Pub Date : 2025-11-12DOI: 10.1016/j.ijmultiphaseflow.2025.105538
Leandro Saraiva Valim , Luiz H. M. Lino , Adriana Teixeira , Adrieli Alcaires de Souza , Amadeu K. Sum , Rigoberto E. M. Morales , Moisés A. Marcelino Neto , Celina Kakitani , Laércio M. Junior , Annie Fidel-Dufour , Nicolas Lesage , Eric Serris , Jean-Michel Herri , Gianluca Lavalle , Ana Cameirão
A common challenge faced by oil and gas operators is the formation of gas hydrate blockages in production lines. There is no consensus on the methodologies and apparatus used to assess gas hydrate blockage risk, and extrapolating laboratory results to field conditions remains a significant challenge. This highlights the importance of comparing different techniques and experimental scales. This study aims to investigate the influence of key variables, such as shear, gas-liquid ratio, water cut, salinity, subcooling, gas composition, and wax content, on gas hydrate transportability at different scales. From an industrial perspective, the objective is to determine the most effective technique for translating laboratory data into field-scale applications. To this end, three experimental setups are employed: a high-pressure rheometer, a rock-flow cell, and a pilot-scale flow loop.
{"title":"Comparative assessment of gas hydrate transportability at different scales","authors":"Leandro Saraiva Valim , Luiz H. M. Lino , Adriana Teixeira , Adrieli Alcaires de Souza , Amadeu K. Sum , Rigoberto E. M. Morales , Moisés A. Marcelino Neto , Celina Kakitani , Laércio M. Junior , Annie Fidel-Dufour , Nicolas Lesage , Eric Serris , Jean-Michel Herri , Gianluca Lavalle , Ana Cameirão","doi":"10.1016/j.ijmultiphaseflow.2025.105538","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105538","url":null,"abstract":"<div><div>A common challenge faced by oil and gas operators is the formation of gas hydrate blockages in production lines. There is no consensus on the methodologies and apparatus used to assess gas hydrate blockage risk, and extrapolating laboratory results to field conditions remains a significant challenge. This highlights the importance of comparing different techniques and experimental scales. This study aims to investigate the influence of key variables, such as shear, gas-liquid ratio, water cut, salinity, subcooling, gas composition, and wax content, on gas hydrate transportability at different scales. From an industrial perspective, the objective is to determine the most effective technique for translating laboratory data into field-scale applications. To this end, three experimental setups are employed: a high-pressure rheometer, a rock-flow cell, and a pilot-scale flow loop.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"195 ","pages":"Article 105538"},"PeriodicalIF":3.8,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145569379","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}
Pub Date : 2025-11-11DOI: 10.1016/j.ijmultiphaseflow.2025.105527
Xiaohan Zheng , Zhijun Zhang , Guohua Tu , Chengwang Xiong , Muyang Wang , Shiping Wang
The aim of this study is to investigate the impact of Froude number, ventilation rate, and ventilation slit size on air-layer drag reduction (ALDR) in an axisymmetric underwater vehicle. Experiments were carried out in a recirculating water tunnel with a scaled-down SUBOFF submarine model, and the results were compared with numerical simulations performed using OpenFOAM. Five distinct air-layer morphologies are identified, distinguished by their symmetry and wake stability, which result in structures ranging from stable, symmetric layers to unstable, foam-like formations. The formation of these morphologies is governed by the interplay between buoyancy and inertia, with an increasing Froude number enhancing inertial forces over buoyancy to promote a transition from asymmetric to symmetric layers, while the ventilation rate primarily dictates the air layer coverage and the onset of instability. Moreover, larger slit sizes promote the formation of longer and thicker air layers, yet increased instability is observed at excessive ventilation rates. Optimal drag reduction occurs when low Froude numbers are paired with moderate ventilation rates, thereby facilitating the formation of a continuous and stable air layer. With further increases in ventilation rates, although wall shear stress is reduced over most of the surface, boundary layer separation is significantly enhanced, with a low-pressure region forming at the tail that considerably increases pressure drag. Consequently, the net drag reduction is weaker than expected at very high ventilation rates.
{"title":"On the effects of ventilation rate and Froude number on air-layer drag reduction over an axisymmetric underwater vehicle","authors":"Xiaohan Zheng , Zhijun Zhang , Guohua Tu , Chengwang Xiong , Muyang Wang , Shiping Wang","doi":"10.1016/j.ijmultiphaseflow.2025.105527","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105527","url":null,"abstract":"<div><div>The aim of this study is to investigate the impact of Froude number, ventilation rate, and ventilation slit size on air-layer drag reduction (ALDR) in an axisymmetric underwater vehicle. Experiments were carried out in a recirculating water tunnel with a scaled-down SUBOFF submarine model, and the results were compared with numerical simulations performed using OpenFOAM. Five distinct air-layer morphologies are identified, distinguished by their symmetry and wake stability, which result in structures ranging from stable, symmetric layers to unstable, foam-like formations. The formation of these morphologies is governed by the interplay between buoyancy and inertia, with an increasing Froude number enhancing inertial forces over buoyancy to promote a transition from asymmetric to symmetric layers, while the ventilation rate primarily dictates the air layer coverage and the onset of instability. Moreover, larger slit sizes promote the formation of longer and thicker air layers, yet increased instability is observed at excessive ventilation rates. Optimal drag reduction occurs when low Froude numbers are paired with moderate ventilation rates, thereby facilitating the formation of a continuous and stable air layer. With further increases in ventilation rates, although wall shear stress is reduced over most of the surface, boundary layer separation is significantly enhanced, with a low-pressure region forming at the tail that considerably increases pressure drag. Consequently, the net drag reduction is weaker than expected at very high ventilation rates.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"195 ","pages":"Article 105527"},"PeriodicalIF":3.8,"publicationDate":"2025-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145517913","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}
Pub Date : 2025-11-11DOI: 10.1016/j.ijmultiphaseflow.2025.105524
Jianhao Liu , Lianzhou Wang , Xinyu Liu
This study proposes a novel cavitation model that retains the second-order inertia term in the Rayleigh-Plesset (R-P) equation. This treatment captures the acceleration and deceleration phases of bubble growth and collapse, and establishes a fundamentally novel expression for the cavitation model. In place of traditional empirical constants, the model introduces physically interpretable parameters, including the critical nucleus radius and the molar density of non-condensable gas (NCG). Model performance was evaluated through simulations of cavitating flows around a NACA0015 hydrofoil and in a venturi tube using the open-source CFD (Computational Fluid Dynamics) platform OpenFOAM. The results were compared against those from the classical Schnerr–Sauer model and experimental data. For the hydrofoil case, the new model achieves improved agreement with experimental results in terms of lift/drag coefficients and surface pressure distribution. Notably, it reproduces more intense re-entrant jet structures and a more realistic bubble collapse process during unsteady cavitation shedding. In the venturi tube case, this model predicts the critical pressure ratio of the "cavitation-induced choked flow" phenomenon more accurately. Moreover, the dominant frequency of cavitation oscillation obtained when the pressure ratio is 0.5 is closer to the experimental value, and the reproduced bubble tail morphology is similar to the experimental observation. The proposed model accurately predicts cavitation behavior, demonstrating its significance for the advancement of numerical simulation tools for cavitation.
{"title":"Implementation and validation of a cavitation model with bubble inertia second-order term and non-condensable gas effects","authors":"Jianhao Liu , Lianzhou Wang , Xinyu Liu","doi":"10.1016/j.ijmultiphaseflow.2025.105524","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105524","url":null,"abstract":"<div><div>This study proposes a novel cavitation model that retains the second-order inertia term in the Rayleigh-Plesset (R-P) equation. This treatment captures the acceleration and deceleration phases of bubble growth and collapse, and establishes a fundamentally novel expression for the cavitation model. In place of traditional empirical constants, the model introduces physically interpretable parameters, including the critical nucleus radius and the molar density of non-condensable gas (NCG). Model performance was evaluated through simulations of cavitating flows around a NACA0015 hydrofoil and in a venturi tube using the open-source CFD (Computational Fluid Dynamics) platform OpenFOAM. The results were compared against those from the classical Schnerr–Sauer model and experimental data. For the hydrofoil case, the new model achieves improved agreement with experimental results in terms of lift/drag coefficients and surface pressure distribution. Notably, it reproduces more intense re-entrant jet structures and a more realistic bubble collapse process during unsteady cavitation shedding. In the venturi tube case, this model predicts the critical pressure ratio of the \"cavitation-induced choked flow\" phenomenon more accurately. Moreover, the dominant frequency of cavitation oscillation obtained when the pressure ratio is 0.5 is closer to the experimental value, and the reproduced bubble tail morphology is similar to the experimental observation. The proposed model accurately predicts cavitation behavior, demonstrating its significance for the advancement of numerical simulation tools for cavitation.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"195 ","pages":"Article 105524"},"PeriodicalIF":3.8,"publicationDate":"2025-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145569373","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}
Pub Date : 2025-11-11DOI: 10.1016/j.ijmultiphaseflow.2025.105531
Chang Liu , Fu-Ren Ming , Jing-Ping Xiao , Jia-Jie Wang , A-Man Zhang
The water entry of vehicles generates complex coupled dynamics involving cavity evolution and hydrodynamic forces, but the current understanding of these mechanisms requires further clarification. This paper develops an advanced water-entry experimental system featuring a novel optical image correction method and a high-impact-resistant measurement technique. Meanwhile, the Eulerian finite element method is applied for auxiliary analyses, and its accuracy and convergence are subsequently verified. Systematic investigations reveal that the wetting of the vehicle’s surface modulates force variations during water entry, while the pulsation of the cavity drives the internal pressure cyclical fluctuations. Notably, the Fr number and attitude angle critically govern cavity evolution and hydrodynamic force characteristics of the truncated cone vehicle. The peak coefficients of impact pressure, axial/normal force, and pitch torque are independent of the Fr numbers, and the cavity internal pressure decays linearly under varying Fr numbers. Moreover, the maximum axial and normal force coefficients exhibit approximate linear relationships with and ( is the attitude angle). Furthermore, the attenuation of internal cavity pressure becomes increasingly pronounced at larger attitude angles.
{"title":"Experimental study on coupling mechanism between cavity evolution and force characteristics during water entry of a truncated cone vehicle","authors":"Chang Liu , Fu-Ren Ming , Jing-Ping Xiao , Jia-Jie Wang , A-Man Zhang","doi":"10.1016/j.ijmultiphaseflow.2025.105531","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105531","url":null,"abstract":"<div><div>The water entry of vehicles generates complex coupled dynamics involving cavity evolution and hydrodynamic forces, but the current understanding of these mechanisms requires further clarification. This paper develops an advanced water-entry experimental system featuring a novel optical image correction method and a high-impact-resistant measurement technique. Meanwhile, the Eulerian finite element method is applied for auxiliary analyses, and its accuracy and convergence are subsequently verified. Systematic investigations reveal that the wetting of the vehicle’s surface modulates force variations during water entry, while the pulsation of the cavity drives the internal pressure cyclical fluctuations. Notably, the <em>Fr</em> number and attitude angle critically govern cavity evolution and hydrodynamic force characteristics of the truncated cone vehicle. The peak coefficients of impact pressure, axial/normal force, and pitch torque are independent of the <em>Fr</em> numbers, and the cavity internal pressure decays linearly under varying <em>Fr</em> numbers. Moreover, the maximum axial and normal force coefficients exhibit approximate linear relationships with <span><math><mrow><mo>tan</mo><msub><mrow><mi>θ</mi></mrow><mrow><mn>0</mn></mrow></msub></mrow></math></span> and <span><math><mrow><mo>cot</mo><msub><mrow><mi>θ</mi></mrow><mrow><mn>0</mn></mrow></msub></mrow></math></span> (<span><math><msub><mrow><mi>θ</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> is the attitude angle). Furthermore, the attenuation of internal cavity pressure becomes increasingly pronounced at larger attitude angles.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"195 ","pages":"Article 105531"},"PeriodicalIF":3.8,"publicationDate":"2025-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145517914","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}
Pub Date : 2025-11-10DOI: 10.1016/j.ijmultiphaseflow.2025.105534
Arindam Basak , Jai Prakash , G.P. Raja Sekhar
Surfactant impurities in multiphase emulsions can significantly modify the dynamics of small droplets by altering interfacial tension through adsorption–desorption kinetics. These interfacial variations are governed by the surface Péclet number, , which compares advective and diffusive transport of surfactants along the interface. While the effects of have been extensively studied in unbounded domains, their influence under confinement remains underexplored. In this work, we investigate the effects of small on the thermocapillary migration of a surfactant-laden spherical droplet near a planar wall, subjected to a uniform thermal gradient. Assuming negligible fluid inertia, we solve the axisymmetric Stokes equations inside and outside the droplet using a regular perturbation expansion in , formulated in bispherical coordinates via a streamfunction approach. A semi-analytical solution is developed to determine the droplet’s migration velocity and the associated flow fields. Our results reveal that surfactants begin to affect droplet motion at first order in , where thermocapillary stresses dominate the dynamics. For low viscosity ratios, the migration velocity increases rapidly with wall separation before saturating, while for higher viscosity ratios, saturation occurs at larger separations. We define a characteristic ‘screening length,’ the separation distance at which wall effects become negligible, which increases with both the viscosity ratio and the droplet-wall distance. Streamline analysis further reveals that, near the wall, flow is confined to a squeezed recirculation zone beneath the droplet, which transitions into broader recirculating structures as the droplet moves away. These findings provide new insights into the coupled effects of surfactant transport, confinement, and thermocapillarity, with potential applications in microfluidic and emulsion-based systems.
{"title":"Thermocapillary migration of a surfactant-laden droplet near a plane wall at low surface Péclet numbers","authors":"Arindam Basak , Jai Prakash , G.P. Raja Sekhar","doi":"10.1016/j.ijmultiphaseflow.2025.105534","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105534","url":null,"abstract":"<div><div>Surfactant impurities in multiphase emulsions can significantly modify the dynamics of small droplets by altering interfacial tension through adsorption–desorption kinetics. These interfacial variations are governed by the surface Péclet number, <span><math><mrow><mi>P</mi><msub><mrow><mi>e</mi></mrow><mrow><mi>s</mi></mrow></msub><mo>=</mo><msub><mrow><mtext>U</mtext></mrow><mrow><mi>c</mi></mrow></msub><mi>a</mi><mo>/</mo><msub><mrow><mi>D</mi></mrow><mrow><mi>s</mi></mrow></msub></mrow></math></span>, which compares advective and diffusive transport of surfactants along the interface. While the effects of <span><math><mrow><mi>P</mi><msub><mrow><mi>e</mi></mrow><mrow><mi>s</mi></mrow></msub></mrow></math></span> have been extensively studied in unbounded domains, their influence under confinement remains underexplored. In this work, we investigate the effects of small <span><math><mrow><mi>P</mi><msub><mrow><mi>e</mi></mrow><mrow><mi>s</mi></mrow></msub></mrow></math></span> on the thermocapillary migration of a surfactant-laden spherical droplet near a planar wall, subjected to a uniform thermal gradient. Assuming negligible fluid inertia, we solve the axisymmetric Stokes equations inside and outside the droplet using a regular perturbation expansion in <span><math><mrow><mi>P</mi><msub><mrow><mi>e</mi></mrow><mrow><mi>s</mi></mrow></msub></mrow></math></span>, formulated in bispherical coordinates via a streamfunction approach. A semi-analytical solution is developed to determine the droplet’s migration velocity and the associated flow fields. Our results reveal that surfactants begin to affect droplet motion at first order in <span><math><mrow><mi>P</mi><msub><mrow><mi>e</mi></mrow><mrow><mi>s</mi></mrow></msub></mrow></math></span>, where thermocapillary stresses dominate the dynamics. For low viscosity ratios, the migration velocity increases rapidly with wall separation before saturating, while for higher viscosity ratios, saturation occurs at larger separations. We define a characteristic ‘screening length,’ the separation distance at which wall effects become negligible, which increases with both the viscosity ratio and the droplet-wall distance. Streamline analysis further reveals that, near the wall, flow is confined to a squeezed recirculation zone beneath the droplet, which transitions into broader recirculating structures as the droplet moves away. These findings provide new insights into the coupled effects of surfactant transport, confinement, and thermocapillarity, with potential applications in microfluidic and emulsion-based systems.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"195 ","pages":"Article 105534"},"PeriodicalIF":3.8,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145517813","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}
Pub Date : 2025-11-10DOI: 10.1016/j.ijmultiphaseflow.2025.105532
Sagnik Nguyen-Paul, Ellen K. Longmire
In laminar pipe flow, neutrally buoyant particles accumulate at a certain radius near the wall depending on the pipe-to-particle diameter ratio () and pipe Reynolds number (). Transitional pipe flow containing intermittent puff structures and low particle volume fractions () was investigated to understand the interactive effects. For , puff spacing and transitional Reynolds number dropped substantially even at low (0.25%). By contrast, particles caused very little change in the transitional Reynolds number. Planar particle tracking velocimetry was performed to evaluate particle distribution and motion within puffs. Both particle sizes were found to accumulate at in laminar flow. Puffs disrupted this particle accumulation by transporting many of these particles inward to locations between and 0.9, somewhat flattening the radial distribution. Particle distributions took more than to recover to their initial values. Streamwise particle velocities matched closely with expected fluid velocities in the laminar part of the flow. Within the turbulent part of puffs, radial RMS fluid and particle velocities greatly exceeded values in fully developed turbulent flow. Longer particle trajectories evaluated in the turbulent part of the puff were unidirectional over time scales that corresponded closely with coherent vortical structures identified in single-phase flow. The disruption of particle accumulation near the wall was associated with wall-normal fluid ejections in single-phase transitional flow near the puff trailing edge.
在层流管道流动中，中性浮力颗粒根据管粒直径比（D/ D）和管雷诺数（Re）在管壁附近以一定半径聚集。研究了含有间歇泡芙结构和低颗粒体积分数（φ）的过渡管流，以了解相互作用的影响。当D/ D =44时，即使在低φ(0.25%)时，泡芙间距和过渡雷诺数也大幅下降。相比之下，D/ D =84颗粒对过渡雷诺数的影响很小。采用平面粒子跟踪测速法评价粒子在泡芙内的分布和运动。两种粒径在层流中均在0.93R处积聚。气泡通过向内输送许多粒子到r/ r =0.7和0.9之间的位置，破坏了这种粒子的积累，在某种程度上使径向分布变得平坦。颗粒分布需要90D以上才能恢复到初始值。沿流方向的粒子速度与流的层流部分的预期流体速度密切匹配。在泡芙的湍流部分，径向均数流体和颗粒速度大大超过了完全发展的湍流。在喷流湍流部分评估的较长的颗粒轨迹在时间尺度上是单向的，这与在单相流中确定的相干涡结构密切相关。在扑烟尾缘附近的单相过渡流动中，颗粒在壁面附近积聚的破坏与壁面正常的流体喷射有关。
{"title":"Experimental characterization of puff–particle interaction in transitional pipe flow","authors":"Sagnik Nguyen-Paul, Ellen K. Longmire","doi":"10.1016/j.ijmultiphaseflow.2025.105532","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105532","url":null,"abstract":"<div><div>In laminar pipe flow, neutrally buoyant particles accumulate at a certain radius near the wall depending on the pipe-to-particle diameter ratio (<span><math><mrow><mi>D</mi><mo>/</mo><mi>d</mi></mrow></math></span>) and pipe Reynolds number (<span><math><mrow><mi>R</mi><mi>e</mi></mrow></math></span>). Transitional pipe flow containing intermittent puff structures and low particle volume fractions (<span><math><mi>ϕ</mi></math></span>) was investigated to understand the interactive effects. For <span><math><mrow><mi>D</mi><mo>/</mo><mi>d</mi><mo>=</mo><mn>44</mn></mrow></math></span>, puff spacing and transitional Reynolds number dropped substantially even at low <span><math><mi>ϕ</mi></math></span> (0.25%). By contrast, <span><math><mrow><mi>D</mi><mo>/</mo><mi>d</mi><mo>=</mo><mn>84</mn></mrow></math></span> particles caused very little change in the transitional Reynolds number. Planar particle tracking velocimetry was performed to evaluate particle distribution and motion within puffs. Both particle sizes were found to accumulate at <span><math><mrow><mn>0</mn><mo>.</mo><mn>93</mn><mi>R</mi></mrow></math></span> in laminar flow. Puffs disrupted this particle accumulation by transporting many of these particles inward to locations between <span><math><mrow><mi>r</mi><mo>/</mo><mi>R</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>7</mn></mrow></math></span> and 0.9, somewhat flattening the radial distribution. Particle distributions took more than <span><math><mrow><mn>90</mn><mi>D</mi></mrow></math></span> to recover to their initial values. Streamwise particle velocities matched closely with expected fluid velocities in the laminar part of the flow. Within the turbulent part of puffs, radial RMS fluid and particle velocities greatly exceeded values in fully developed turbulent flow. Longer particle trajectories evaluated in the turbulent part of the puff were unidirectional over time scales that corresponded closely with coherent vortical structures identified in single-phase flow. The disruption of particle accumulation near the wall was associated with wall-normal fluid ejections in single-phase transitional flow near the puff trailing edge.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"195 ","pages":"Article 105532"},"PeriodicalIF":3.8,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145517909","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}
Pub Date : 2025-11-10DOI: 10.1016/j.ijmultiphaseflow.2025.105523
Nicolai Arent Quist , Simon Matlok , Stefan Sajin-Henningsen , Kar Mun Pang , Thomas Schaldemose Norman , Stefan Mayer , Jens Honoré Walther
A large-eddy simulation (LES) coupled with the volume-of-fluid (VOF) method and different cavitation growth models are employed to investigate the effect of physical properties of methanol and ammonia fuel on in-nozzle cavitation in a full-scale dual-hole fuel injector of a large marine two-stroke engine. The numerical approach is evaluated for hydraulic oil using particle image velocimetry (PIV) measurements and shadowgraph images from experiments with a transparent replica of the nozzle. The LES results show an accurate prediction of mass flow rates at different cavitation numbers with discrepancies less than 5% in the transition region between non-choked and choked flow conditions. The qualitative appearance of cavitation formation resembles the shadowgraph images at two different cavitation numbers. At the cavitation number of 1.3, a good agreement on transverse velocity profiles is seen between the LES results and PIV measurements, while at a higher cavitation number of 2.1, discrepancies are seen in regions where cavitation structures exist. Subsequently, the effects of non-isothermal physical properties of two alternative fuels, methanol and ammonia, are investigated and compared to -dodecane. A thermodynamic cooling effect is seen for methanol and ammonia due to a lower critical temperature and higher latent heat of vaporization. Two different cavitation growth rates, an inertia-controlled and a thermal-diffusion controlled, are evaluated for all three fuels and the results suggest that ammonia fuel is limited by thermal effects. Finally, a comparison of wall heat transfer for all three fuels shows that the heat transfer rates of methanol and ammonia are approximately two- and sevenfold compared to that of -dodecane, respectively, with the highest heat flux in the proximity of the cavitation region where liquid is attached to the wall.
{"title":"Numerical investigation on the effect of physical properties of alternative fuels on in-nozzle cavitation in a full-scale injector for a two-stroke marine engine","authors":"Nicolai Arent Quist , Simon Matlok , Stefan Sajin-Henningsen , Kar Mun Pang , Thomas Schaldemose Norman , Stefan Mayer , Jens Honoré Walther","doi":"10.1016/j.ijmultiphaseflow.2025.105523","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105523","url":null,"abstract":"<div><div>A large-eddy simulation (LES) coupled with the volume-of-fluid (VOF) method and different cavitation growth models are employed to investigate the effect of physical properties of methanol and ammonia fuel on in-nozzle cavitation in a full-scale dual-hole fuel injector of a large marine two-stroke engine. The numerical approach is evaluated for hydraulic oil using particle image velocimetry (PIV) measurements and shadowgraph images from experiments with a transparent replica of the nozzle. The LES results show an accurate prediction of mass flow rates at different cavitation numbers with discrepancies less than 5% in the transition region between non-choked and choked flow conditions. The qualitative appearance of cavitation formation resembles the shadowgraph images at two different cavitation numbers. At the cavitation number of 1.3, a good agreement on transverse velocity profiles is seen between the LES results and PIV measurements, while at a higher cavitation number of 2.1, discrepancies are seen in regions where cavitation structures exist. Subsequently, the effects of non-isothermal physical properties of two alternative fuels, methanol and ammonia, are investigated and compared to <span><math><mi>n</mi></math></span>-dodecane. A thermodynamic cooling effect is seen for methanol and ammonia due to a lower critical temperature and higher latent heat of vaporization. Two different cavitation growth rates, an inertia-controlled and a thermal-diffusion controlled, are evaluated for all three fuels and the results suggest that ammonia fuel is limited by thermal effects. Finally, a comparison of wall heat transfer for all three fuels shows that the heat transfer rates of methanol and ammonia are approximately two- and sevenfold compared to that of <span><math><mi>n</mi></math></span>-dodecane, respectively, with the highest heat flux in the proximity of the cavitation region where liquid is attached to the wall.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"195 ","pages":"Article 105523"},"PeriodicalIF":3.8,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145517911","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}
Pub Date : 2025-11-10DOI: 10.1016/j.ijmultiphaseflow.2025.105533
Di Zhao , Yang Li , Fuqiang Deng , Lingxin Zhang , Xinsheng Cheng
Cavitation-induced erosion in underwater structures is primarily attributed to the high pressures generated during the collapse of cavitation bubbles. To explore the mechanisms of these pressure impacts, this study presents a detailed three-dimensional numerical study on the collapse of bubble clusters near a solid wall and put forward a model for the pressure wave impact evaluation. Simulations are performed on the OpenFOAM platform utilizing a direct numerical simulation approach. The Volume of Fluid (VOF) method is employed to accurately capture the interface between the two phases. The results show that the collapse of bubble clusters near the wall displays an asynchronous layer-by-layer collapse pattern. The wall is subjected to several pressure wave impacts, with the most significant arising from the pressure wave released after the complete collapse of the bubble cluster. The jet also impacts the wall when the standoff distance is small enough. At high vapor volume fractions, parametric studies reveal that the pressure wave impact induced by 5-layer bubble clusters is independent of the radius of the internal bubbles , and increases exponentially with driving pressure . Within the range of , the pressure wave impact can be considered proportional to . And the pressure wave impact increases linearly with volume fraction when 0.238. We derived a theoretical formula for evaluating the amplitude of the pressure wave impact during bubble cluster collapse through the energy conversion mechanism. Moreover, The arrangements in dense spherical clusters have little effect on pressure wave impact at large stand-off distances, but become considerable when the cluster is very close to the wall, especially in sparse clusters. The geometric symmetry of bubble clusters may also exert a significant influence on the pressure wave impacts. This study can provide valuable insights for predicting cavitation damage for engineering applications.
{"title":"A model for evaluating the amplitude of pressure wave impacts generated by the collapse of bubble cluster near a solid wall","authors":"Di Zhao , Yang Li , Fuqiang Deng , Lingxin Zhang , Xinsheng Cheng","doi":"10.1016/j.ijmultiphaseflow.2025.105533","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105533","url":null,"abstract":"<div><div>Cavitation-induced erosion in underwater structures is primarily attributed to the high pressures generated during the collapse of cavitation bubbles. To explore the mechanisms of these pressure impacts, this study presents a detailed three-dimensional numerical study on the collapse of bubble clusters near a solid wall and put forward a model for the pressure wave impact evaluation. Simulations are performed on the OpenFOAM platform utilizing a direct numerical simulation approach. The Volume of Fluid (VOF) method is employed to accurately capture the interface between the two phases. The results show that the collapse of bubble clusters near the wall displays an asynchronous layer-by-layer collapse pattern. The wall is subjected to several pressure wave impacts, with the most significant arising from the pressure wave released after the complete collapse of the bubble cluster. The jet also impacts the wall when the standoff distance <span><math><msub><mrow><mi>γ</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span> is small enough. At high vapor volume fractions, parametric studies reveal that the pressure wave impact induced by 5-layer bubble clusters is independent of the radius of the internal bubbles <span><math><msub><mrow><mi>R</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span>, and increases exponentially with driving pressure <span><math><mrow><mi>Δ</mi><msup><mrow><mi>p</mi></mrow><mrow><mn>0</mn><mo>.</mo><mn>5</mn><mo>∼</mo><mn>0</mn><mo>.</mo><mn>6</mn></mrow></msup></mrow></math></span>. Within the range of <span><math><mrow><msub><mrow><mi>γ</mi></mrow><mrow><mi>c</mi></mrow></msub><mo>=</mo><mn>1</mn><mo>∼</mo><mn>3</mn></mrow></math></span>, the pressure wave impact can be considered proportional to <span><math><msubsup><mrow><mi>γ</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo>−</mo><mn>1</mn><mo>.</mo><mn>6</mn><mo>∼</mo><mo>−</mo><mn>1</mn><mo>.</mo><mn>5</mn></mrow></msubsup></math></span>. And the pressure wave impact increases linearly with volume fraction <span><math><msub><mrow><mi>α</mi></mrow><mrow><mi>v</mi></mrow></msub></math></span> when <span><math><mrow><msub><mrow><mi>α</mi></mrow><mrow><mi>v</mi></mrow></msub><mo>></mo></mrow></math></span>0.238. We derived a theoretical formula for evaluating the amplitude of the pressure wave impact during bubble cluster collapse through the energy conversion mechanism. Moreover, The arrangements in dense spherical clusters have little effect on pressure wave impact at large stand-off distances, but become considerable when the cluster is very close to the wall, especially in sparse clusters. The geometric symmetry of bubble clusters may also exert a significant influence on the pressure wave impacts. This study can provide valuable insights for predicting cavitation damage for engineering applications.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"195 ","pages":"Article 105533"},"PeriodicalIF":3.8,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145517912","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}
We investigate the dynamics of freely rising bubbles for a range of Eötvös and Morton numbers where a distinct skirt appears. This regime has not been studied in detail through experiments since the late 1970s. Using modern flow visualization techniques, such as high-speed photography and particle image velocimetry (PIV), we gain new insights by analyzing bubble shapes, terminal velocities, and drag forces, and compare our results with recent Direct Numerical Simulations (DNS) of skirt bubble behavior. Our findings confirm the existence of a maximum skirt length, beyond which the skirt becomes unstable. Notably, for the first time in experiments, we provide evidence of a secondary toroidal vortex inside the bubble skirt, observed in a moving frame of reference in agreement with the predictions from DNS.
{"title":"Experimental evidence of a double recirculation within the skirt of a skirt bubble","authors":"Mithun Ravisankar , Dongyue Wang , Omer Atasi , Dominique Legendre , Roberto Zenit","doi":"10.1016/j.ijmultiphaseflow.2025.105530","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105530","url":null,"abstract":"<div><div>We investigate the dynamics of freely rising bubbles for a range of Eötvös and Morton numbers where a distinct skirt appears. This regime has not been studied in detail through experiments since the late 1970s. Using modern flow visualization techniques, such as high-speed photography and particle image velocimetry (PIV), we gain new insights by analyzing bubble shapes, terminal velocities, and drag forces, and compare our results with recent Direct Numerical Simulations (DNS) of skirt bubble behavior. Our findings confirm the existence of a maximum skirt length, beyond which the skirt becomes unstable. Notably, for the first time in experiments, we provide evidence of a secondary toroidal vortex inside the bubble skirt, observed in a moving frame of reference in agreement with the predictions from DNS.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"195 ","pages":"Article 105530"},"PeriodicalIF":3.8,"publicationDate":"2025-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145517814","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}
A numerical investigation is conducted on the droplet dynamics and heat transfer associated with vapor condensation on the hybrid/mixed wettability surfaces featuring pillar structures, using an improved three-dimensional phase-change lattice Boltzmann model. This study primarily examines how various parameters of hydrophilic pillars with partial wettability manipulation affect droplet nucleation, growth and departure, as well as heat transfer capacity. The parameters explored include pillar height, base width, center-to-center spacing, and contact angles of both hydrophilic and hydrophobic regions. The results indicate that under fixed pillar dimensions and contact angles, a smaller center-to-center spacing increases the possibility of droplet coalescence through liquid bridge formation, which however hinders droplet removal and reduces heat transfer efficiency. Both excessively tall and overly short hydrophilic pillars decrease surface heat flux, while the former is due to increased droplet retention and inhibited detachment, and the latter is caused by insufficient hydrophilic area. Reducing the contact angle of either hydrophilic pillars or hydrophobic regions can improve overall heat transfer efficiency by increasing the heat flux. Furthermore, replacing the top walls of pillars from hydrophilic to hydrophobic facilitates the droplet departure, thereby improving the heat transfer performance. This numerical analysis contributes to a further understanding of vapor condensation behavior on hybrid wettability surfaces under phase-change conditions.
{"title":"Vapor condensation on pillar-structured surfaces with partial wettability manipulation","authors":"Tong Zheng, Xiangwei Yin, Tianle Yang, Shengqiang Shen, Gangtao Liang","doi":"10.1016/j.ijmultiphaseflow.2025.105528","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105528","url":null,"abstract":"<div><div>A numerical investigation is conducted on the droplet dynamics and heat transfer associated with vapor condensation on the hybrid/mixed wettability surfaces featuring pillar structures, using an improved three-dimensional phase-change lattice Boltzmann model. This study primarily examines how various parameters of hydrophilic pillars with partial wettability manipulation affect droplet nucleation, growth and departure, as well as heat transfer capacity. The parameters explored include pillar height, base width, center-to-center spacing, and contact angles of both hydrophilic and hydrophobic regions. The results indicate that under fixed pillar dimensions and contact angles, a smaller center-to-center spacing increases the possibility of droplet coalescence through liquid bridge formation, which however hinders droplet removal and reduces heat transfer efficiency. Both excessively tall and overly short hydrophilic pillars decrease surface heat flux, while the former is due to increased droplet retention and inhibited detachment, and the latter is caused by insufficient hydrophilic area. Reducing the contact angle of either hydrophilic pillars or hydrophobic regions can improve overall heat transfer efficiency by increasing the heat flux. Furthermore, replacing the top walls of pillars from hydrophilic to hydrophobic facilitates the droplet departure, thereby improving the heat transfer performance. This numerical analysis contributes to a further understanding of vapor condensation behavior on hybrid wettability surfaces under phase-change conditions.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"195 ","pages":"Article 105528"},"PeriodicalIF":3.8,"publicationDate":"2025-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145517907","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}
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