Pub Date : 2025-10-11DOI: 10.1016/j.ijmultiphaseflow.2025.105483
Ahmed Adila, Mohammad Ebadi, Wen Xi, Xiang Qi, Yu Jing, Peyman Mostaghimi, Ryan T. Armstrong
<div><div>Relative permeability (<span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span>) hysteresis reflects the complex interplay between capillary forces and fluid distributions in porous media, which affects multiphase flow predictions. Although traditional hysteresis models have been widely applied to oil–brine systems, gas–brine systems can exhibit reverse hysteresis behavior, and direct pore-scale comparisons between the two systems remain limited. This study compares <span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span> hysteresis of oil-brine and gas-brine systems using a simple glass-bead system that allows for precise pore-scale measures of fluid morphology during drainage and imbibition cycles. Our comparison confirms that gas-brine and oil-brine glass bead systems exhibit different hysteresis behaviors, with the gas-brine system showing a reversed trend where imbibition <span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span> is placed above drainage <span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span>. We find that the origin of the reverse trend results from changes in the behavior of the interfacial area (<span><math><msub><mrow><mi>A</mi></mrow><mrow><mi>n</mi><mi>w</mi></mrow></msub></math></span>) during drainage and imbibition, while all other morphological measures follow traditional hysteresis models. In general, we observe consistent trends between <span><math><msub><mrow><mi>A</mi></mrow><mrow><mi>n</mi><mi>w</mi></mrow></msub></math></span> and <span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span> hysteresis behaviors. Based on these findings, we present a <span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span> hysteresis model that reflects the observed trends and provides a framework for further investigation of the relative permeability in such systems. These findings contribute to a better understanding of multiphase flow in porous media, particularly in systems where gas transport is affected by hysteresis. The insights gained are especially relevant for cases exhibiting gas-brine hysteresis reversal behavior, offering a basis for further research into improving gas transport models in relevant applications.</div><div><strong>Plain Language Summary</strong></div><div>The flow of gas and water through porous materials is important for various applications, including subsurface energy storage. Here, we study how gas and brine flow through porous rocks using an analog glass bead system imaged with high-resolution X-ray, which provides 3-dimensional images of the fluids within the glass beads at a resolution that is one-tenth the diameter of human hair. Unlike typical models, we found that brine flows more easily after gas injection (imbibition) than during gas entry (drainage), which is the opposite of what is expected when water and oil
{"title":"Comparison of relative permeability hysteresis in oil-brine and gas-brine systems: A pore-scale investigation","authors":"Ahmed Adila, Mohammad Ebadi, Wen Xi, Xiang Qi, Yu Jing, Peyman Mostaghimi, Ryan T. Armstrong","doi":"10.1016/j.ijmultiphaseflow.2025.105483","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105483","url":null,"abstract":"<div><div>Relative permeability (<span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span>) hysteresis reflects the complex interplay between capillary forces and fluid distributions in porous media, which affects multiphase flow predictions. Although traditional hysteresis models have been widely applied to oil–brine systems, gas–brine systems can exhibit reverse hysteresis behavior, and direct pore-scale comparisons between the two systems remain limited. This study compares <span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span> hysteresis of oil-brine and gas-brine systems using a simple glass-bead system that allows for precise pore-scale measures of fluid morphology during drainage and imbibition cycles. Our comparison confirms that gas-brine and oil-brine glass bead systems exhibit different hysteresis behaviors, with the gas-brine system showing a reversed trend where imbibition <span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span> is placed above drainage <span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span>. We find that the origin of the reverse trend results from changes in the behavior of the interfacial area (<span><math><msub><mrow><mi>A</mi></mrow><mrow><mi>n</mi><mi>w</mi></mrow></msub></math></span>) during drainage and imbibition, while all other morphological measures follow traditional hysteresis models. In general, we observe consistent trends between <span><math><msub><mrow><mi>A</mi></mrow><mrow><mi>n</mi><mi>w</mi></mrow></msub></math></span> and <span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span> hysteresis behaviors. Based on these findings, we present a <span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span> hysteresis model that reflects the observed trends and provides a framework for further investigation of the relative permeability in such systems. These findings contribute to a better understanding of multiphase flow in porous media, particularly in systems where gas transport is affected by hysteresis. The insights gained are especially relevant for cases exhibiting gas-brine hysteresis reversal behavior, offering a basis for further research into improving gas transport models in relevant applications.</div><div><strong>Plain Language Summary</strong></div><div>The flow of gas and water through porous materials is important for various applications, including subsurface energy storage. Here, we study how gas and brine flow through porous rocks using an analog glass bead system imaged with high-resolution X-ray, which provides 3-dimensional images of the fluids within the glass beads at a resolution that is one-tenth the diameter of human hair. Unlike typical models, we found that brine flows more easily after gas injection (imbibition) than during gas entry (drainage), which is the opposite of what is expected when water and oil","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"194 ","pages":"Article 105483"},"PeriodicalIF":3.8,"publicationDate":"2025-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145320509","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 : 2025-10-10DOI: 10.1016/j.ijmultiphaseflow.2025.105482
Jiaxing Ren , Fangdong Wang , Shiwei Guo , Weiqiang Xu , Masroor Ahmad , Ruifeng Tian , Puzhen Gao , Shouxu Qiao , Sichao Tan
A thorough understanding of the flow structures and characteristics of bubbly-to-cap bubbly transition flow is crucial for developing constitutive correlations for flow regime transition. In the present study, a four-sensor conductivity probe is used to measure the local distribution of interfacial parameters, including void fraction, interfacial area concentration, Sauter mean diameter, and bubble velocity across the entire cross-sectional area in a vertical upward 5 × 5 rod bundle. High-speed photography is also employed to obtain the visualization of the flow structure by introducing the fluorinated ethylene propylene (FEP) rod to match the index of refraction. The test matrix includes 18 flow conditions near the transition regions from bubbly to cap bubbly flows. A distinct wing-shaped deformation of cap bubbles and the acceleration of spherical bubbles in wake regions are observed through the flow visualization. The enhanced wake entrainment effect in subchannels should be considered in the modeling of flow regime transition criteria. As the void fraction increases, cap bubbles spanning 2–3 subchannels concentrate toward the channel box center. Cap bubbles initially form in the interior subchannels near the channel center, while the edge and corner subchannels retain bubbly flow. The non-uniform void distribution reduces the global area-averaged void fraction, promoting the earlier formation of cap bubbles before reaching the critical value. Moreover, the experimental database is used to verify the existing drift-flux correlations. It is found that the cap bubbly flow has a larger drift velocity than that for bubbly flow because of the greater buoyancy force acting on Group 2 bubbles and the additional acceleration caused by wake entrainment effects on Group 1 bubbles. Most recently developed drift-flux correlations considering the difference of drift velocity for two flow regimes can reasonably predict the one-dimensional void fraction with an accuracy of approximately ±15 %. The two-group drift-flux model also shows great performance in predicting gas velocity for bubbly-to-cap bubbly transition flows, with an accuracy for Group 1 and Group 2 bubbles of 6.75 % and 19.99 %, respectively.
{"title":"Experimental study on characteristics of interfacial structure from bubbly to cap bubbly flow in a 5 × 5 rod bundle","authors":"Jiaxing Ren , Fangdong Wang , Shiwei Guo , Weiqiang Xu , Masroor Ahmad , Ruifeng Tian , Puzhen Gao , Shouxu Qiao , Sichao Tan","doi":"10.1016/j.ijmultiphaseflow.2025.105482","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105482","url":null,"abstract":"<div><div>A thorough understanding of the flow structures and characteristics of bubbly-to-cap bubbly transition flow is crucial for developing constitutive correlations for flow regime transition. In the present study, a four-sensor conductivity probe is used to measure the local distribution of interfacial parameters, including void fraction, interfacial area concentration, Sauter mean diameter, and bubble velocity across the entire cross-sectional area in a vertical upward 5 × 5 rod bundle. High-speed photography is also employed to obtain the visualization of the flow structure by introducing the fluorinated ethylene propylene (FEP) rod to match the index of refraction. The test matrix includes 18 flow conditions near the transition regions from bubbly to cap bubbly flows. A distinct wing-shaped deformation of cap bubbles and the acceleration of spherical bubbles in wake regions are observed through the flow visualization. The enhanced wake entrainment effect in subchannels should be considered in the modeling of flow regime transition criteria. As the void fraction increases, cap bubbles spanning 2–3 subchannels concentrate toward the channel box center. Cap bubbles initially form in the interior subchannels near the channel center, while the edge and corner subchannels retain bubbly flow. The non-uniform void distribution reduces the global area-averaged void fraction, promoting the earlier formation of cap bubbles before reaching the critical value. Moreover, the experimental database is used to verify the existing drift-flux correlations. It is found that the cap bubbly flow has a larger drift velocity than that for bubbly flow because of the greater buoyancy force acting on Group 2 bubbles and the additional acceleration caused by wake entrainment effects on Group 1 bubbles. Most recently developed drift-flux correlations considering the difference of drift velocity for two flow regimes can reasonably predict the one-dimensional void fraction with an accuracy of approximately ±15 %. The two-group drift-flux model also shows great performance in predicting gas velocity for bubbly-to-cap bubbly transition flows, with an accuracy for Group 1 and Group 2 bubbles of 6.75 % and 19.99 %, respectively.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"194 ","pages":"Article 105482"},"PeriodicalIF":3.8,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145358134","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 : 2025-10-10DOI: 10.1016/j.ijmultiphaseflow.2025.105484
Gerald Gallagher , Fergal J. Boyle
The accurate simulation of blood, which is a multiphase biofluid comprised of plasma and cellular components, is important for biomedical applications. Computational fluid dynamics is routinely used for blood simulation but traditionally treats the flow field as homogeneous. Red blood cell dynamics and deformation are important as they occupy approximately 45% of the volume in blood and control viscosity and non-Newtonian behaviour. Healthy and diseased red blood cells differ in shape and properties, and an understanding of the behaviour of these cells in flow allows for better insight into in-vitro and in-vivo applications such as early-stage disease identification, non-chemical cell separation, and blood viscosity reduction. A developed lattice Boltzmann-immersed boundary solver with a spring-particle cell model was used to analyse discocyte and echinocyte-II red blood cells moving due to shear flow, settling due to gravitational forces, and moving and deforming due to larger magnetic forces. Echinocyte-II cells were the focus of this work due to their association with early-stage disease. Predicted deformation in shear flow and terminal velocities due to gravitational forces for the discocytes compared well with experimental measurements. The larger deformability of the discocyte cells compared with the echinocyte-II cells for the magnetic force case resulted in larger changes to velocities in the early stages of the simulation due to transient deformability-driven drag modulation, indicating intermittent forces may be useful for non-chemical cell separation. The solver can be considered robust for modelling moving red blood cells and applied body forces can be tuned for accurate cell manipulation applications.
{"title":"Body force influence on healthy and diseased red blood cell sedimentation using multiphase CFD methods","authors":"Gerald Gallagher , Fergal J. Boyle","doi":"10.1016/j.ijmultiphaseflow.2025.105484","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105484","url":null,"abstract":"<div><div>The accurate simulation of blood, which is a multiphase biofluid comprised of plasma and cellular components, is important for biomedical applications. Computational fluid dynamics is routinely used for blood simulation but traditionally treats the flow field as homogeneous. Red blood cell dynamics and deformation are important as they occupy approximately 45% of the volume in blood and control viscosity and non-Newtonian behaviour. Healthy and diseased red blood cells differ in shape and properties, and an understanding of the behaviour of these cells in flow allows for better insight into <em>in-vitro</em> and <em>in-vivo</em> applications such as early-stage disease identification, non-chemical cell separation, and blood viscosity reduction. A developed lattice Boltzmann-immersed boundary solver with a spring-particle cell model was used to analyse discocyte and echinocyte-II red blood cells moving due to shear flow, settling due to gravitational forces, and moving and deforming due to larger magnetic forces. Echinocyte-II cells were the focus of this work due to their association with early-stage disease. Predicted deformation in shear flow and terminal velocities due to gravitational forces for the discocytes compared well with experimental measurements. The larger deformability of the discocyte cells compared with the echinocyte-II cells for the magnetic force case resulted in larger changes to velocities in the early stages of the simulation due to transient deformability-driven drag modulation, indicating intermittent forces may be useful for non-chemical cell separation. The solver can be considered robust for modelling moving red blood cells and applied body forces can be tuned for accurate cell manipulation applications.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"195 ","pages":"Article 105484"},"PeriodicalIF":3.8,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145464013","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 : 2025-10-10DOI: 10.1016/j.ijmultiphaseflow.2025.105478
Sotirios Damianos , Andreas Papoutsakis , Ioannis K. Karathanassis , Manolis Gavaises
The presence of entrapped gas in liquids is well-documented, arising from gas solubility, surface irregularities, or prior phase-change events. In this study, simulations are carried out replicating an experiment involving a Mach 2.4 Planar shock interacting with a cylindrical water column, and the results are benchmarked against experimental pressure measurements in which the presence of entrapped air is reported. The liquid droplet is modelled as a homogeneous mixture of liquid and gas using a multiphase flow framework, and a novel relaxation approach is introduced to capture non-equilibrium effects within the mixture region. The effects of Gaseous Volume Fraction (GVF) and relaxation rate on shock attenuation, wave propagation speed, and cavitation are explored. The results reveal that increasing GVF enhances shock attenuation and slows down the wave propagation speed due to the mixture’s higher compressibility. A non-monotonic relationship between relaxation rate and pressure peak intensity is observed, governed by the effect of the relaxation rate on shock diffusivity, with maximum attenuation occurring at intermediate rates. At high GVF, the low wave propagation speed leads to an interaction between the shocks formed internally and around the droplet, which suppresses the rarefaction wave formation. Regarding cavitation, results indicate that lower GVF promotes stronger gas growth due to less shock attenuation. Finally, this study provides a physical explanation for the temporal pressure variations reported in prior numerical works and highlights the critical role of entrapped gas in shock–droplet interaction dynamics.
{"title":"Effect of gas nuclei on the primary stage of shock–droplet interaction","authors":"Sotirios Damianos , Andreas Papoutsakis , Ioannis K. Karathanassis , Manolis Gavaises","doi":"10.1016/j.ijmultiphaseflow.2025.105478","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105478","url":null,"abstract":"<div><div>The presence of entrapped gas in liquids is well-documented, arising from gas solubility, surface irregularities, or prior phase-change events. In this study, simulations are carried out replicating an experiment involving a Mach 2.4 Planar shock interacting with a cylindrical water column, and the results are benchmarked against experimental pressure measurements in which the presence of entrapped air is reported. The liquid droplet is modelled as a homogeneous mixture of liquid and gas using a multiphase flow framework, and a novel relaxation approach is introduced to capture non-equilibrium effects within the mixture region. The effects of Gaseous Volume Fraction (GVF) and relaxation rate on shock attenuation, wave propagation speed, and cavitation are explored. The results reveal that increasing GVF enhances shock attenuation and slows down the wave propagation speed due to the mixture’s higher compressibility. A non-monotonic relationship between relaxation rate and pressure peak intensity is observed, governed by the effect of the relaxation rate on shock diffusivity, with maximum attenuation occurring at intermediate rates. At high GVF, the low wave propagation speed leads to an interaction between the shocks formed internally and around the droplet, which suppresses the rarefaction wave formation. Regarding cavitation, results indicate that lower GVF promotes stronger gas growth due to less shock attenuation. Finally, this study provides a physical explanation for the temporal pressure variations reported in prior numerical works and highlights the critical role of entrapped gas in shock–droplet interaction dynamics.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"194 ","pages":"Article 105478"},"PeriodicalIF":3.8,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145262802","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 : 2025-10-09DOI: 10.1016/j.ijmultiphaseflow.2025.105481
Razqan Razak, Paula A Gago, Zhixi Chen, Stephen Tyson, Sheikh S Rahman
Premium-type standalone sand screens are increasingly used in oil and gas well completions for their cost-effectiveness and operational simplicity. Their filtration performance involves two coupled phases: initial bridging of sand particles at the screen surface and the subsequent deposited filter-bed formation, which governs long-term retention and flow. The influence of screen geometry on this progression remains under-characterised, with past studies often separating these phases or applying inconsistent methods.
This study evaluates how weave pattern and layering shape the transition from bridging to filter-bed control using a spatially resolved CFD-DEM framework. Four configurations were analysed: plain weave (PW), twill weave (TW), and their multilayer forms (ML-PW, ML-TW). Parameters such as aperture size, wire diameter, and interlayer registration were held constant to isolate geometric effects.
Multilayer screens outperformed single layers, with ML-PW showing the lowest sand production, smoothest decline in production rate, and most stable filtrate size range. PW achieved the highest retained permeability (%), but this reflected its lower inherent screen-only permeability rather than the stability of flow coherence. ML-PW demonstrated the strongest overall performance by combining high retention with coherent flow paths and stable bridging, whereas TW and ML-TW showed weaker alignment, greater heterogeneity, and lower retained permeability.
The findings establish layering as a stronger driver of filtration behaviour than weave alone. PW performs better than TW at equivalent aperture, while ML-PW provides the most balanced combination of fines control and hydraulic capacity. Filtration should therefore be assessed as a time-dependent progression governed jointly by screen geometry and filter-bed development.
{"title":"Influence of weave geometry and layering on the progression of sand retention and permeability in standalone screens using resolved CFD-DEM","authors":"Razqan Razak, Paula A Gago, Zhixi Chen, Stephen Tyson, Sheikh S Rahman","doi":"10.1016/j.ijmultiphaseflow.2025.105481","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105481","url":null,"abstract":"<div><div>Premium-type standalone sand screens are increasingly used in oil and gas well completions for their cost-effectiveness and operational simplicity. Their filtration performance involves two coupled phases: initial bridging of sand particles at the screen surface and the subsequent deposited filter-bed formation, which governs long-term retention and flow. The influence of screen geometry on this progression remains under-characterised, with past studies often separating these phases or applying inconsistent methods.</div><div>This study evaluates how weave pattern and layering shape the transition from bridging to filter-bed control using a spatially resolved CFD-DEM framework. Four configurations were analysed: plain weave (PW), twill weave (TW), and their multilayer forms (ML-PW, ML-TW). Parameters such as aperture size, wire diameter, and interlayer registration were held constant to isolate geometric effects.</div><div>Multilayer screens outperformed single layers, with ML-PW showing the lowest sand production, smoothest decline in production rate, and most stable filtrate size range. PW achieved the highest retained permeability (%), but this reflected its lower inherent screen-only permeability rather than the stability of flow coherence. ML-PW demonstrated the strongest overall performance by combining high retention with coherent flow paths and stable bridging, whereas TW and ML-TW showed weaker alignment, greater heterogeneity, and lower retained permeability.</div><div>The findings establish layering as a stronger driver of filtration behaviour than weave alone. PW performs better than TW at equivalent aperture, while ML-PW provides the most balanced combination of fines control and hydraulic capacity. Filtration should therefore be assessed as a time-dependent progression governed jointly by screen geometry and filter-bed development.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"194 ","pages":"Article 105481"},"PeriodicalIF":3.8,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145320967","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 : 2025-10-09DOI: 10.1016/j.ijmultiphaseflow.2025.105473
Jia-Jie Wang , Chang Liu , Xiao-Qiang Chen , Fu-Ren Ming , A-Man Zhang
Crossing the air–water interface during water entry subjects vehicles to severe impact forces, posing significant risks such as structural vibration, large deformation, and motion instability. To mitigate these effects, this study proposes a tandem water entry strategy utilizing a perforated leading vehicle to reduce impact forces. The main vehicle vertically penetrates the cavity wall formed by the leading vehicle, thereby attenuating impact forces. The water entry process is simulated using the delta-smoothed particle hydrodynamics (-SPH) method, whose convergence and accuracy are verified against experimental results. Analysis of main cavity evolution, pressure distribution, and water-jet impacts elucidates the force reduction mechanism of the tandem strategy. Furthermore, the influences of the leading vehicle’s initial velocity and attitude angle on the main vehicle’s impact forces are investigated. Results demonstrate a reduction in peak axial force of up to 90% while ensuring collision avoidance. Increasing the relative attitude angle between vehicles and the initial velocity ratio further minimizes collision risk. These findings offer valuable insights for developing efficient and operationally feasible impact force reduction techniques.
{"title":"Research on leading-vehicle-based force reduction for main vehicle in vertical water entry","authors":"Jia-Jie Wang , Chang Liu , Xiao-Qiang Chen , Fu-Ren Ming , A-Man Zhang","doi":"10.1016/j.ijmultiphaseflow.2025.105473","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105473","url":null,"abstract":"<div><div>Crossing the air–water interface during water entry subjects vehicles to severe impact forces, posing significant risks such as structural vibration, large deformation, and motion instability. To mitigate these effects, this study proposes a tandem water entry strategy utilizing a perforated leading vehicle to reduce impact forces. The main vehicle vertically penetrates the cavity wall formed by the leading vehicle, thereby attenuating impact forces. The water entry process is simulated using the delta-smoothed particle hydrodynamics (<span><math><mi>δ</mi></math></span>-SPH) method, whose convergence and accuracy are verified against experimental results. Analysis of main cavity evolution, pressure distribution, and water-jet impacts elucidates the force reduction mechanism of the tandem strategy. Furthermore, the influences of the leading vehicle’s initial velocity and attitude angle on the main vehicle’s impact forces are investigated. Results demonstrate a reduction in peak axial force of up to 90% while ensuring collision avoidance. Increasing the relative attitude angle between vehicles and the initial velocity ratio further minimizes collision risk. These findings offer valuable insights for developing efficient and operationally feasible impact force reduction techniques.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"194 ","pages":"Article 105473"},"PeriodicalIF":3.8,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145262799","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 : 2025-10-08DOI: 10.1016/j.ijmultiphaseflow.2025.105479
July A. Gómez-Camperos , Carlos M. R․ Diaz , Marlon M. Hernandez-Cely , Oscar M. H․ Rodriguez , Aldo Pardo-Garcia
Accurate identification of dense-gas/liquid two-phase flow patterns is essential in pipeline fluid transport systems and oil well operations. However, conventional methods for classifying these patterns rely mostly on direct visual observation and sensors installed in the system. This study presents an innovative approach for flow pattern recognition, based on modified convolutional neural network (CNN) algorithms and transfer learning based on regularization techniques to achieve an automatic and objective identification of patterns in dense-gas/liquid flows. Experiments were carried out in the Multiphase Flow Experimental Platform of the Industrial Multiphase Flow Laboratory (LEMI). Six flow patterns in horizontal pipes were identified, generating a database of 67,710 images, which are divided into three categories: 60 % are used for model training, 20 % for validation and the remaining 20 % for model evaluation. The proposed model was evaluated on eighteen modified convolutional neural network architectures, and in six test sets. The computational results showed that the proposed model was able to identify the two-phase flow patterns correctly with an accuracy of 1.0 with MobileNet, InceptionV3, InceptionResNetV2 architectures, in the fourth test set, standing out in performance among the six evaluated sets without presenting over-fitting signals. In contrast, the ResNet50, ResNet152V2, MobileNetV3Small, MobileNetV3Large, ResNet101V2, InceptionV4, AlexNet and Linet5 models failed to achieve an accuracy higher than 0.2, obtaining the lowest results in the training sets.
{"title":"Dense-gas/liquid two-phase flow pattern recognition using convolutional neural networks and transfer learning","authors":"July A. Gómez-Camperos , Carlos M. R․ Diaz , Marlon M. Hernandez-Cely , Oscar M. H․ Rodriguez , Aldo Pardo-Garcia","doi":"10.1016/j.ijmultiphaseflow.2025.105479","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105479","url":null,"abstract":"<div><div>Accurate identification of dense-gas/liquid two-phase flow patterns is essential in pipeline fluid transport systems and oil well operations. However, conventional methods for classifying these patterns rely mostly on direct visual observation and sensors installed in the system. This study presents an innovative approach for flow pattern recognition, based on modified convolutional neural network (CNN) algorithms and transfer learning based on regularization techniques to achieve an automatic and objective identification of patterns in dense-gas/liquid flows. Experiments were carried out in the Multiphase Flow Experimental Platform of the Industrial Multiphase Flow Laboratory (LEMI). Six flow patterns in horizontal pipes were identified, generating a database of 67,710 images, which are divided into three categories: 60 % are used for model training, 20 % for validation and the remaining 20 % for model evaluation. The proposed model was evaluated on eighteen modified convolutional neural network architectures, and in six test sets. The computational results showed that the proposed model was able to identify the two-phase flow patterns correctly with an accuracy of 1.0 with MobileNet, InceptionV3, InceptionResNetV2 architectures, in the fourth test set, standing out in performance among the six evaluated sets without presenting over-fitting signals. In contrast, the ResNet50, ResNet152V2, MobileNetV3Small, MobileNetV3Large, ResNet101V2, InceptionV4, AlexNet and Linet5 models failed to achieve an accuracy higher than 0.2, obtaining the lowest results in the training sets.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"194 ","pages":"Article 105479"},"PeriodicalIF":3.8,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145320510","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 : 2025-10-08DOI: 10.1016/j.ijmultiphaseflow.2025.105477
Carlos Mauricio Ruiz-Diaz , Cristhian E.A. Pacheco , Edson Orati da Silva , Gustavo Bochio , Alberto T. Postal , Oscar M.H. Rodriguez
High pressures, critical temperatures, and elevated CO₂ concentrations in ultradeep offshore reservoirs lead to the formation of dense gases within production systems. These conditions result in two-phase flow with dense gas, a flow condition still poorly understood, particularly under slight inclinations. This study presents an extensive experimental investigation of such flow using sulfur hexafluoride (SF₆) and mineral oil in a 2-inch pipeline. A total of 158 data points were obtained under controlled conditions for inclinations of 0°, 5°, and 10°. Holdup was measured using gamma-ray densitometry, and frictional pressure gradients data were evaluated along with flow pattern characterization. The test matrix covered superficial liquid velocities from 0.02 to 2.0 m/s and gas velocities from 0.05 to 1.5 m/s with the liquid-gas density ratio below 10. Transitional flow patterns, i.e., pseudo-slug and dual-continuous, were observed, being the latter atypical in gas-liquid flow. Stratified flow patterns disappeared entirely at inclinations of 5° and 10°, while dispersed flows expanded likely due to inclination-induced phase redistribution. Comparisons with leading commercial simulators highlighted notable discrepancies in holdup and pressure gradient predictions, especially under transitional and stratified flow conditions. These findings underline the need for inclination-aware modeling strategies and offer a valuable experimental database to improve simulator performance in dense-gas/liquid multiphase flows.
{"title":"Experimental study on dense-gas/oil flow in horizontal and slightly upward inclined pipes","authors":"Carlos Mauricio Ruiz-Diaz , Cristhian E.A. Pacheco , Edson Orati da Silva , Gustavo Bochio , Alberto T. Postal , Oscar M.H. Rodriguez","doi":"10.1016/j.ijmultiphaseflow.2025.105477","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105477","url":null,"abstract":"<div><div>High pressures, critical temperatures, and elevated CO₂ concentrations in ultradeep offshore reservoirs lead to the formation of dense gases within production systems. These conditions result in two-phase flow with dense gas, a flow condition still poorly understood, particularly under slight inclinations. This study presents an extensive experimental investigation of such flow using sulfur hexafluoride (SF₆) and mineral oil in a 2-inch pipeline. A total of 158 data points were obtained under controlled conditions for inclinations of 0°, 5°, and 10°. Holdup was measured using gamma-ray densitometry, and frictional pressure gradients data were evaluated along with flow pattern characterization. The test matrix covered superficial liquid velocities from 0.02 to 2.0 m/s and gas velocities from 0.05 to 1.5 m/s with the liquid-gas density ratio below 10. Transitional flow patterns, i.e., pseudo-slug and dual-continuous, were observed, being the latter atypical in gas-liquid flow. Stratified flow patterns disappeared entirely at inclinations of 5° and 10°, while dispersed flows expanded likely due to inclination-induced phase redistribution. Comparisons with leading commercial simulators highlighted notable discrepancies in holdup and pressure gradient predictions, especially under transitional and stratified flow conditions. These findings underline the need for inclination-aware modeling strategies and offer a valuable experimental database to improve simulator performance in dense-gas/liquid multiphase flows.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"194 ","pages":"Article 105477"},"PeriodicalIF":3.8,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145320508","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 : 2025-10-08DOI: 10.1016/j.ijmultiphaseflow.2025.105475
Halvard Thon, Galina Simonsen, Paul Roger Leinan
In this work drop dispersion of disintegrating jets for a liquid–liquid system in a direct contact thermal energy storage pilot was investigated experimentally. The coalescence behavior of the dense packed emulsion layer was linked to the size of drops. It was found that coalescence rates were strongly affected by the drop sizes, where a three-fold increase was achieved by increasing the drop sizes. By varying the number and size of injection nozzles, drop sizes from 1 to mm were produced. Drop size distributions were studied and described in terms of the inlet jet breakup behavior, which was quantified by the Ohnesorge and Reynolds numbers.
{"title":"Drop dispersion and coalescence in a direct contact thermal energy storage","authors":"Halvard Thon, Galina Simonsen, Paul Roger Leinan","doi":"10.1016/j.ijmultiphaseflow.2025.105475","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105475","url":null,"abstract":"<div><div>In this work drop dispersion of disintegrating jets for a liquid–liquid system in a direct contact thermal energy storage pilot was investigated experimentally. The coalescence behavior of the dense packed emulsion layer was linked to the size of drops. It was found that coalescence rates were strongly affected by the drop sizes, where a three-fold increase was achieved by increasing the drop sizes. By varying the number and size of injection nozzles, drop sizes from <span><math><mo><</mo></math></span>1 to <span><math><mrow><mo>></mo><mn>10</mn></mrow></math></span> mm were produced. Drop size distributions were studied and described in terms of the inlet jet breakup behavior, which was quantified by the Ohnesorge and Reynolds numbers.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"194 ","pages":"Article 105475"},"PeriodicalIF":3.8,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145262804","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 : 2025-10-08DOI: 10.1016/j.ijmultiphaseflow.2025.105480
Zhifan Zhang , Yan Shao , Qi Zhang , Yujie Xie , Yutong Sui , Guiyong Zhang
The instability problem of vehicles entering water obliquely across media has attracted considerable attention. This study proposes the use of preset bubbles to improve water-entry stability and investigates the influence of length-to-diameter ratio on the stabilization effect. By conducting oblique water-entry experiments of the vehicle and establishing an FVM numerical model based on the experiments, the simulation and experimental displacement curves show good agreement. The research found that the stability of the vehicle is jointly influenced by the whipping moment, free-surface splashing, external moments from cavity closure, and tail-flapping moments. Under certain conditions, cavity-induced water jets can also affect the vehicle's motion stability. While the preset bubble can reduce the peak pitching moment, it shortens the closure time of the tail cavity, which may enhance the influence of external moments; therefore, the stabilization effect has its limitations. The comparison shows that the preset bubble significantly improves the stability of the vehicles with length-to-diameter ratios of 4 and 8, while no noticeable improvement is observed at length-to-diameter ratios of 14 and 24. Additionally, the closure time of the tail cavity is inversely proportional to the length-to-diameter ratio, and the bubble-induced acceleration of cavity closure weakens as the length-to-diameter ratio increases. This research provides fundamental technical support for the design of load reduction and stability enhancement for high-speed water-entry vehicles.
{"title":"Mechanism study on the effect of pre-set bubbles near the free surface on the water-entry trajectory stability of vehicles with different length-to-diameter ratios","authors":"Zhifan Zhang , Yan Shao , Qi Zhang , Yujie Xie , Yutong Sui , Guiyong Zhang","doi":"10.1016/j.ijmultiphaseflow.2025.105480","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105480","url":null,"abstract":"<div><div>The instability problem of vehicles entering water obliquely across media has attracted considerable attention. This study proposes the use of preset bubbles to improve water-entry stability and investigates the influence of length-to-diameter ratio on the stabilization effect. By conducting oblique water-entry experiments of the vehicle and establishing an FVM numerical model based on the experiments, the simulation and experimental displacement curves show good agreement. The research found that the stability of the vehicle is jointly influenced by the whipping moment, free-surface splashing, external moments from cavity closure, and tail-flapping moments. Under certain conditions, cavity-induced water jets can also affect the vehicle's motion stability. While the preset bubble can reduce the peak pitching moment, it shortens the closure time of the tail cavity, which may enhance the influence of external moments; therefore, the stabilization effect has its limitations. The comparison shows that the preset bubble significantly improves the stability of the vehicles with length-to-diameter ratios of 4 and 8, while no noticeable improvement is observed at length-to-diameter ratios of 14 and 24. Additionally, the closure time of the tail cavity is inversely proportional to the length-to-diameter ratio, and the bubble-induced acceleration of cavity closure weakens as the length-to-diameter ratio increases. This research provides fundamental technical support for the design of load reduction and stability enhancement for high-speed water-entry vehicles.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"194 ","pages":"Article 105480"},"PeriodicalIF":3.8,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145320969","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：