International Journal of Multiphase Flow最新文献

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Hagen–Poiseuille flow in the pipe layered by porous medium is linearly unstable 多孔介质层状管道中的Hagen-Poiseuille流动是线性不稳定的
IF 3.6 2区 工程技术
International Journal of Multiphase Flow Pub Date : 2025-04-16 DOI: 10.1016/j.ijmultiphaseflow.2025.105243
Ajay Sharma , P. Bera , Gaurav Sharma
{"title":"Hagen–Poiseuille flow in the pipe layered by porous medium is linearly unstable","authors":"Ajay Sharma , P. Bera , Gaurav Sharma","doi":"10.1016/j.ijmultiphaseflow.2025.105243","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105243","url":null,"abstract":"<div><div>The long-standing linearly stable Hagen–Poiseuille flow is shown to become unstable when a low-permeable porous medium layers the inner surface of the pipe. The analysis indicates that depending upon the media permeability, a threshold value of the fluid layer thickness exists below which the onset of instability occurs under axisymmetric disturbances, whereas above the threshold value, the same occurs under non-axisymmetric disturbance. In the former case, the instability is induced due to the interaction of the dynamics of base flow with the porous layer and leads to the porous mode of instability. The latter case is due to the combined effect of Reynolds stress in the fluid regime and slip porous boundary at the interface, and gives rise to the fluid mode of instability. For instance, when the Darcy number (<span><math><mrow><mi>D</mi><mi>a</mi></mrow></math></span>) and Beavers-Joseph slip coefficient (<span><math><msub><mrow><mi>α</mi></mrow><mrow><msub><mrow></mrow><mrow><msub><mrow></mrow><mrow><mi>B</mi><mi>J</mi></mrow></msub></mrow></msub></mrow></msub></math></span>) are fixed at <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>6</mn></mrow></msup></mrow></math></span> and 0.1, respectively, the threshold value of thickness ratio, <span><math><mover><mrow><mi>t</mi></mrow><mrow><mo>ˆ</mo></mrow></mover></math></span> is around 0.0336. Our results show that the threshold value of <span><math><mover><mrow><mi>t</mi></mrow><mrow><mo>ˆ</mo></mrow></mover></math></span> increases monotonically with an increase in <span><math><mrow><mi>D</mi><mi>a</mi></mrow></math></span>. In the fluid mode, energy production due to Reynolds stress is balanced by energy loss via viscous dissipation, whereas in porous mode, the same is balanced mainly by combined energy loss via surface drag and work done at the interface. In addition, keeping the thickness of the porous region fixed, the fluid layer thickness for which almost similar instability characteristics are found varies directly as the square root of media permeability. Our rigorous analysis also shows that <span><math><msub><mrow><mi>α</mi></mrow><mrow><msub><mrow></mrow><mrow><msub><mrow></mrow><mrow><mi>B</mi><mi>J</mi></mrow></msub></mrow></msub></mrow></msub></math></span> destabilizes the flow, and the onset of instability takes place at Reynolds number as small as 695, when <span><math><mrow><mi>D</mi><mi>a</mi><mo>=</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>6</mn></mrow></msup><mo>,</mo><msub><mrow><mi>α</mi></mrow><mrow><msub><mrow></mrow><mrow><msub><mrow></mrow><mrow><mi>B</mi><mi>J</mi></mrow></msub></mrow></msub></mrow></msub><mo>=</mo><mn>0</mn><mo>.</mo><mn>3</mn></mrow></math></span> and <span><math><mrow><mover><mrow><mi>t</mi></mrow><mrow><mo>ˆ</mo></mrow></mover><mo>=</mo><mn>0</mn><mo>.</mo><mn>016</mn></mrow></math></span>. Furthermore, an increase in <span><math><msub><mrow><mi>α</mi></mrow><mrow><msub><mrow></mrow><mro","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"189 ","pages":"Article 105243"},"PeriodicalIF":3.6,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143864674","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}
引用次数: 0
Transition of flow between eccentrically rotating double cylinders 偏心旋转双气缸间的流动过渡
IF 3.6 2区 工程技术
International Journal of Multiphase Flow Pub Date : 2025-04-16 DOI: 10.1016/j.ijmultiphaseflow.2025.105236
Tomoaki Watamura , Kazuyasu Sugiyama , Shu Takagi
{"title":"Transition of flow between eccentrically rotating double cylinders","authors":"Tomoaki Watamura ,&nbsp;Kazuyasu Sugiyama ,&nbsp;Shu Takagi","doi":"10.1016/j.ijmultiphaseflow.2025.105236","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105236","url":null,"abstract":"<div><div>We report on the drag force acting on a mixing rod which rotates at the same rate as its orbital motion in a circular container. To gain insights into the mechanism of the drag increase owing to the wake development, we perform a series of numerical simulations in which the Reynolds number, the radius of a rod, and its orbit are parameterized. The flow transition can be realized by increasing the Reynolds number but strongly depends on the system geometries. To account for this transition, the gap Reynolds number is introduced herein; we find that the drag increase and the onset of vortex shedding can be well-scaled by the gap Reynolds number. We further demonstrate that the number of azimuthal waves is relevant to the eccentricity. The current findings, albeit empirical, suggest that the sidewall confinement can efficiently lead to a delay of flow transition and open a new venue for controlling the fluid–structure interaction in mixing processes.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"189 ","pages":"Article 105236"},"PeriodicalIF":3.6,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143843190","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}
引用次数: 0
Validation and calibration of a millimeter-wave interferometer for concentration measurements in particle-laden flows 用于颗粒流浓度测量的毫米波干涉仪的验证和校准
IF 3.6 2区 工程技术
International Journal of Multiphase Flow Pub Date : 2025-04-15 DOI: 10.1016/j.ijmultiphaseflow.2025.105234
Nicolas Rasmont, Joshua Rovey , Laura Villafañe
{"title":"Validation and calibration of a millimeter-wave interferometer for concentration measurements in particle-laden flows","authors":"Nicolas Rasmont,&nbsp;Joshua Rovey ,&nbsp;Laura Villafañe","doi":"10.1016/j.ijmultiphaseflow.2025.105234","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105234","url":null,"abstract":"<div><div>Millimeter-wave interferometry is a novel method for measuring absolute concentrations in opaque dispersed multiphase flows. Its advantages include: the ability to penetrate dense particles clouds with minimal transmission loss compared to optical radiation (i.e., near-visible light), a linear response to volume fraction that is mostly independent of particle properties, the use of safe non-ionizing radiation, kilohertz sampling rates, and compact low-cost hardware. Spatial resolution is the main limiting factor of the technique when sub-wavelength resolution is required. In this work, we compare two methods to calibrate a millimeter-wave radar interferometer for absolute concentration measurements: a direct method that uses known particle concentrations, and an indirect method that relies on measuring the relative permittivity of bulk particle samples. Direct calibration results derived from earlier work by the authors are improved through the use of high-resolution X-ray micro-tomography to measure the particle size distribution and overlap-tolerant particle counting algorithms. The indirect calibration method utilizes a custom interference-based technique to measure the relative permittivity of a bulk powder at millimeter-wave frequencies. Results from both calibration methods agree within 0.7% when using the Lichtenecker logarithmic effective medium equation. The agreement between the two independent calibration procedures validates the theoretical framework of millimeter-wave interferometry.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"189 ","pages":"Article 105234"},"PeriodicalIF":3.6,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143848456","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}
引用次数: 0
Numerical Simulations of bubbly turbulent convection in cubical geometries 立方体几何气泡湍流对流的数值模拟
IF 3.6 2区 工程技术
International Journal of Multiphase Flow Pub Date : 2025-04-15 DOI: 10.1016/j.ijmultiphaseflow.2025.105244
Joauma Marichal , Yann Bartosiewicz , Pierre Ruyer
{"title":"Numerical Simulations of bubbly turbulent convection in cubical geometries","authors":"Joauma Marichal ,&nbsp;Yann Bartosiewicz ,&nbsp;Pierre Ruyer","doi":"10.1016/j.ijmultiphaseflow.2025.105244","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105244","url":null,"abstract":"<div><div>In this work we present numerical results of bubble dynamics in a turbulent Rayleigh–Bénard convection configuration, using our in-house code in a cubical geometry. The problem in hand is encountered in various natural phenomena as well as in industrial applications. A Eulerian–Lagrangian approach is developed for the mixture of liquid water and vapor bubbles. The liquid mean temperature is close to the saturation temperature and is governed by the quasi-incompressible Navier–Stokes equations that are solved using Direct Numerical Simulations (DNS) standards. The motion and growth/shrinkage of each individual vapor bubble is modeled and the effect of the bubbles on the fluid is accounted via momentum and energy exchanges between the two phases (two-way coupling).</div><div>At first, we describe the model used and its corresponding validation, involving isolated bubble dynamics and coupling between bubbly and bulk flows. In the second part, we consider the study of the flow topology, the bubble related statistics, the heat transfer (Nusselt number) and the turbulence statistics for different settings of the bubbly configurations.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"189 ","pages":"Article 105244"},"PeriodicalIF":3.6,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143868769","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}
引用次数: 0
A-posteriori assessment of mixed models for Large Eddy Simulation of polydisperse multiphase flows 多分散多相流大涡模拟混合模型的后验评价
IF 3.6 2区 工程技术
International Journal of Multiphase Flow Pub Date : 2025-04-12 DOI: 10.1016/j.ijmultiphaseflow.2025.105231
Andreas Iberl, Elias Trautner, Markus Klein, Josef Hasslberger
{"title":"A-posteriori assessment of mixed models for Large Eddy Simulation of polydisperse multiphase flows","authors":"Andreas Iberl,&nbsp;Elias Trautner,&nbsp;Markus Klein,&nbsp;Josef Hasslberger","doi":"10.1016/j.ijmultiphaseflow.2025.105231","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105231","url":null,"abstract":"<div><div>This study presents a detailed analysis of various turbulence modeling approaches for the convective subgrid-scale term in the context of Large Eddy Simulation (LES) of a polydisperse two-phase flow. The numerical framework is based on the Volume-of-Fluid (VOF) method. The presented a-posteriori investigation assesses the potential for mixed modeling combining the well-known eddy viscosity model of Smagorinsky and the scale similarity type model of Liu in two different ways. The first approach employs a dynamic blending function based on a subgrid activity sensor, whereas the second approach is based on an explicit scale separation. A preceding analysis of the laminar-turbulent transition for the Taylor-Green vortex reveals that, compared to the standalone formulation of the models, a combination of a functional and a structural model results in a more accurate prediction of the turbulent kinetic energy and its dissipation rate. The main focus of this work is on the simulation of a gas injection into a liquid-filled domain. This study presents a first investigation of advanced mixed LES models for polydisperse bubble-laden flows characterized by a realistic water-to-air density ratio. The distributions of the gas volume fraction and the gas phase velocity obtained in the LES cases employing the mixed models show a good agreement with reference data from both numerical and experimental investigations. These findings indicate that mixed type turbulence modeling is a promising candidate for an efficient and accurate prediction of industry-scale multiphase flows.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"189 ","pages":"Article 105231"},"PeriodicalIF":3.6,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143843189","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}
引用次数: 0
Development of the AI-assisted thermal hydraulic analysis method for condensing bubbles in vertical subcooled flow boiling 垂直过冷流沸腾冷凝气泡人工智能辅助热水力分析方法的发展
IF 3.6 2区 工程技术
International Journal of Multiphase Flow Pub Date : 2025-04-12 DOI: 10.1016/j.ijmultiphaseflow.2025.105246
Wen Zhou , Shuichiro Miwa , Ryoma Tsujimura , Thanh-Binh Nguyen , Tomio Okawa , Koji Okamoto
{"title":"Development of the AI-assisted thermal hydraulic analysis method for condensing bubbles in vertical subcooled flow boiling","authors":"Wen Zhou ,&nbsp;Shuichiro Miwa ,&nbsp;Ryoma Tsujimura ,&nbsp;Thanh-Binh Nguyen ,&nbsp;Tomio Okawa ,&nbsp;Koji Okamoto","doi":"10.1016/j.ijmultiphaseflow.2025.105246","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105246","url":null,"abstract":"<div><div>Subcooled flow boiling is critical in various industrial applications such as nuclear reactors and thermal management systems. The rapid and complex dynamics of condensing bubbles, from their inception to collapse, pose significant challenges for conventional bubble detection methods. In light of this, a state-of-the-art AI method is developed and validated for the detection and tracking of condensing bubbles in subcooled flow boiling, thereby enabling the effective execution of thermal hydraulic analyses. This study initially employs computer vision technology to efficiently construct a bubble dataset. A bubble detection model, utilizing YOLOv8 with an attention mechanism, is then trained on this dataset. Following successful bubble detection, a multi-object tracking algorithm tracks the bubbles across successive frames. The developed AI-based method has proven highly effective, detecting 95 % of condensation bubbles and streamlining the extraction of key thermal hydraulic parameters, including aspect ratio, Sauter mean diameter, void fraction, interfacial area concentration, departure diameter, growth time, bubble lifetime, Nusselt number, and nucleation site density. The model's accuracy and consistency are demonstrated compared to empirical correlations, affirming its reliability in analyzing the intricate dynamics of subcooled flow boiling. Additionally, it provides detailed fluctuation data on thermal hydraulic parameters. This AI-based method not only improves the reliability and efficiency of monitoring and analyzing subcooled flow boiling but also exemplifies the transformative potential of AI in refining complex industrial processes.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"189 ","pages":"Article 105246"},"PeriodicalIF":3.6,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143864673","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}
引用次数: 0
Experimental study of bubble clouds generated by multi-plunging jets 多突射流产生气泡云的实验研究
IF 3.6 2区 工程技术
International Journal of Multiphase Flow Pub Date : 2025-04-12 DOI: 10.1016/j.ijmultiphaseflow.2025.105238
Narendra Dev, Hélène Scolan, J. John Soundar Jerome, Jean-Philippe Matas
{"title":"Experimental study of bubble clouds generated by multi-plunging jets","authors":"Narendra Dev,&nbsp;Hélène Scolan,&nbsp;J. John Soundar Jerome,&nbsp;Jean-Philippe Matas","doi":"10.1016/j.ijmultiphaseflow.2025.105238","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105238","url":null,"abstract":"<div><div>Industrial and natural processes frequently involve plunging jets that break into clusters of liquid columns or droplets, impacting the liquid surface. To simulate air entrainment by fragmented plunging jets, we first examine bubble clouds formed by twin and triple identical jets. Bubble clouds from individual jets merge after a certain pre-interaction depth and become a unified cloud, similar to the case of a single plunging jet. We then perform experiments with hexagonally packed multiple identical jets to mimic large fragmented jets. They generate a single bubble cloud without revealing a pre-interaction depth. Doppler optical probe measurements reveal that the radial profiles of air/water fraction, <span><math><mi>ϕ</mi></math></span>, are initially bimodal just after the jet impact, gradually transitioning into a single Gaussian distribution at further depth. For a given impact velocity <span><math><msub><mrow><mi>V</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span>, an increase in the number of jets results in a slower decay of the mean bubble speed at the cloud axis. Furthermore, the net air flux does not scale with the number of jets but is proportional to the diameter of the multi-jet. In all cases, the mean bubble size in a bubble cloud increases with depth, which may be primarily driven by the coalescence of bubbles as suggested by high-speed images and Weber number analysis. The mean penetration depth of bubbles, <span><math><mi>H</mi></math></span>, increases with the number of jets. Our investigations indicate that the momentum flux balance in the presence of buoyancy can be successfully used to estimate bubble cloud depth and the centreline velocity in all multi-jet experiments.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"189 ","pages":"Article 105238"},"PeriodicalIF":3.6,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143839433","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}
引用次数: 0
Gradients-based measurements to understand the boiling characteristics of dichloromethane for thermal management applications 基于梯度的测量,以了解热管理应用中二氯甲烷的沸腾特性
IF 3.6 2区 工程技术
International Journal of Multiphase Flow Pub Date : 2025-04-12 DOI: 10.1016/j.ijmultiphaseflow.2025.105258
Alok Kumar , Mohammad Autif Shahdhaar , Jaywant H. Arakeri , Atul Srivastava
{"title":"Gradients-based measurements to understand the boiling characteristics of dichloromethane for thermal management applications","authors":"Alok Kumar ,&nbsp;Mohammad Autif Shahdhaar ,&nbsp;Jaywant H. Arakeri ,&nbsp;Atul Srivastava","doi":"10.1016/j.ijmultiphaseflow.2025.105258","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105258","url":null,"abstract":"<div><div>The present work investigates the dynamical characteristics of single vapor bubble during saturated nucleate boiling of dichloromethane (DCM), one of the high volatile fluids. Boiling experiments have been performed for four heat flux conditions (25, 35, 50, and 65 kW/m²) under atmospheric pressure. Thin-film interferometry and high-speed rainbow schlieren deflectometry were employed in tandem to simultaneously capture the dynamics of microlayer and/or dry-patch and vapor bubbles. A detailed analysis of the temporal evolution of the equivalent diameter of DCM bubbles reveals distinct phases: inertia-controlled growth, a transitional regime, and diffusion-controlled expansion. Furthermore, the temporal evolution of various forces, such as buoyancy, contact pressure, surface tension, and growth forces are examined during the ebullition cycle. Unlike traditional force balance analyses, the spatio-temporally resolved whole-field experimental data is used for delineating the forces involved from bubble inception to departure time (<em>t<sub>d</sub></em>). Notably, in contrast to the conventional working fluids, for instance water, DCM displays a distinct bubble formation mechanism that is devoid of any microlayer, despite its high wettability with indium-tin-oxide coated glass. As the heat flux increases, there is a corresponding linear increase in bubble departure frequency, with no significant rise in growth time. The force balance analysis during the ebullition cycle of the vapor bubble of the considered high volatile fluid reveals that until 0.8<em>t<sub>d</sub></em>, the prevailing downward force promotes bubble growth while inhibiting departure. However, beyond 0.8<em>t<sub>d</sub></em>, the upward force takes precedence, counteracting the downward force and enables the bubble's departure from the nucleating surface.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"189 ","pages":"Article 105258"},"PeriodicalIF":3.6,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143850599","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}
引用次数: 0
Vapor condensation heat transfer on mixed-wettability surface with lattice Boltzmann model 基于晶格玻尔兹曼模型的混合润湿性表面的蒸汽冷凝传热
IF 3.6 2区 工程技术
International Journal of Multiphase Flow Pub Date : 2025-04-12 DOI: 10.1016/j.ijmultiphaseflow.2025.105259
Tong Zheng, Ruoxi Li, Xiangwei Yin, Shengqiang Shen, Gangtao Liang
{"title":"Vapor condensation heat transfer on mixed-wettability surface with lattice Boltzmann model","authors":"Tong Zheng,&nbsp;Ruoxi Li,&nbsp;Xiangwei Yin,&nbsp;Shengqiang Shen,&nbsp;Gangtao Liang","doi":"10.1016/j.ijmultiphaseflow.2025.105259","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105259","url":null,"abstract":"<div><div>Based on an improved three-dimensional phase-change lattice Boltzmann method (LBM), this study conducts three-dimensional numerical simulations for vapor condensation heat transfer on the mixed wettability surface consisting of a hydrophobic substrate decorated by the hydrophilic regions. Droplet nucleation, growth and detachment from such surface are discussed in detail, with regarding the parametric effects of the shape, size and spacing of the hydrophilic regions, as well as contact angles of both the hydrophilic and hydrophobic regions. Results show that the hydrophilic regions with identical area but different shapes lead to minor differences in heat transfer performance. However, the regions with equal perimeter but various shapes can result in significant differences. The size of the hydrophilic region is a key factor affecting droplet nucleation, and a larger hydrophilic region can increase the surface heat flux and enable earlier droplet detachment. Besides, a smaller spacing between hydrophilic regions promotes droplet formation, despite the fact that an excessively small spacing inhibits droplet detachment. The contact angles of both hydrophilic and hydrophobic regions can affect droplet formation, with the former influencing early-stage formation and the latter impacting later-stage growth. This study further improves the understanding of the mixed wettability surfaces used in the vapor condensation scenario from the numerical view.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"189 ","pages":"Article 105259"},"PeriodicalIF":3.6,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143843266","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}
引用次数: 0
Investigation of the fouling layer growth using coupled immersed boundary and Eulerian-Lagrangian methods 使用沉浸边界和欧拉-拉格朗日耦合方法研究污垢层的生长情况
IF 3.6 2区 工程技术
International Journal of Multiphase Flow Pub Date : 2025-04-11 DOI: 10.1016/j.ijmultiphaseflow.2025.105241
Sajad Khodadadi , Reza Maddahian
{"title":"Investigation of the fouling layer growth using coupled immersed boundary and Eulerian-Lagrangian methods","authors":"Sajad Khodadadi ,&nbsp;Reza Maddahian","doi":"10.1016/j.ijmultiphaseflow.2025.105241","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105241","url":null,"abstract":"<div><div>This study presents a numerical simulation of fouling, focusing on the complex, unsteady, multiphase, and turbulent process of fouling layer growth on the outer surface of a heat exchanger's pipe. Addressing the fundamental challenges associated with fouling phenomenon, an Eulerian-Lagrangian approach is employed, wherein the Eulerian method calculates continuous phase flow parameters, such as velocity and pressure, and the Lagrangian method precisely tracks particles near the surface. The immersed boundary method is utilized to simulate fouling layer growth without altering the underlying grid, effectively reducing computational cost compared to dynamic mesh methods. The model is validated against experimental data involving ash particle deposition on a cylindrical surface. Key parameters, including Young's modulus, Reynolds number, and particle size distribution, are systematically analyzed. The findings reveal that particles smaller than 10 micrometers can penetrate the rear of the cylinder, while larger particles (25-30 micrometers) predominantly accumulate on the front, exhibiting nearly double the deposition frequency compared to smaller particles. As particle diameter increases, both Young's modulus and flow velocity contribute to a reduced settling rate by lowering the critical deposition velocity. A higher Reynolds number results in a 67 % reduction in fouling mass due to decreased adhesive velocity and enhanced particle detachment. Additionally, larger particles tend to migrate towards the edges of the heat exchanger tube, promoting a more uniform surface distribution. Notably, at elevated Young's modulus values (e.g., 50,000 MPa), particle deposition on the surface is virtually eliminated.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"189 ","pages":"Article 105241"},"PeriodicalIF":3.6,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143855968","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}
引用次数: 0
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