Pub Date : 2026-04-01Epub Date: 2026-02-05DOI: 10.1016/j.ijmultiphaseflow.2026.105645
Peize Han , Zhengqiao Chen , Penghui Ma , Wei Tan , Guorui Zhu
The development of efficient and compact shell-and-tube heat exchangers has brought flow-induced vibrations in tube bundles into the spotlight. Comprehending the two-phase flow regimes within tube bundles and their associated fluid-induced excitation is crucial for exploring flow-induced vibrations. However, the complexity of two-phase flow between tube bundles and the difficulty in measuring fluid forces pose significant challenges to flow regime identification and fluid excitation studies. In this study, a flow regime identification system was developed by utilizing a flow pressure testing device. The dynamic fluid forces exerted by air-water two-phase flow on horizontal tube bundles under diverse conditions were analyzed. The flow regimes between tube bundles were identified and classified by combining images with wavelet analysis of the fluid pressure around the tubes. Wavelet analysis effectively extracts local features from non-stationary fluid pressure signals, enabling the newly developed flow regime recognition system to achieve higher accuracy and enhancing the analysis of flow field pressure. Furthermore, time-domain and frequency-domain analyses characterized the fluid forces acting on the tube bundle across different flow regimes. The results revealed that the drag force is predominantly governed by large-scale flow structures, while the lift force is sensitive to local dynamic variations. Their dynamic evolution fundamentally arises from non-monotonic changes in flow regime structure, turbulence intensity, and fluid-structure interaction strength induced by varying flow conditions. Envelope spectra were then constructed to determine the fluid force spectral characteristics for each flow regime. This work advances research on flow regime identification and flow-induced vibration prediction for shell-and-tube heat exchanger design and operation.
{"title":"Flow regime identification and fluid dynamic forces in two-phase flow through staggered tube bundles","authors":"Peize Han , Zhengqiao Chen , Penghui Ma , Wei Tan , Guorui Zhu","doi":"10.1016/j.ijmultiphaseflow.2026.105645","DOIUrl":"10.1016/j.ijmultiphaseflow.2026.105645","url":null,"abstract":"<div><div>The development of efficient and compact shell-and-tube heat exchangers has brought flow-induced vibrations in tube bundles into the spotlight. Comprehending the two-phase flow regimes within tube bundles and their associated fluid-induced excitation is crucial for exploring flow-induced vibrations. However, the complexity of two-phase flow between tube bundles and the difficulty in measuring fluid forces pose significant challenges to flow regime identification and fluid excitation studies. In this study, a flow regime identification system was developed by utilizing a flow pressure testing device. The dynamic fluid forces exerted by air-water two-phase flow on horizontal tube bundles under diverse conditions were analyzed. The flow regimes between tube bundles were identified and classified by combining images with wavelet analysis of the fluid pressure around the tubes. Wavelet analysis effectively extracts local features from non-stationary fluid pressure signals, enabling the newly developed flow regime recognition system to achieve higher accuracy and enhancing the analysis of flow field pressure. Furthermore, time-domain and frequency-domain analyses characterized the fluid forces acting on the tube bundle across different flow regimes. The results revealed that the drag force is predominantly governed by large-scale flow structures, while the lift force is sensitive to local dynamic variations. Their dynamic evolution fundamentally arises from non-monotonic changes in flow regime structure, turbulence intensity, and fluid-structure interaction strength induced by varying flow conditions. Envelope spectra were then constructed to determine the fluid force spectral characteristics for each flow regime. This work advances research on flow regime identification and flow-induced vibration prediction for shell-and-tube heat exchanger design and operation.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"198 ","pages":"Article 105645"},"PeriodicalIF":3.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146186580","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 : 2026-04-01Epub Date: 2025-09-15DOI: 10.1016/j.ijmultiphaseflow.2025.105430
Sean J. Perkins
Elongated bubble centring—an obscure counter-buoyant phenomenon encountered in horizontal gas-liquid slug flow—is correlated with liquid viscosity and their connection is theorized. Extracting from three sets of high-viscosity liquid (HVL) photographic data with and , the degree of incurred centring is found to increase, generally, in proportion to for a wide range of operational rates as evidenced through measurements at bubble nose, body and tail. It is demonstrated that full and nearly-symmetric centring can occur in HVL-containing flows—the former at relatively low inertial supply in contradiction to water-based dynamics. Qualitative advancements regarding the mechanistic nature of bubble centring and its plausible function within flow pattern transition theory are presented. Elaborating on recent modelling efforts, four distinct hypotheses are formulated: 1) film region laminarity as a modulator for centring; 2) boundary layer theory in slug flow to differentiate an outer-layer, relative motion-dominated film flow necessary for the initiation of centring; 3) wedge theory—a plausible alternative mechanism for partial-centring; and 4) a novel framework for the slug-annular transition composed of two unique mechanisms—centring and coalescence. The postulated boundary layer theory is investigated using a calibrated case of HVL slug flow and a dynamical environment conducive to centring mechanism proliferation is calculated.
{"title":"Elongated bubble centring and high-viscosity liquids in horizontal gas-liquid slug flow: Empirical analyses and novel theory","authors":"Sean J. Perkins","doi":"10.1016/j.ijmultiphaseflow.2025.105430","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105430","url":null,"abstract":"<div><div>Elongated bubble centring—an obscure counter-buoyant phenomenon encountered in horizontal gas-liquid slug flow—is correlated with liquid viscosity and their connection is theorized. Extracting from three sets of high-viscosity liquid (HVL) photographic data with <span><math><mrow><msub><mrow><mi>μ</mi></mrow><mrow><mstyle><mi>L</mi></mstyle></mrow></msub><mo>∈</mo><mrow><mo>[</mo><mn>1</mn><mo>,</mo><mn>960</mn><mo>]</mo></mrow><mspace></mspace><mstyle><mi>m</mi><mi>P</mi><mi>a</mi></mstyle><mspace></mspace><mstyle><mi>s</mi></mstyle></mrow></math></span> and <span><math><mrow><mi>D</mi><mo>∈</mo><mrow><mo>[</mo><mn>20</mn><mo>,</mo><mn>50</mn><mo>.</mo><mn>8</mn><mo>]</mo></mrow><mspace></mspace><mstyle><mi>m</mi><mi>m</mi></mstyle></mrow></math></span>, the degree of incurred centring is found to increase, generally, in proportion to <span><math><msub><mrow><mi>μ</mi></mrow><mrow><mstyle><mi>L</mi></mstyle></mrow></msub></math></span> for a wide range of operational rates as evidenced through measurements at bubble nose, body and tail. It is demonstrated that full and nearly-symmetric centring can occur in HVL-containing flows—the former at relatively low inertial supply in contradiction to water-based dynamics. Qualitative advancements regarding the mechanistic nature of bubble centring and its plausible function within flow pattern transition theory are presented. Elaborating on recent modelling efforts, four distinct hypotheses are formulated: 1) film region laminarity as a modulator for centring; 2) boundary layer theory in slug flow to differentiate an outer-layer, relative motion-dominated film flow necessary for the initiation of centring; 3) wedge theory—a plausible alternative mechanism for partial-centring; and 4) a novel framework for the slug-annular transition composed of two unique mechanisms—centring and coalescence. The postulated boundary layer theory is investigated using a calibrated case of HVL slug flow and a dynamical environment conducive to centring mechanism proliferation is calculated.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"198 ","pages":"Article 105430"},"PeriodicalIF":3.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146186564","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 : 2026-04-01Epub Date: 2026-01-12DOI: 10.1016/j.ijmultiphaseflow.2026.105616
Arseniy Parfenov, Alexander Gelfgat, Neima Brauner
Instability of a stratified two-phase MHD parallel flow between two infinite plates is addressed. We examine the effect of the transverse magnetic field on the base flow and long wave instability of a two-layer system consisting of conductive liquid and non-conductive gas. Both perfectly insulating and perfectly conducting boundaries are considered. To capture the behavior at small but finite wavenumbers, the conventional first-order long-wave stability analysis is extended to higher order terms. Using mercury-air system as a representative test case, the results demonstrate distinct and non-similar base flow and disturbance profiles, as well as different stability maps for insulating versus conducting boundaries. The stability diagrams reveal a non-monotonic influence of the magnetic field on flow stability, showing that, in addition to its expected stabilizing effect, the field can also induce destabilization under certain conditions. Inspection of the disturbance profiles indicates that despite the strong damping of mercury flow by the magnetic field, interaction of the two fluids at the interface and the shear-induced instabilities in the gas layer dominate and can lead to flow destabilization as the magnetic field strength increases.
{"title":"Long-wave instability of stratified two-phase MHD channel flow","authors":"Arseniy Parfenov, Alexander Gelfgat, Neima Brauner","doi":"10.1016/j.ijmultiphaseflow.2026.105616","DOIUrl":"10.1016/j.ijmultiphaseflow.2026.105616","url":null,"abstract":"<div><div>Instability of a stratified two-phase MHD parallel flow between two infinite plates is addressed. We examine the effect of the transverse magnetic field on the base flow and long wave instability of a two-layer system consisting of conductive liquid and non-conductive gas. Both perfectly insulating and perfectly conducting boundaries are considered. To capture the behavior at small but finite wavenumbers, the conventional first-order long-wave stability analysis is extended to higher order terms. Using mercury-air system as a representative test case, the results demonstrate distinct and non-similar base flow and disturbance profiles, as well as different stability maps for insulating versus conducting boundaries. The stability diagrams reveal a non-monotonic influence of the magnetic field on flow stability, showing that, in addition to its expected stabilizing effect, the field can also induce destabilization under certain conditions. Inspection of the disturbance profiles indicates that despite the strong damping of mercury flow by the magnetic field, interaction of the two fluids at the interface and the shear-induced instabilities in the gas layer dominate and can lead to flow destabilization as the magnetic field strength increases.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"198 ","pages":"Article 105616"},"PeriodicalIF":3.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146186629","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 : 2026-03-01Epub Date: 2026-01-06DOI: 10.1016/j.ijmultiphaseflow.2026.105607
Longxiang Huang , Benjamin Duret , François-Xavier Demoulin
This study investigates the relationship between three-dimensional liquid structures and their two-dimensional projections using curvature analysis. Liquid structures are generated via a direct numerical simulation (DNS) solver for two-phase flow, and their two-dimensional projections are obtained by accumulating the Volume-of-Fluid field onto a single plane, simulating an imaging process. Curvature analysis is applied to both the three-dimensional data and the projected images across a range of Weber numbers and liquid volume fractions. Representative test cases illustrate the influence of structural superposition within this framework. Results indicate that, despite inherent projection-related biases, the curvature distributions derived from two-dimensional projections effectively capture the morphological characteristics of the original three-dimensional shapes. Key geometric features remain largely consistent across varied flow conditions. This work demonstrates the reliability of curvature-based image post-processing and outlines future pathways for integrating experimental imaging with numerical simulations under a unified curvature-analysis framework.
{"title":"Curvature analysis of the projections of the 3D liquid structures","authors":"Longxiang Huang , Benjamin Duret , François-Xavier Demoulin","doi":"10.1016/j.ijmultiphaseflow.2026.105607","DOIUrl":"10.1016/j.ijmultiphaseflow.2026.105607","url":null,"abstract":"<div><div>This study investigates the relationship between three-dimensional liquid structures and their two-dimensional projections using curvature analysis. Liquid structures are generated via a direct numerical simulation (DNS) solver for two-phase flow, and their two-dimensional projections are obtained by accumulating the Volume-of-Fluid field onto a single plane, simulating an imaging process. Curvature analysis is applied to both the three-dimensional data and the projected images across a range of Weber numbers and liquid volume fractions. Representative test cases illustrate the influence of structural superposition within this framework. Results indicate that, despite inherent projection-related biases, the curvature distributions derived from two-dimensional projections effectively capture the morphological characteristics of the original three-dimensional shapes. Key geometric features remain largely consistent across varied flow conditions. This work demonstrates the reliability of curvature-based image post-processing and outlines future pathways for integrating experimental imaging with numerical simulations under a unified curvature-analysis framework.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"197 ","pages":"Article 105607"},"PeriodicalIF":3.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145974414","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 : 2026-03-01Epub Date: 2026-01-21DOI: 10.1016/j.ijmultiphaseflow.2026.105626
Michał Rajek , Jacek Pozorski
Large eddy simulations (LES) of isotropic turbulence coupled with the Lagrangian particle tracking have been consistently disregarded as a means of exploring the physics underlying turbulent dispersed two-phase flows with a fully developed inertial subrange. In the present work, we determine the impact of our recently developed adaptively reconstructed spectral eddy-viscosity on the dynamics of small, heavy inertial particles at high Reynolds numbers. We use the particle number density spectrum to assess the ability of LES to predict particle clustering at distances exceeding the Kolmogorov length scale. We demonstrate that the functional form of the spectral eddy-viscosity has in general a moderate impact on the quantitative prediction of this phenomenon, while preserving qualitative agreement between LES and reference direct numerical simulations (DNS). By comparing the results against a state-of-the-art point-particle DNS, we demonstrate that the adaptively reconstructed closure enhances the predictive capabilities of LES for a wide range of Stokes and Reynolds numbers, providing the opportunity to explore the inertial-range clustering of dispersed particles over a broad spectrum of length scales. We point out that, assuming sufficient spatial resolution, the LES enriched with the proposed spectral eddy-viscosity becomes a reliable method for exploring the influence of large, energy-containing flow scales on the dynamics of inertial particles suspended in isotropic turbulence, particularly at Reynolds numbers that are currently unachievable in DNS. We further argue that this approach can support ongoing efforts to develop theories concerning the turbulent transport of dispersed particles.
{"title":"Adaptively reconstructed spectral eddy-viscosity in large eddy simulations of particle-laden isotropic turbulence, Part II: Number density spectra and inertial range clustering","authors":"Michał Rajek , Jacek Pozorski","doi":"10.1016/j.ijmultiphaseflow.2026.105626","DOIUrl":"10.1016/j.ijmultiphaseflow.2026.105626","url":null,"abstract":"<div><div>Large eddy simulations (LES) of isotropic turbulence coupled with the Lagrangian particle tracking have been consistently disregarded as a means of exploring the physics underlying turbulent dispersed two-phase flows with a fully developed inertial subrange. In the present work, we determine the impact of our recently developed adaptively reconstructed spectral eddy-viscosity on the dynamics of small, heavy inertial particles at high Reynolds numbers. We use the particle number density spectrum to assess the ability of LES to predict particle clustering at distances exceeding the Kolmogorov length scale. We demonstrate that the functional form of the spectral eddy-viscosity has in general a moderate impact on the quantitative prediction of this phenomenon, while preserving qualitative agreement between LES and reference direct numerical simulations (DNS). By comparing the results against a state-of-the-art point-particle DNS, we demonstrate that the adaptively reconstructed closure enhances the predictive capabilities of LES for a wide range of Stokes and Reynolds numbers, providing the opportunity to explore the inertial-range clustering of dispersed particles over a broad spectrum of length scales. We point out that, assuming sufficient spatial resolution, the LES enriched with the proposed spectral eddy-viscosity becomes a reliable method for exploring the influence of large, energy-containing flow scales on the dynamics of inertial particles suspended in isotropic turbulence, particularly at Reynolds numbers that are currently unachievable in DNS. We further argue that this approach can support ongoing efforts to develop theories concerning the turbulent transport of dispersed particles.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"197 ","pages":"Article 105626"},"PeriodicalIF":3.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146170489","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 : 2026-03-01Epub Date: 2026-01-28DOI: 10.1016/j.ijmultiphaseflow.2026.105634
Abdullah M. Abdal , Debashis Panda , Lyes Kahouadji , Mosayeb Shams , Seungwon Shin , Jalel Chergui , Damir Juric , Omar K. Matar
We perform three-dimensional simulations of miscible and immiscible displacements in a cylindrical pipe. For the miscible case, both laminar and turbulent displacement regimes are considered, and our numerical framework uses direct numerical simulation (DNS) and a Large Eddy Simulation (LES) approach based on a Lilly–Smagorinsky model. The dynamics of the flow are governed by the Navier–Stokes equations, coupled with a convective-diffusion equation for the concentration of the more viscous fluid when considering the miscible cases. For the immiscible laminar cases, we perform two-phase DNS considering both pinned and moving contact lines to capture the full range of immiscible dynamic behaviours. The pinned contact line reflects stationary interfaces constrained by surface heterogeneity, while the moving contact line accounts for dynamic interfacial motion influenced by viscous and capillary forces. This study shows that the viscosity contrasts between the two fluids play a significant role in determining the efficiency of ‘cleaning’ of a pipe containing an initially highly viscous resident fluid. When the viscosity of the displaced fluid is low, the laminar displacement flow is efficient in cleaning the pipe; however, when the viscosity increases, the laminar displacement becomes inadequate. Our numerical predictions in the turbulent regime showed that more efficient cleaning is achieved when the viscosity contrast between the two fluids is large. Lastly, our results reveal that the dynamics of a moving contact line can impact both the efficiency and the pattern of cleaning within the pipe.
{"title":"Three-dimensional numerical simulations of product changeover: Miscible and immiscible displacements in circular tubes","authors":"Abdullah M. Abdal , Debashis Panda , Lyes Kahouadji , Mosayeb Shams , Seungwon Shin , Jalel Chergui , Damir Juric , Omar K. Matar","doi":"10.1016/j.ijmultiphaseflow.2026.105634","DOIUrl":"10.1016/j.ijmultiphaseflow.2026.105634","url":null,"abstract":"<div><div>We perform three-dimensional simulations of miscible and immiscible displacements in a cylindrical pipe. For the miscible case, both laminar and turbulent displacement regimes are considered, and our numerical framework uses direct numerical simulation (DNS) and a Large Eddy Simulation (LES) approach based on a Lilly–Smagorinsky model. The dynamics of the flow are governed by the Navier–Stokes equations, coupled with a convective-diffusion equation for the concentration of the more viscous fluid when considering the miscible cases. For the immiscible laminar cases, we perform two-phase DNS considering both pinned and moving contact lines to capture the full range of immiscible dynamic behaviours. The pinned contact line reflects stationary interfaces constrained by surface heterogeneity, while the moving contact line accounts for dynamic interfacial motion influenced by viscous and capillary forces. This study shows that the viscosity contrasts between the two fluids play a significant role in determining the efficiency of ‘cleaning’ of a pipe containing an initially highly viscous resident fluid. When the viscosity of the displaced fluid is low, the laminar displacement flow is efficient in cleaning the pipe; however, when the viscosity increases, the laminar displacement becomes inadequate. Our numerical predictions in the turbulent regime showed that more efficient cleaning is achieved when the viscosity contrast between the two fluids is large. Lastly, our results reveal that the dynamics of a moving contact line can impact both the efficiency and the pattern of cleaning within the pipe.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"197 ","pages":"Article 105634"},"PeriodicalIF":3.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074275","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 : 2026-03-01Epub Date: 2025-12-30DOI: 10.1016/j.ijmultiphaseflow.2025.105591
Guanzhe Cui, Adel Emadzadeh, Zhongyu Xu, Jason Monty, Jimmy Philip
<div><div>To understand the effects of particle settling and Reynolds number, experiments are conducted in a smooth-wall horizontal pipe with a diameter <span><math><mrow><mi>D</mi><mo>=</mo><mn>10</mn><mspace></mspace><mi>cm</mi></mrow></math></span>, and using particles of diameter <span><math><mrow><msub><mrow><mi>d</mi></mrow><mrow><mi>p</mi></mrow></msub><mo>=</mo><mn>250</mn><mspace></mspace><mi>μ</mi><mi>m</mi></mrow></math></span> at viscous-scale Stokes numbers of <span><math><mrow><mi>S</mi><msup><mrow><mi>t</mi></mrow><mrow><mo>+</mo></mrow></msup><mo>=</mo><mn>0</mn><mo>.</mo><mn>96</mn></mrow></math></span>–5.93, a volume fraction of <span><math><mrow><msub><mrow><mi>ϕ</mi></mrow><mrow><mi>v</mi></mrow></msub><mo>=</mo><mn>0</mn><mo>.</mo><mn>022</mn><mtext>%</mtext></mrow></math></span>, and a particle-to-fluid density ratio of <span><math><mrow><msub><mrow><mi>ρ</mi></mrow><mrow><mi>p</mi></mrow></msub><mo>/</mo><msub><mrow><mi>ρ</mi></mrow><mrow><mi>f</mi></mrow></msub><mo>=</mo><mn>1</mn><mo>.</mo><mn>05</mn></mrow></math></span>. Measurements of the streamwise and radial velocities of both the fluid and particle phases are obtained using planar imaging techniques (PIV and PTV). Two friction Reynolds numbers, <span><math><mrow><mi>R</mi><msub><mrow><mi>e</mi></mrow><mrow><mi>τ</mi></mrow></msub><mo>≈</mo><mn>850</mn></mrow></math></span> and <span><math><mrow><mn>2</mn><mspace></mspace><mn>050</mn></mrow></math></span>, corresponding to bulk Reynolds numbers of <span><math><mrow><mi>R</mi><msub><mrow><mi>e</mi></mrow><mrow><mi>b</mi></mrow></msub><mo>=</mo><mn>32</mn><mspace></mspace><mn>000</mn></mrow></math></span> and <span><math><mrow><mn>86</mn><mspace></mspace><mn>000</mn></mrow></math></span>, respectively, are studied, along with an additional experimental dataset at <span><math><mrow><mi>R</mi><msub><mrow><mi>e</mi></mrow><mrow><mi>τ</mi></mrow></msub><mo>≈</mo><mn>190</mn></mrow></math></span> with the same <span><math><mrow><msub><mrow><mi>ρ</mi></mrow><mrow><mi>p</mi></mrow></msub><mo>/</mo><msub><mrow><mi>ρ</mi></mrow><mrow><mi>f</mi></mrow></msub></mrow></math></span>. We observe that turbulence modulation depends on <span><math><mrow><mi>R</mi><msub><mrow><mi>e</mi></mrow><mrow><mi>τ</mi></mrow></msub></mrow></math></span> both at the pipe centreline and off-centreline. In general, the streamwise intensity of the fluid phase increases relative to the unladen case, the radial intensity decreases, and the Reynolds stress is reduced. The velocity statistics of the particle phase generally match those of the fluid phase, except for the radial intensity, which is higher for the particles than for the fluid, highlighting the importance of particle settling. To quantify settling due to gravity, we introduce a new non-dimensional number and use it to classify different experiments in channels and pipes. We also perform a drag decomposition, finding that at the highest <span><math><mrow><mi>R</mi><msub><mrow><mi>e</mi></mro
{"title":"Experimental study of particle-laden turbulent horizontal pipe flows up to Reτ≈ 2000 in the two-way coupling regime","authors":"Guanzhe Cui, Adel Emadzadeh, Zhongyu Xu, Jason Monty, Jimmy Philip","doi":"10.1016/j.ijmultiphaseflow.2025.105591","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105591","url":null,"abstract":"<div><div>To understand the effects of particle settling and Reynolds number, experiments are conducted in a smooth-wall horizontal pipe with a diameter <span><math><mrow><mi>D</mi><mo>=</mo><mn>10</mn><mspace></mspace><mi>cm</mi></mrow></math></span>, and using particles of diameter <span><math><mrow><msub><mrow><mi>d</mi></mrow><mrow><mi>p</mi></mrow></msub><mo>=</mo><mn>250</mn><mspace></mspace><mi>μ</mi><mi>m</mi></mrow></math></span> at viscous-scale Stokes numbers of <span><math><mrow><mi>S</mi><msup><mrow><mi>t</mi></mrow><mrow><mo>+</mo></mrow></msup><mo>=</mo><mn>0</mn><mo>.</mo><mn>96</mn></mrow></math></span>–5.93, a volume fraction of <span><math><mrow><msub><mrow><mi>ϕ</mi></mrow><mrow><mi>v</mi></mrow></msub><mo>=</mo><mn>0</mn><mo>.</mo><mn>022</mn><mtext>%</mtext></mrow></math></span>, and a particle-to-fluid density ratio of <span><math><mrow><msub><mrow><mi>ρ</mi></mrow><mrow><mi>p</mi></mrow></msub><mo>/</mo><msub><mrow><mi>ρ</mi></mrow><mrow><mi>f</mi></mrow></msub><mo>=</mo><mn>1</mn><mo>.</mo><mn>05</mn></mrow></math></span>. Measurements of the streamwise and radial velocities of both the fluid and particle phases are obtained using planar imaging techniques (PIV and PTV). Two friction Reynolds numbers, <span><math><mrow><mi>R</mi><msub><mrow><mi>e</mi></mrow><mrow><mi>τ</mi></mrow></msub><mo>≈</mo><mn>850</mn></mrow></math></span> and <span><math><mrow><mn>2</mn><mspace></mspace><mn>050</mn></mrow></math></span>, corresponding to bulk Reynolds numbers of <span><math><mrow><mi>R</mi><msub><mrow><mi>e</mi></mrow><mrow><mi>b</mi></mrow></msub><mo>=</mo><mn>32</mn><mspace></mspace><mn>000</mn></mrow></math></span> and <span><math><mrow><mn>86</mn><mspace></mspace><mn>000</mn></mrow></math></span>, respectively, are studied, along with an additional experimental dataset at <span><math><mrow><mi>R</mi><msub><mrow><mi>e</mi></mrow><mrow><mi>τ</mi></mrow></msub><mo>≈</mo><mn>190</mn></mrow></math></span> with the same <span><math><mrow><msub><mrow><mi>ρ</mi></mrow><mrow><mi>p</mi></mrow></msub><mo>/</mo><msub><mrow><mi>ρ</mi></mrow><mrow><mi>f</mi></mrow></msub></mrow></math></span>. We observe that turbulence modulation depends on <span><math><mrow><mi>R</mi><msub><mrow><mi>e</mi></mrow><mrow><mi>τ</mi></mrow></msub></mrow></math></span> both at the pipe centreline and off-centreline. In general, the streamwise intensity of the fluid phase increases relative to the unladen case, the radial intensity decreases, and the Reynolds stress is reduced. The velocity statistics of the particle phase generally match those of the fluid phase, except for the radial intensity, which is higher for the particles than for the fluid, highlighting the importance of particle settling. To quantify settling due to gravity, we introduce a new non-dimensional number and use it to classify different experiments in channels and pipes. We also perform a drag decomposition, finding that at the highest <span><math><mrow><mi>R</mi><msub><mrow><mi>e</mi></mro","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"197 ","pages":"Article 105591"},"PeriodicalIF":3.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923474","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 : 2026-03-01Epub Date: 2026-01-31DOI: 10.1016/j.ijmultiphaseflow.2026.105638
Yang Zhang , Shi-Min Li , Shuai Yan , Hao Liang , A-Man Zhang
<div><div>This study employs the compressible two-phase flow model to numerically investigate the buoyancy effect on the dynamics of a single pulsating bubble in bounded fluid domains. The boundaries of the fluid domain consist of two infinite horizontal rigid walls with the height of <span><math><msup><mrow><mi>H</mi></mrow><mrow><mo>∗</mo></mrow></msup></math></span>. The numerical model was validated against an experiment involving a spark-generated bubble between parallel walls, and good agreement in bubble behavior was achieved. The variation of two essential parameters, the buoyancy parameter <span><math><mi>ζ</mi></math></span> and the normalized standoff distance <span><math><msup><mrow><mi>D</mi></mrow><mrow><mo>∗</mo></mrow></msup></math></span> from the lower wall, revealed four distinct jet patterns of the bubble: downward jet, transferred jet, double jet, and upward jet. The transferred jet emerges as increased buoyancy prompts an annular collapse at the base of the bubble, where surrounding fluids converge near the lower wall. When the annular concavity splits the bubble into two sections, the double jet pattern is formed. With the increase in buoyancy, the annular collapse location shifts downward. Eventually, strong buoyancy suppresses annular collapse entirely, leading to a direct upward jet. At a fixed <span><math><msup><mrow><mi>D</mi></mrow><mrow><mo>∗</mo></mrow></msup></math></span>, the wall-center peak pressure reaches a local maximum with increasing <span><math><mi>ζ</mi></math></span> in the transferred and double jet patterns, while conversely showing a declining trend in the upward jet pattern. Specifically, the theoretical condition for vertically neutral collapse of a spherical bubble between parallel walls is derived using the Kelvin impulse theory. By combining this theoretical condition with simulation data, the demarcation between the double jet and upward jet patterns is formulated in two intervals (<span><math><mrow><msup><mrow><mi>D</mi></mrow><mrow><mo>∗</mo></mrow></msup><mi>ζ</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>38</mn><msup><mrow><mfenced><mrow><mn>1</mn><mo>−</mo><mfenced><mrow><msup><mrow><mi>D</mi></mrow><mrow><mo>∗</mo></mrow></msup><mo>/</mo><mfenced><mrow><msup><mrow><mi>H</mi></mrow><mrow><mo>∗</mo></mrow></msup><mo>−</mo><msup><mrow><mi>D</mi></mrow><mrow><mo>∗</mo></mrow></msup></mrow></mfenced></mrow></mfenced></mrow></mfenced></mrow><mrow><mn>0</mn><mo>.</mo><mn>49</mn></mrow></msup><mo>,</mo><msup><mrow><mi>D</mi></mrow><mrow><mo>∗</mo></mrow></msup><mo><</mo><msup><mrow><mi>H</mi></mrow><mrow><mo>∗</mo></mrow></msup><mo>/</mo><mn>2</mn></mrow></math></span> and <span><math><mrow><msup><mrow><mi>D</mi></mrow><mrow><mo>∗</mo></mrow></msup><mi>ζ</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>22</mn><msup><mrow><mfenced><mrow><mn>1</mn><mo>−</mo><msup><mrow><mfenced><mrow><msup><mrow><mi>D</mi></mrow><mrow><mo>∗</mo></mrow></msup><mo>/</mo><mfenced><mrow><msup><mrow><mi>H</mi></mrow><mrow><mo>∗</mo></m
{"title":"Buoyancy effect on the bubble dynamics in bounded fluid domains","authors":"Yang Zhang , Shi-Min Li , Shuai Yan , Hao Liang , A-Man Zhang","doi":"10.1016/j.ijmultiphaseflow.2026.105638","DOIUrl":"10.1016/j.ijmultiphaseflow.2026.105638","url":null,"abstract":"<div><div>This study employs the compressible two-phase flow model to numerically investigate the buoyancy effect on the dynamics of a single pulsating bubble in bounded fluid domains. The boundaries of the fluid domain consist of two infinite horizontal rigid walls with the height of <span><math><msup><mrow><mi>H</mi></mrow><mrow><mo>∗</mo></mrow></msup></math></span>. The numerical model was validated against an experiment involving a spark-generated bubble between parallel walls, and good agreement in bubble behavior was achieved. The variation of two essential parameters, the buoyancy parameter <span><math><mi>ζ</mi></math></span> and the normalized standoff distance <span><math><msup><mrow><mi>D</mi></mrow><mrow><mo>∗</mo></mrow></msup></math></span> from the lower wall, revealed four distinct jet patterns of the bubble: downward jet, transferred jet, double jet, and upward jet. The transferred jet emerges as increased buoyancy prompts an annular collapse at the base of the bubble, where surrounding fluids converge near the lower wall. When the annular concavity splits the bubble into two sections, the double jet pattern is formed. With the increase in buoyancy, the annular collapse location shifts downward. Eventually, strong buoyancy suppresses annular collapse entirely, leading to a direct upward jet. At a fixed <span><math><msup><mrow><mi>D</mi></mrow><mrow><mo>∗</mo></mrow></msup></math></span>, the wall-center peak pressure reaches a local maximum with increasing <span><math><mi>ζ</mi></math></span> in the transferred and double jet patterns, while conversely showing a declining trend in the upward jet pattern. Specifically, the theoretical condition for vertically neutral collapse of a spherical bubble between parallel walls is derived using the Kelvin impulse theory. By combining this theoretical condition with simulation data, the demarcation between the double jet and upward jet patterns is formulated in two intervals (<span><math><mrow><msup><mrow><mi>D</mi></mrow><mrow><mo>∗</mo></mrow></msup><mi>ζ</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>38</mn><msup><mrow><mfenced><mrow><mn>1</mn><mo>−</mo><mfenced><mrow><msup><mrow><mi>D</mi></mrow><mrow><mo>∗</mo></mrow></msup><mo>/</mo><mfenced><mrow><msup><mrow><mi>H</mi></mrow><mrow><mo>∗</mo></mrow></msup><mo>−</mo><msup><mrow><mi>D</mi></mrow><mrow><mo>∗</mo></mrow></msup></mrow></mfenced></mrow></mfenced></mrow></mfenced></mrow><mrow><mn>0</mn><mo>.</mo><mn>49</mn></mrow></msup><mo>,</mo><msup><mrow><mi>D</mi></mrow><mrow><mo>∗</mo></mrow></msup><mo><</mo><msup><mrow><mi>H</mi></mrow><mrow><mo>∗</mo></mrow></msup><mo>/</mo><mn>2</mn></mrow></math></span> and <span><math><mrow><msup><mrow><mi>D</mi></mrow><mrow><mo>∗</mo></mrow></msup><mi>ζ</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>22</mn><msup><mrow><mfenced><mrow><mn>1</mn><mo>−</mo><msup><mrow><mfenced><mrow><msup><mrow><mi>D</mi></mrow><mrow><mo>∗</mo></mrow></msup><mo>/</mo><mfenced><mrow><msup><mrow><mi>H</mi></mrow><mrow><mo>∗</mo></m","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"197 ","pages":"Article 105638"},"PeriodicalIF":3.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146170400","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 : 2026-03-01Epub Date: 2026-01-19DOI: 10.1016/j.ijmultiphaseflow.2026.105624
Andrea Düll , Alexander Nies , Álvaro Echeverría de Encio , Lyes Kahouadji , Seungwon Shin , Jalel Chergui , Damir Juric , Olaf Deutschmann , Omar K. Matar
Wave evolution in thin-film flows is highly relevant for heat and mass transfer applications, such as CO2 capture in falling film absorbers. To develop a detailed understanding of potential enhancement mechanisms associated with the evolution of three-dimensional (3D) waveforms, we perform 3D direct numerical simulations of passive scalar transport in laminar-wavy film flows, using a hybrid front-tracking/level-set method to accurately resolve interfacial features. CO2 absorption is greatly enhanced in the presence of interfacial waves with the liquid-side mass transfer coefficient increasing tenfold relative to that of a flat film for the highest film Reynolds numbers () studied. This is primarily due to changes in interfacial and internal flow dynamics rather than an increase in the gas-liquid interfacial area. The recirculation region present in the leading and trailing fronts of the 3D waves intensifies mass transfer, and their effectiveness increases with . At low , there is a film region beneath the wavy interface, which remains relatively undisturbed where mass transfer is dominated by diffusion. The introduction of structured substrates to promote mass transfer under these conditions is recommended. The visco-capillary ripple region, which precedes the leading and trailing fronts for sufficiently high , provides a relatively high degree of spanwise advection, with the mean spanwise velocity magnitude reaching around one-quarter that in the streamwise direction. This underscores the importance of solving the fully-3D problem as these effects do not have a two-dimensional analogue.
{"title":"Three-dimensional effects on carbon capture in wavy falling films","authors":"Andrea Düll , Alexander Nies , Álvaro Echeverría de Encio , Lyes Kahouadji , Seungwon Shin , Jalel Chergui , Damir Juric , Olaf Deutschmann , Omar K. Matar","doi":"10.1016/j.ijmultiphaseflow.2026.105624","DOIUrl":"10.1016/j.ijmultiphaseflow.2026.105624","url":null,"abstract":"<div><div>Wave evolution in thin-film flows is highly relevant for heat and mass transfer applications, such as CO<sub>2</sub> capture in falling film absorbers. To develop a detailed understanding of potential enhancement mechanisms associated with the evolution of three-dimensional (3D) waveforms, we perform 3D direct numerical simulations of passive scalar transport in laminar-wavy film flows, using a hybrid front-tracking/level-set method to accurately resolve interfacial features. CO<sub>2</sub> absorption is greatly enhanced in the presence of interfacial waves with the liquid-side mass transfer coefficient increasing tenfold relative to that of a flat film for the highest film Reynolds numbers (<span><math><mrow><mi>R</mi><mi>e</mi></mrow></math></span>) studied. This is primarily due to changes in interfacial and internal flow dynamics rather than an increase in the gas-liquid interfacial area. The recirculation region present in the leading and trailing fronts of the 3D waves intensifies mass transfer, and their effectiveness increases with <span><math><mrow><mi>R</mi><mi>e</mi></mrow></math></span>. At low <span><math><mrow><mi>R</mi><mi>e</mi></mrow></math></span>, there is a film region beneath the wavy interface, which remains relatively undisturbed where mass transfer is dominated by diffusion. The introduction of structured substrates to promote mass transfer under these conditions is recommended. The visco-capillary ripple region, which precedes the leading and trailing fronts for sufficiently high <span><math><mrow><mi>R</mi><mi>e</mi></mrow></math></span>, provides a relatively high degree of spanwise advection, with the mean spanwise velocity magnitude reaching around one-quarter that in the streamwise direction. This underscores the importance of solving the fully-3D problem as these effects do not have a two-dimensional analogue.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"197 ","pages":"Article 105624"},"PeriodicalIF":3.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146023322","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 : 2026-03-01Epub Date: 2026-01-29DOI: 10.1016/j.ijmultiphaseflow.2026.105635
Mariana Costa , Tom van Terwisga , Daniele Fiscaletti , Jerry Westerweel
In tribonucleation, a liquid-to-gas phase transition induced by a local pressure drop (cavitation) is highly undesirable, as it causes surface erosion and noise. A paradigmatic flow characteristic of tribonucleation problems is the flow between two coaxial disks. The flow is produced by the rapid upward movement of the top disk, which is initially at rest and in contact with the bottom disk. An analytical model, the so-called negative squeeze film, is typically used to predict the flow in the gap between the disks in this class of problems. Such a model considers an azimuthally uniform inflow in the gap between the disks. In this study, we experimentally show that if a negligibly small misalignment between the axes of the two disks is introduced, the inflow is not azimuthally uniform as expected from the negative squeeze film, but an entry jet appears in the flow between the disks. This entry jet is associated with the formation of two counter-rotating vortices. From reconstructing the pressure field from PIV velocity data in the vortex regions, we find that the local pressure is lower than the vapor pressure. This indicates that the gaseous phase in the cores of the vortices, which is observed from shadowgraphy visualizations in our study, should be attributed to cavitation. The negative-squeeze-film model, however, largely fails to predict the minimum pressure. Therefore, the onset of cavitation is not correctly captured by the analytical model.
{"title":"Cavitation onset in counter-rotating vortices from separating disks","authors":"Mariana Costa , Tom van Terwisga , Daniele Fiscaletti , Jerry Westerweel","doi":"10.1016/j.ijmultiphaseflow.2026.105635","DOIUrl":"10.1016/j.ijmultiphaseflow.2026.105635","url":null,"abstract":"<div><div>In tribonucleation, a liquid-to-gas phase transition induced by a local pressure drop (cavitation) is highly undesirable, as it causes surface erosion and noise. A paradigmatic flow characteristic of tribonucleation problems is the flow between two coaxial disks. The flow is produced by the rapid upward movement of the top disk, which is initially at rest and in contact with the bottom disk. An analytical model, the so-called negative squeeze film, is typically used to predict the flow in the gap between the disks in this class of problems. Such a model considers an azimuthally uniform inflow in the gap between the disks. In this study, we experimentally show that if a negligibly small misalignment between the axes of the two disks is introduced, the inflow is not azimuthally uniform as expected from the negative squeeze film, but an entry jet appears in the flow between the disks. This entry jet is associated with the formation of two counter-rotating vortices. From reconstructing the pressure field from PIV velocity data in the vortex regions, we find that the local pressure is lower than the vapor pressure. This indicates that the gaseous phase in the cores of the vortices, which is observed from shadowgraphy visualizations in our study, should be attributed to cavitation. The negative-squeeze-film model, however, largely fails to predict the minimum pressure. Therefore, the onset of cavitation is not correctly captured by the analytical model.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"197 ","pages":"Article 105635"},"PeriodicalIF":3.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074278","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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