressure fluctuations, especially in the cavity tailing region where only discrete bubbles exist. Additionally, the compressible E-L approach avoids the problem of pseudo-pressure pulsation caused by computational simplification in the incompressible E-L approach. The variation of velocity divergence is driven not only by water-vapor mass transfer but also by density changes in compressible cavitating flow. The temperature distribution indicates that low temperature always exists inside the attached cavity due to evaporation and heat absorption. Strong temperature fluctuation, reaching up to 1.5 K, occurs during the upstream movement of the re-entrant jet and the cavity shedding process. The Mach number distribution illustrates that transient supersonic flow appears only in the wake of the attached sheet cavities and at the shedding cloud interface. These findings provide deeper insights into the multiscale cloud cavitation instability induced by compressibility effects.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"193 ","pages":"Article 105412"},"PeriodicalIF":3.8,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144831505","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":"Three-dimensional simulation on electric field assisted alignment of cellulose Nanofibrils in focusing flow","authors":"Hidemasa Takana , Ryo Sato , Takumi Usui","doi":"10.1016/j.ijmultiphaseflow.2025.105413","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105413","url":null,"abstract":"<div><div>Cellulose nanofibril behavior in the electric field-assisted flow-focusing channel was clarified by solving the equation of motion for individual fibrils in the flow to fabricate strong cellulose filaments. The electric field effectively improved the alignment of shorter fibrils, whereas longer fibrils were better aligned by the hydrodynamic effect. The overall alignment of fibrils with a length distribution was increased by aligning the shorter fibrils with the assistance of an electric field. The electric field plays a crucial role in aligning the fibrils in the flow-core region, where alignment by shear flow cannot be expected.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"193 ","pages":"Article 105413"},"PeriodicalIF":3.8,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144828140","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}
Jie Sun , Fanhao Meng , Ziqiang Wang , Xingjie Zeng , Yi Wen , Shuai Wang , Yingda Lu , Nana Sun , Weidong Li
{"title":"Drag reduction performance in transportation of thermally produced heavy oil by self-generating foam injection","authors":"Jie Sun , Fanhao Meng , Ziqiang Wang , Xingjie Zeng , Yi Wen , Shuai Wang , Yingda Lu , Nana Sun , Weidong Li","doi":"10.1016/j.ijmultiphaseflow.2025.105389","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105389","url":null,"abstract":"<div><div>This work proposes a novel approach utilizing an oil-resistant, thermally stable self-generating foam system to achieve boundary lubrication drag reduction in thermal heavy oil transportation, focusing on the drag reduction characteristics of non-Newtonian self-generating foam and Newtonian oil phases under horizontal pipe co-flow conditions. Experiments were conducted in a 12-m-long, 25-mm-inner-diameter horizontal borosilicate glass pipe with roughened walls, measuring pressure gradients for co-flowing high-viscosity oil and foam at superficial velocities of 0.12–0.65 m/s (oil) and 0.06–0.63 m/s (foam). High-speed imaging identified stratified flow (ST) and eccentric core annular flow (ECAF) as dominant regimes across tested conditions. A three-zone two-phase model was developed for horizontal foam-oil flows, integrating the Carreau-Yasuda rheology of self-generated foam at 60°C. The model demonstrates strong agreement with experimental data over broad operational ranges, confirming that full oil core encapsulation by foam determines the critical foam injection volume fraction for maximum drag reduction. Additionally, optimal oil transport efficiency was linked to specific oil core-to-pipe diameter ratios.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"193 ","pages":"Article 105389"},"PeriodicalIF":3.8,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144829741","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}
Andrey V. Cherdantsev, Sergey V. Isaenkov, Dmitry M. Markovich
{"title":"Controlling large-scale waves in downward annular flow far from the inlet","authors":"Andrey V. Cherdantsev, Sergey V. Isaenkov, Dmitry M. Markovich","doi":"10.1016/j.ijmultiphaseflow.2025.105415","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105415","url":null,"abstract":"<div><div>Disturbance waves are the key element of annular gas-liquid flows. They produce liquid entrainment and affect heat and mass transfer in the flow. Ability to control (initiate or regularize) them can be useful for optimization of industrial equipment or carrying out in-depth experimental studies. Here we continue our earlier works wherein the possibilities of controlling the disturbance waves by means of inlet forcing were investigated. In the present study, we employ different conditions, including larger pipe diameter, longer distance from the inlet and different range of gas speeds. The results confirm all the conclusions made earlier, widening their range of applicability and improving our understanding of the important factors affecting capabilities and limitations of flow control. In particular, it was found that the flow control works at relatively large distances (90 pipe diameters) from the inlet without showing any signs of decay. Even in absence of gas flow, it is possible to create large-scale waves on thick films which remain regular over the long distance. Spatiotemporal dynamics of small-scale waves produced by the large waves in these conditions has unexpected similarity to that of disturbance waves.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"193 ","pages":"Article 105415"},"PeriodicalIF":3.8,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144831506","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}
Carolina C. Rodrigues , Paul A.D. Maldonado , Gabriel D. Garcia , Eduardo N. dos Santos , Moises A. Marcelino Neto , Alain Liné , Rigoberto E.M. Morales
{"title":"3D (2D space and time) experimental analysis of vertical slug flow – part 1: Air - Water","authors":"Carolina C. Rodrigues , Paul A.D. Maldonado , Gabriel D. Garcia , Eduardo N. dos Santos , Moises A. Marcelino Neto , Alain Liné , Rigoberto E.M. Morales","doi":"10.1016/j.ijmultiphaseflow.2025.105386","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105386","url":null,"abstract":"<div><div>Slug flow is one among the different flow patterns that two-phase flows can assume and is composed of a Taylor bubble and a liquid slug. The transient and intermittent behaviors of this kind of flow demand that its characteristics must be determined. In this study, an experimental characterization of the vertical upward slug flow in a 0.050-m ID, 15-m-long vertical pipe was developed. Air-water experiments were carried out, with both the gas and the liquid superficial velocities ranging from 0.4 to 3.5 m/s. Four ring conductance sensors and one capacitive wire-mesh sensor were deployed in the test sections to measure the characteristics parameters, namely the Taylor bubble velocity, the unit-cell frequency, the Taylor bubble and the liquid slug lengths and gas fractions, with the aim of evaluating the distribution and evolution of each parameter. A comparison with the unit-cell model showed deviations in gas fraction and pressure drop predictions that originated from simplified assumptions such as a constant liquid film thickness and the absence of dispersed bubbles in the liquid film.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"193 ","pages":"Article 105386"},"PeriodicalIF":3.8,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144827631","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}
Wei Li (李伟) , Haoming Li (李昊明) , Mingjiang Liu (刘明江) , Leilei Ji (季磊磊) , Yu Long (龙雨) , Xiwei Xu (徐希魏) , Ramesh K. Agarwal
{"title":"Application of the Wray-Agarwal turbulence model in the numerical simulation of unsteady cavitation around a three-dimensional hydrofoil","authors":"Wei Li (李伟) , Haoming Li (李昊明) , Mingjiang Liu (刘明江) , Leilei Ji (季磊磊) , Yu Long (龙雨) , Xiwei Xu (徐希魏) , Ramesh K. Agarwal","doi":"10.1016/j.ijmultiphaseflow.2025.105395","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105395","url":null,"abstract":"<div><div>This research investigates the performance of the Wray-Agarwal (WA) one-equation turbulence model for simulating multiphase flows, particularly focusing on cloud cavitation around a three-dimensional Clark-Y hydrofoil. Using unsteady Reynolds-Averaged Navier-Stokes (RANS) equations, numerical simulations with three different turbulence models—WA, <em>k-ω</em>, and Shear Stress Transport (SST) <em>k-ω</em>—are compared to experimental results. The comparison highlights key aspects such as hydrodynamic behavior, cavitation periodicity, and the interactions between cavitation and vortex structures. The WA model consistently demonstrates improved alignment with experimental data, showing smaller error margins than both <em>k-ω</em> and SST <em>k-ω</em> models, and effectively predicting the cyclical nature of cavitation. Analysis of vortex behavior through the Q-criterion and vorticity transport equation reveals that changes in vorticity are strongly influenced by the shape and dynamics of the cavity, with vortex stretching and volumetric expansion/contraction playing significant roles in the observed fluctuations. The interaction between the re-entrant jet and main flow is identified as the critical factor initiating sheet cavitation shedding, leading to the formation of cloud cavitation. These findings underscore the WA model’s effectiveness in accurately modeling cavitating flows and deepen the understanding of cavitation mechanisms.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"193 ","pages":"Article 105395"},"PeriodicalIF":3.8,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144828141","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}
Jiwei Shi , Yongxue Zhang , Lei Tian , Jianyong Yin , Jinya Zhang
{"title":"A numerical simulation study on the interaction between two horizontally placed cavitation bubbles near a rigid wall","authors":"Jiwei Shi , Yongxue Zhang , Lei Tian , Jianyong Yin , Jinya Zhang","doi":"10.1016/j.ijmultiphaseflow.2025.105393","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105393","url":null,"abstract":"<div><div>Investigating the evolution and interaction mechanism of double cavitation bubbles near rigid walls is fundamental to revealing the cavitation erosion mechanism of bubble groups on walls. Using a three-dimensional compressible two-phase flow model that accounts for vapor-liquid phase change mass transfer, this study numerically simulates the transient process and dynamic characteristics of equal-sized cavitation bubble pairs near a rigid wall. The results demonstrate strong agreement between simulated and experimental morphology of the bubble pairs near the rigid wall. The spacing of two bubbles and the distance of wall and bubbles are two key parameters that affect cavitation bubble characteristics. The bubble pair's collapse morphology at the minimum size moment varies with <em>γ</em> and <em>η</em> and follows a certain pattern. The angle between the liquid jet and the horizontal plane decreases as <em>γ</em> increases and increases as <em>η</em> increases.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"193 ","pages":"Article 105393"},"PeriodicalIF":3.8,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144780752","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}