Pub Date : 2025-11-04DOI: 10.1016/j.ijmultiphaseflow.2025.105510
Haokun Zhang , Thomas Höhne
Efficient oil-water separation is increasingly vital in mature oilfields, where enhanced water production challenges conventional downhole separation technologies. The vane-type pipe separator (VTPS) offers a promising solution due to its compact configuration and superior phase separation efficiency in constrained environments. However, the inherent complexities of swirling multiphase flow necessitate advanced modeling approaches for performance optimization. In this study, a comprehensive computational framework based on the Algebraic Interfacial Area Density (AIAD) model within an Euler-Euler multiphase context is developed and validated against benchmarked experimental data. Sensitivity analysis employing response surface methodology (RSM) and global-local indices quantifies the influence of key decision parameters, including guide vane installation angle, inlet flow rate, oil fraction, and split ratio, on separator performance. The study elucidates the parametric interplay affecting pressure drop and oil recovery, revealing guide vane angle and oil fraction as the dominant factors for hydraulic and separation performance, respectively. A multi-objective optimization is conducted using the Strength Pareto Evolutionary Algorithm 2 (SPEA2), with final selection by TOPSIS, to maximize oil recovery while minimizing hydraulic losses. The proposed methodology identifies an optimal configuration with a 25.4° vane angle, 3.57 m³/h flow rate, 18.4 % oil fraction, and 0.12 split ratio, achieving a 0.162 oil recovery factor at a pressure drop of 2422 Pa. These findings provide actionable guidelines for VTPS design and operation, facilitating more efficient separation in oilfield applications and demonstrating the AIAD model's efficacy for industrial-scale multiphase flow optimization.
{"title":"Sensitivity and optimization CFD analysis of a vane-type pipe separator based on the AIAD model","authors":"Haokun Zhang , Thomas Höhne","doi":"10.1016/j.ijmultiphaseflow.2025.105510","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105510","url":null,"abstract":"<div><div>Efficient oil-water separation is increasingly vital in mature oilfields, where enhanced water production challenges conventional downhole separation technologies. The vane-type pipe separator (VTPS) offers a promising solution due to its compact configuration and superior phase separation efficiency in constrained environments. However, the inherent complexities of swirling multiphase flow necessitate advanced modeling approaches for performance optimization. In this study, a comprehensive computational framework based on the Algebraic Interfacial Area Density (AIAD) model within an Euler-Euler multiphase context is developed and validated against benchmarked experimental data. Sensitivity analysis employing response surface methodology (RSM) and global-local indices quantifies the influence of key decision parameters, including guide vane installation angle, inlet flow rate, oil fraction, and split ratio, on separator performance. The study elucidates the parametric interplay affecting pressure drop and oil recovery, revealing guide vane angle and oil fraction as the dominant factors for hydraulic and separation performance, respectively. A multi-objective optimization is conducted using the Strength Pareto Evolutionary Algorithm 2 (SPEA2), with final selection by TOPSIS, to maximize oil recovery while minimizing hydraulic losses. The proposed methodology identifies an optimal configuration with a 25.4° vane angle, 3.57 m³/h flow rate, 18.4 % oil fraction, and 0.12 split ratio, achieving a 0.162 oil recovery factor at a pressure drop of 2422 Pa. These findings provide actionable guidelines for VTPS design and operation, facilitating more efficient separation in oilfield applications and demonstrating the AIAD model's efficacy for industrial-scale multiphase flow optimization.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"195 ","pages":"Article 105510"},"PeriodicalIF":3.8,"publicationDate":"2025-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145464040","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 : 2025-10-31DOI: 10.1016/j.ijmultiphaseflow.2025.105503
Kalpana Kumari, Jaya Joshi, Rajeev
This paper addresses a two phase non-linear solidification process characterized by convective initial boundary condition, internal heat generation and surface radiation effects which arise in numerous thermal processes. We considered that the thermal properties such as thermal conductivity, specific heat and speed of phase change materials (PCM) are linearly varying with temperature. This leads to a highly non-linear problem in both solid and mushy zones. We employed the Genocchi wavelet collocation method to solve this complex moving interface problem. We defined the Genocchi Wavelet in interval [a, b], where () with suitable transformations to approximate the solution of phase change model with moving domains. The temperature fields and interface locations are approximated by truncated Genocchi wavelet series. The collocation at appropriate collocation points leads to a system of nonlinear algebraic equations, which are solved numerically to obtain results for temperature distribution and moving phase separation fronts during the solidification process. The exact solution of this problem does not exist. Thus, the results obtained from this method are compared with analytical solution and solution obtained from finite difference method in a special case. The efficiency and accuracy of the proposed method is discussed, which shows that it is suitable for solving the advanced phase change systems under realistic thermal conditions. We explored the influence of convective boundary parameter, radiation parameter, internal heat generation rate,temperature dependent specific heat, speed of PCM and thermal conductivity in accelerating or delaying the phase-change process. It is observed that the specific heat as a function of temperature flow enhances the completion speed of the solidification process. The dimensionless parameter related to the radiation also contributes to the acceleration of the operational time of the solidification process.
{"title":"Genocchi wavelet method for the Stefan problem with dual moving interfaces","authors":"Kalpana Kumari, Jaya Joshi, Rajeev","doi":"10.1016/j.ijmultiphaseflow.2025.105503","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105503","url":null,"abstract":"<div><div>This paper addresses a two phase non-linear solidification process characterized by convective initial boundary condition, internal heat generation and surface radiation effects which arise in numerous thermal processes. We considered that the thermal properties such as thermal conductivity, specific heat and speed of phase change materials (PCM) are linearly varying with temperature. This leads to a highly non-linear problem in both solid and mushy zones. We employed the Genocchi wavelet collocation method to solve this complex moving interface problem. We defined the Genocchi Wavelet in interval [a, b], where (<span><math><mrow><mi>a</mi><mo>≠</mo><mi>b</mi></mrow></math></span>) with suitable transformations to approximate the solution of phase change model with moving domains. The temperature fields and interface locations are approximated by truncated Genocchi wavelet series. The collocation at appropriate collocation points leads to a system of nonlinear algebraic equations, which are solved numerically to obtain results for temperature distribution and moving phase separation fronts during the solidification process. The exact solution of this problem does not exist. Thus, the results obtained from this method are compared with analytical solution and solution obtained from finite difference method in a special case. The efficiency and accuracy of the proposed method is discussed, which shows that it is suitable for solving the advanced phase change systems under realistic thermal conditions. We explored the influence of convective boundary parameter, radiation parameter, internal heat generation rate,temperature dependent specific heat, speed of PCM and thermal conductivity in accelerating or delaying the phase-change process. It is observed that the specific heat as a function of temperature flow enhances the completion speed of the solidification process. The dimensionless parameter related to the radiation also contributes to the acceleration of the operational time of the solidification process.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"195 ","pages":"Article 105503"},"PeriodicalIF":3.8,"publicationDate":"2025-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145464011","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 : 2025-10-30DOI: 10.1016/j.ijmultiphaseflow.2025.105507
Jiarui Xu , Wu Zhou , Tianyi Cai , Luhaibo Zhao
Multi-scale bubbles flow and mass transfer play a critical role in enhancing multiphase reactions, yet accurate real-time visualization and measurement remain challenging. In this work, a bubble detection model is developed to measure bubble size and velocity in real time based on the deep learning algorithm (YOLOv8). To evaluate detection performance and correct size estimation errors, a BubGAN-based synthetic image generation method was employed to create artificial bubbly flow images. At low gas velocities using both 2μm-pore and 10μm-pore generators, the bubble size distributions exhibited bimodal characteristics and increased with rising gas intake. Bubble velocities were determined from displacement and time differences obtained through the detection model. Subsequently, by integrating Higbie’s penetration theory with bubble flow characteristics, a real-time measurement method for multi-scale bubbly flow mass transfer was established and validated through dynamic dissolved oxygen experiments. The results demonstrate that the microbubbles contribute significantly to mass transfer due to their large surface-area-to-volume ratio, while millimeter-sized bubbles enhance gas-liquid mixing and promote the ascent of microbubbles. Overall, the proposed model effectively captures the dynamics of multi-scale bubble flow and mass transfer, elucidates the influence of bubble size on these processes, and provides a foundation for optimizing gas-liquid reactions through real-time bubble size control.
{"title":"Multi-scale bubble flow and mass transfer visual measurements in real time aid with deep learning method","authors":"Jiarui Xu , Wu Zhou , Tianyi Cai , Luhaibo Zhao","doi":"10.1016/j.ijmultiphaseflow.2025.105507","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105507","url":null,"abstract":"<div><div>Multi-scale bubbles flow and mass transfer play a critical role in enhancing multiphase reactions, yet accurate real-time visualization and measurement remain challenging. In this work, a bubble detection model is developed to measure bubble size and velocity in real time based on the deep learning algorithm (YOLOv8). To evaluate detection performance and correct size estimation errors, a BubGAN-based synthetic image generation method was employed to create artificial bubbly flow images. At low gas velocities using both 2μm-pore and 10μm-pore generators, the bubble size distributions exhibited bimodal characteristics and increased with rising gas intake. Bubble velocities were determined from displacement and time differences obtained through the detection model. Subsequently, by integrating Higbie’s penetration theory with bubble flow characteristics, a real-time measurement method for multi-scale bubbly flow mass transfer was established and validated through dynamic dissolved oxygen experiments. The results demonstrate that the microbubbles contribute significantly to mass transfer due to their large surface-area-to-volume ratio, while millimeter-sized bubbles enhance gas-liquid mixing and promote the ascent of microbubbles. Overall, the proposed model effectively captures the dynamics of multi-scale bubble flow and mass transfer, elucidates the influence of bubble size on these processes, and provides a foundation for optimizing gas-liquid reactions through real-time bubble size control.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"195 ","pages":"Article 105507"},"PeriodicalIF":3.8,"publicationDate":"2025-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145464042","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 : 2025-10-30DOI: 10.1016/j.ijmultiphaseflow.2025.105508
Elham Mollaie, Rasool Mohammadi, Mohammad Ali Akhavan-Behabadi, Behrang Sajadi
This study attempts to establish versatile models, based on 30 flow pattern maps available in literature, employing machine learning (ML) methods, within range of database parameters, for adiabatic gas–liquid flow inside small-diameter tubes, from 0.53 to 5.16 mm. Support vector machines (SVM), artificial neural networks (ANN), and histogram-based gradient boosting (HGB) techniques are applied on two separate sets of carefully engineered input features, one with physical dimensional and one with dimensionless parameters, to see if dimensional reduction helps with providing better-performing models. The model training and testing procedure is conducted under a cross-validated study aiming to maximize the performance metric during hyperparameter tuning. The average accuracy of SVM, ANN, and HGB on test sets of data is reported as 0.9284, 0.9240, and 0.9620, respectively based on dimensional features. As for the dimensionless set, in the same order, values of 0.9115, 0.9115, and 0.9583 are obtained, indicating superior performance of HGB, along with acceptable results of ANN and SVM models. ANN models demonstrated faster prediction times than SVM and HGB, which makes ANN models more favorable for high-quantity prediction procedures. HGB models showed more robustness, while the SVM models showed the most prediction uncertainty amongst the models. Also, to visualize the model’s performance, several flow pattern maps are reconstructed with all models. Overall, due to the variety of flow behavior types in the database, employing sets of dimensionless numbers does not secure developing more general models and the performance for different input feature sets is roughly on par.
{"title":"Applied machine learning for adiabatic gas–liquid flow pattern prediction in small diameter circular tubes: Effect of dimensionality reduction","authors":"Elham Mollaie, Rasool Mohammadi, Mohammad Ali Akhavan-Behabadi, Behrang Sajadi","doi":"10.1016/j.ijmultiphaseflow.2025.105508","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105508","url":null,"abstract":"<div><div>This study attempts to establish versatile models, based on 30 flow pattern maps available in literature, employing machine learning (ML) methods, within range of database parameters, for adiabatic gas–liquid flow inside small-diameter tubes, from 0.53 to 5.16 mm. Support vector machines (SVM), artificial neural networks (ANN), and histogram-based gradient boosting (HGB) techniques are applied on two separate sets of carefully engineered input features, one with physical dimensional and one with dimensionless parameters, to see if dimensional reduction helps with providing better-performing models. The model training and testing procedure is conducted under a cross-validated study aiming to maximize the performance metric during hyperparameter tuning. The average accuracy of SVM, ANN, and HGB on test sets of data is reported as 0.9284, 0.9240, and 0.9620, respectively based on dimensional features. As for the dimensionless set, in the same order, values of 0.9115, 0.9115, and 0.9583 are obtained, indicating superior performance of HGB, along with acceptable results of ANN and SVM models. ANN models demonstrated faster prediction times than SVM and HGB, which makes ANN models more favorable for high-quantity prediction procedures. HGB models showed more robustness, while the SVM models showed the most prediction uncertainty amongst the models. Also, to visualize the model’s performance, several flow pattern maps are reconstructed with all models. Overall, due to the variety of flow behavior types in the database, employing sets of dimensionless numbers does not secure developing more general models and the performance for different input feature sets is roughly on par.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"195 ","pages":"Article 105508"},"PeriodicalIF":3.8,"publicationDate":"2025-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145464111","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 : 2025-10-30DOI: 10.1016/j.ijmultiphaseflow.2025.105506
Hong-Wei Xiao, Jie Wu
The present study examines the impact behavior of air-in-liquid compound droplets on curved surfaces using a numerical approach. By integrating the lattice Boltzmann method (LBM) for multiphase flow modeling and the immersed boundary method (IBM) for fluid-substrate interactions, we systematically investigate the influence of surface diameter and inner bubble size on the dynamics of droplet impact. Key parameters analyzed include liquid film thickness, bubble deformation, splash morphology, rupture mechanisms, impact force and pressure. Our findings reveal several significant conclusions: (1) Surface diameter and inner bubble size exhibit opposing effects on splash length and cavity formation. (2) The splashing angle at rupture is correlated with single-phase droplet behavior and surface diameter, showing minimal dependence on bubble size. (3) Three distinct rupture mechanisms emerge during the spreading phase, influenced by interactions between surface diameter and inner bubble size, with potential hybrid manifestations observed. (4) The maximum impact force is primarily determined by inner bubble size, with smaller bubbles demonstrating enhanced impact buffering capabilities. (5) The developed models for maximum impact force and pressure show excellent agreement with numerical simulations. These findings provide valuable insights into the control of droplet dynamics, offering practical applications in fields ranging from spray coating to biomedical engineering.
{"title":"Impact of air-in-liquid compound droplet on a curved surface","authors":"Hong-Wei Xiao, Jie Wu","doi":"10.1016/j.ijmultiphaseflow.2025.105506","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105506","url":null,"abstract":"<div><div>The present study examines the impact behavior of air-in-liquid compound droplets on curved surfaces using a numerical approach. By integrating the lattice Boltzmann method (LBM) for multiphase flow modeling and the immersed boundary method (IBM) for fluid-substrate interactions, we systematically investigate the influence of surface diameter and inner bubble size on the dynamics of droplet impact. Key parameters analyzed include liquid film thickness, bubble deformation, splash morphology, rupture mechanisms, impact force and pressure. Our findings reveal several significant conclusions: (1) Surface diameter and inner bubble size exhibit opposing effects on splash length and cavity formation. (2) The splashing angle at rupture is correlated with single-phase droplet behavior and surface diameter, showing minimal dependence on bubble size. (3) Three distinct rupture mechanisms emerge during the spreading phase, influenced by interactions between surface diameter and inner bubble size, with potential hybrid manifestations observed. (4) The maximum impact force is primarily determined by inner bubble size, with smaller bubbles demonstrating enhanced impact buffering capabilities. (5) The developed models for maximum impact force and pressure show excellent agreement with numerical simulations. These findings provide valuable insights into the control of droplet dynamics, offering practical applications in fields ranging from spray coating to biomedical engineering.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"195 ","pages":"Article 105506"},"PeriodicalIF":3.8,"publicationDate":"2025-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145464012","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 : 2025-10-30DOI: 10.1016/j.ijmultiphaseflow.2025.105505
Davide Procacci , Arturo A. Arosemena , Simone Di Giorgio , Jannike Solsvik
The effect of buoyant bubbles – undergoing deformation, breakup, and coalescence – on wall-bounded turbulence is explored through numerical simulations of a bubbly channel flow in an upwards configuration. We show that the dispersed phase drastically changes the turbulence intensities. In particular, we demonstrate that while bubbles increase anisotropy in the core region, most of the channel exhibits a higher degree of isotropy compared to the single-phase flow. We attribute this energy redistribution to an increase in sweeps, driven by the turbulent wakes and shear layers generated by the largest bubbles. These findings pave the way for a better understanding of bubble-laden flows and offer valuable data for validating Reynolds stress models.
{"title":"Turbulence anisotropy modulation in bubble-laden channel flow: A numerical study","authors":"Davide Procacci , Arturo A. Arosemena , Simone Di Giorgio , Jannike Solsvik","doi":"10.1016/j.ijmultiphaseflow.2025.105505","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105505","url":null,"abstract":"<div><div>The effect of buoyant bubbles – undergoing deformation, breakup, and coalescence – on wall-bounded turbulence is explored through numerical simulations of a bubbly channel flow in an upwards configuration. We show that the dispersed phase drastically changes the turbulence intensities. In particular, we demonstrate that while bubbles increase anisotropy in the core region, most of the channel exhibits a higher degree of isotropy compared to the single-phase flow. We attribute this energy redistribution to an increase in sweeps, driven by the turbulent wakes and shear layers generated by the largest bubbles. These findings pave the way for a better understanding of bubble-laden flows and offer valuable data for validating Reynolds stress models.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"195 ","pages":"Article 105505"},"PeriodicalIF":3.8,"publicationDate":"2025-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145414611","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 : 2025-10-28DOI: 10.1016/j.ijmultiphaseflow.2025.105504
Long Ju , Chunyu Zhang , Bicheng Yan , Shuyu Sun
This paper proposes a lattice Boltzmann (LB) wetting boundary processing scheme for binary flow with large density ratios. The greatest advantage of the proposed method is that the implementation of contact line motion can be significantly simplified while still maintaining good accuracy and locality. For this purpose, the order parameter gradient at the boundary node is derived by combining the wetting boundary conditions in the form of free energy with the form of geometry, and the information of the contact angle is explicitly incorporated into the expression of the chemical potential, thus avoiding complicated interpolations for irregular geometries. In addition, by introducing free parameters, the relaxation time is decoupled from the viscosity, thereby enhancing the numerical stability of the scheme under conditions of high Reynolds numbers. Several numerical testing cases are conducted, including wetting processes on straight and curved boundaries. The results demonstrate that the proposed method has good ability and satisfactory accuracy to simulate contact line motions.
{"title":"Phase-field based lattice Boltzmann modeling of contact angles in binary flow with large density ratios","authors":"Long Ju , Chunyu Zhang , Bicheng Yan , Shuyu Sun","doi":"10.1016/j.ijmultiphaseflow.2025.105504","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105504","url":null,"abstract":"<div><div>This paper proposes a lattice Boltzmann (LB) wetting boundary processing scheme for binary flow with large density ratios. The greatest advantage of the proposed method is that the implementation of contact line motion can be significantly simplified while still maintaining good accuracy and locality. For this purpose, the order parameter gradient at the boundary node is derived by combining the wetting boundary conditions in the form of free energy with the form of geometry, and the information of the contact angle is explicitly incorporated into the expression of the chemical potential, thus avoiding complicated interpolations for irregular geometries. In addition, by introducing free parameters, the relaxation time is decoupled from the viscosity, thereby enhancing the numerical stability of the scheme under conditions of high Reynolds numbers. Several numerical testing cases are conducted, including wetting processes on straight and curved boundaries. The results demonstrate that the proposed method has good ability and satisfactory accuracy to simulate contact line motions.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"195 ","pages":"Article 105504"},"PeriodicalIF":3.8,"publicationDate":"2025-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145414686","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}
<div><div>Convection-driven separation in binary fluid mixtures is crucial in applications ranging from geothermal energy to chemical processing. However, prior studies have largely neglected the combined influence of the Soret and Dufour effects on species redistribution. This paper investigates convection-driven separation in a binary fluid mixture within a porous medium, incorporating the Soret effect and, for the first time, systematically evaluating the influence of the Dufour effect. Using a combination of analytical and numerical methods, this study assesses the impact of the Dufour parameter on both the onset of convection and the resulting species separation within a shallow porous cavity. Linear and nonlinear analyses are employed to determine thresholds for stationary, oscillatory, and subcritical bifurcations with respect to key parameters: the Dufour number (<span><math><mrow><mi>D</mi><mi>f</mi></mrow></math></span>), the separation ratio (<span><math><mi>φ</mi></math></span>), the Lewis number (<span><math><mrow><mi>L</mi><mi>e</mi></mrow></math></span>), the thermal Rayleigh number (<span><math><msub><mi>R</mi><mi>T</mi></msub></math></span>), and the Darcy number (<span><math><mrow><mi>D</mi><mi>a</mi></mrow></math></span>). An analytical solution based on the parallel flow approximation is developed and validated numerically using a finite-difference method to evaluate species separation and heat transfer characteristics. Three regimes are examined: Darcy, Brinkman, and pure fluid media. The analysis spans a wide range of Lewis numbers (<span><math><mrow><mi>L</mi><mi>e</mi></mrow></math></span> = 0.1 to 100), covering gases, hydrocarbon fuels, and salt-water solutions. Results show that the Dufour effect significantly influences species separation in gaseous mixtures, while its impact on liquid mixtures is negligible. The findings demonstrate that within the Darcy regime, low permeability effectively suppresses convective flows, thereby enhancing species separation more effectively than in the Brinkman or pure fluid regimes, where higher permeability promotes stronger convection and reduces separation efficiency. Moreover, a low-permeability Darcy medium, combined with a negative Dufour number and minimal thermal gradients, provides the most favorable conditions for maximizing species separation. Results show that for <span><math><mrow><mi>L</mi><mi>e</mi><mo>=</mo><mn>2</mn></mrow></math></span>, 10 and 100, increasing <span><math><mrow><mi>D</mi><mi>f</mi></mrow></math></span> from -0.2 to 0.2 reduces species separation by <span><math><mrow><mn>23.15</mn><mo>%</mo><mo>,</mo></mrow></math></span> <span><math><mrow><mn>9</mn><mo>%</mo></mrow></math></span> and <span><math><mrow><mn>0.00</mn><mo>%</mo><mo>,</mo></mrow></math></span> respectively. This confirms the minimal impact of the Dufour effect on liquid mixtures (high <span><math><mrow><mi>L</mi><mi>e</mi></mrow></math></span>). Negative <span><math><mrow><mi>D</mi><mi>f</
{"title":"Influence of the dufour effect on soret-driven species separation in binary mixtures: A comparative numerical and analytical study across porous flow regimes","authors":"Ismail Filahi , Layla Foura , Mohamed Bourich , Youssef Dahani , Safae Hasnaoui , Abdelfattah El Mansouri , Abdelkhalek Amahmid , Mohammed Hasnaoui","doi":"10.1016/j.ijmultiphaseflow.2025.105501","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105501","url":null,"abstract":"<div><div>Convection-driven separation in binary fluid mixtures is crucial in applications ranging from geothermal energy to chemical processing. However, prior studies have largely neglected the combined influence of the Soret and Dufour effects on species redistribution. This paper investigates convection-driven separation in a binary fluid mixture within a porous medium, incorporating the Soret effect and, for the first time, systematically evaluating the influence of the Dufour effect. Using a combination of analytical and numerical methods, this study assesses the impact of the Dufour parameter on both the onset of convection and the resulting species separation within a shallow porous cavity. Linear and nonlinear analyses are employed to determine thresholds for stationary, oscillatory, and subcritical bifurcations with respect to key parameters: the Dufour number (<span><math><mrow><mi>D</mi><mi>f</mi></mrow></math></span>), the separation ratio (<span><math><mi>φ</mi></math></span>), the Lewis number (<span><math><mrow><mi>L</mi><mi>e</mi></mrow></math></span>), the thermal Rayleigh number (<span><math><msub><mi>R</mi><mi>T</mi></msub></math></span>), and the Darcy number (<span><math><mrow><mi>D</mi><mi>a</mi></mrow></math></span>). An analytical solution based on the parallel flow approximation is developed and validated numerically using a finite-difference method to evaluate species separation and heat transfer characteristics. Three regimes are examined: Darcy, Brinkman, and pure fluid media. The analysis spans a wide range of Lewis numbers (<span><math><mrow><mi>L</mi><mi>e</mi></mrow></math></span> = 0.1 to 100), covering gases, hydrocarbon fuels, and salt-water solutions. Results show that the Dufour effect significantly influences species separation in gaseous mixtures, while its impact on liquid mixtures is negligible. The findings demonstrate that within the Darcy regime, low permeability effectively suppresses convective flows, thereby enhancing species separation more effectively than in the Brinkman or pure fluid regimes, where higher permeability promotes stronger convection and reduces separation efficiency. Moreover, a low-permeability Darcy medium, combined with a negative Dufour number and minimal thermal gradients, provides the most favorable conditions for maximizing species separation. Results show that for <span><math><mrow><mi>L</mi><mi>e</mi><mo>=</mo><mn>2</mn></mrow></math></span>, 10 and 100, increasing <span><math><mrow><mi>D</mi><mi>f</mi></mrow></math></span> from -0.2 to 0.2 reduces species separation by <span><math><mrow><mn>23.15</mn><mo>%</mo><mo>,</mo></mrow></math></span> <span><math><mrow><mn>9</mn><mo>%</mo></mrow></math></span> and <span><math><mrow><mn>0.00</mn><mo>%</mo><mo>,</mo></mrow></math></span> respectively. This confirms the minimal impact of the Dufour effect on liquid mixtures (high <span><math><mrow><mi>L</mi><mi>e</mi></mrow></math></span>). Negative <span><math><mrow><mi>D</mi><mi>f</","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"195 ","pages":"Article 105501"},"PeriodicalIF":3.8,"publicationDate":"2025-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145414687","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 : 2025-10-27DOI: 10.1016/j.ijmultiphaseflow.2025.105499
Faraz Salimnezhad, Metin Muradoglu
Evaporation of a deformable droplet under convection is investigated and performance of the classical and Abramzon–Sirignano (A–S) models is evaluated. Using the Immersed Boundary/Front-Tracking (IB/FT) method, interface-resolved simulations are performed to examine droplet evaporation dynamics over a wide range of Reynolds (), Weber (), and mass transfer () numbers. It is shown that flow in the wake region is greatly influenced by the Stefan flow as higher evaporation rates leads to an earlier flow separation and a larger recirculation zone behind the droplet. Under strong convection, the models fail to capture the evaporation rate especially in the wake region, which leads to significant discrepancies compared to interface-resolved simulations. Droplet deformation greatly influences the flow field around the droplet and generally enhances evaporation but the evaporation rate remains well correlated with the surface area. The A–S model exhibits a reasonably good performance for a nearly spherical droplet but its performance deteriorates significantly and generally underpredicts evaporation rate as droplet deformation increases. The A–S model is overall found to outperform the classical model in the presence of significant convection.
{"title":"Computational investigation of deformable droplet evaporation under forced convection","authors":"Faraz Salimnezhad, Metin Muradoglu","doi":"10.1016/j.ijmultiphaseflow.2025.105499","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105499","url":null,"abstract":"<div><div>Evaporation of a deformable droplet under convection is investigated and performance of the classical and Abramzon–Sirignano (A–S) models is evaluated. Using the Immersed Boundary/Front-Tracking (IB/FT) method, interface-resolved simulations are performed to examine droplet evaporation dynamics over a wide range of Reynolds (<span><math><mrow><mn>20</mn><mo>≤</mo><mi>R</mi><mi>e</mi><mo>≤</mo><mn>200</mn></mrow></math></span>), Weber (<span><math><mrow><mn>0</mn><mo>.</mo><mn>65</mn><mo>≤</mo><mi>W</mi><mi>e</mi><mo>≤</mo><mn>9</mn></mrow></math></span>), and mass transfer (<span><math><mrow><mn>1</mn><mo>≤</mo><msub><mrow><mi>B</mi></mrow><mrow><mi>M</mi></mrow></msub><mo>≤</mo><mn>15</mn></mrow></math></span>) numbers. It is shown that flow in the wake region is greatly influenced by the Stefan flow as higher evaporation rates leads to an earlier flow separation and a larger recirculation zone behind the droplet. Under strong convection, the models fail to capture the evaporation rate especially in the wake region, which leads to significant discrepancies compared to interface-resolved simulations. Droplet deformation greatly influences the flow field around the droplet and generally enhances evaporation but the evaporation rate remains well correlated with the surface area. The A–S model exhibits a reasonably good performance for a nearly spherical droplet but its performance deteriorates significantly and generally underpredicts evaporation rate as droplet deformation increases. The A–S model is overall found to outperform the classical model in the presence of significant convection.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"195 ","pages":"Article 105499"},"PeriodicalIF":3.8,"publicationDate":"2025-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145414605","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 : 2025-10-24DOI: 10.1016/j.ijmultiphaseflow.2025.105498
Jongsu Jeong, Seungho Kim
While droplet rebound is typically observed on hydrophobic or textured surfaces, this study provides experimental and numerical evidence that, consistent with prior studies, smooth superhydrophilic surfaces can exhibit bouncing when a thin intervening air film remains intact during impact. Through a combination of experiments, numerical simulations, and theoretical modeling, we show that the persistence of this air film plays a critical role in governing the rebound dynamics. High-speed imaging and interferometry reveal three distinct regimes — bouncing, partial bouncing, and spreading — depending on impact conditions. A key parameter identified is the lifetime of the air film, which has hitherto been unreported and is experimentally found to decrease as impact inertia increases. We develop a scaling model based on fluid–structure interaction within the gas layer, predicting the rupturetime scale of air film that sensitively depends on the Weber number. The rupture time derived from this model shows agreement with experimental measurements, thereby capturing the overall experimental trends. Using this model, three regimes can be identified by rupture timing: bouncing when no rupture occurs during contact, partial bouncing when rupture occurs near the end of contact, and spreading when rupture occurs almost immediately. These findings highlight the central role of air film dynamics in rebound behavior on superhydrophilic surfaces and might suggest design principles for controlling liquid repellency through vapor-phase engineering.
{"title":"Air film-mediated drop bouncing on superhydrophilic surfaces","authors":"Jongsu Jeong, Seungho Kim","doi":"10.1016/j.ijmultiphaseflow.2025.105498","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105498","url":null,"abstract":"<div><div>While droplet rebound is typically observed on hydrophobic or textured surfaces, this study provides experimental and numerical evidence that, consistent with prior studies, smooth superhydrophilic surfaces can exhibit bouncing when a thin intervening air film remains intact during impact. Through a combination of experiments, numerical simulations, and theoretical modeling, we show that the persistence of this air film plays a critical role in governing the rebound dynamics. High-speed imaging and interferometry reveal three distinct regimes — bouncing, partial bouncing, and spreading — depending on impact conditions. A key parameter identified is the lifetime of the air film, which has hitherto been unreported and is experimentally found to decrease as impact inertia increases. We develop a scaling model based on fluid–structure interaction within the gas layer, predicting the rupturetime scale of air film that sensitively depends on the Weber number. The rupture time derived from this model shows agreement with experimental measurements, thereby capturing the overall experimental trends. Using this model, three regimes can be identified by rupture timing: bouncing when no rupture occurs during contact, partial bouncing when rupture occurs near the end of contact, and spreading when rupture occurs almost immediately. These findings highlight the central role of air film dynamics in rebound behavior on superhydrophilic surfaces and might suggest design principles for controlling liquid repellency through vapor-phase engineering.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"195 ","pages":"Article 105498"},"PeriodicalIF":3.8,"publicationDate":"2025-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145371329","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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