International Journal of Multiphase Flow最新文献

{"title":"Dynamics of jet formation in inertial droplet","authors":"Arahata Senapati ,&nbsp;Gaurav Singh ,&nbsp;Arnab Atta ,&nbsp;Rajaram Lakkaraju","doi":"10.1016/j.ijmultiphaseflow.2025.105242","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105242","url":null,"abstract":"<div><div>We present a numerical investigation of a suddenly accelerated droplet in a surrounding viscous liquid, which exposes the droplet to inertial forces until it eventually comes to a stop. Using the volume of fluid method, we observed that as the droplet moves, it generates a toroidal vortex, and a high-speed liquid jet develops at its rear, with speeds exceeding the droplet’s speed by at least an order of magnitude. Our study focused on droplet deformation and liquid jet characteristics across a range of Weber numbers (<span><math><mrow><mi>W</mi><mi>e</mi></mrow></math></span>) from 13 to 200 and Ohnesorge numbers (<span><math><mrow><mi>O</mi><mi>h</mi></mrow></math></span>) from <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>4</mn></mrow></msup></mrow></math></span> to <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></mrow></math></span>. Based on the characteristics of the jets, we classified them into three categories: (1) weak jets that cannot penetrate the rear side of the droplet for <span><math><mrow><mn>13</mn><mo>&lt;</mo><mi>W</mi><mi>e</mi><mo>&lt;</mo><mn>23</mn></mrow></math></span>, (2) short jets that can penetrate the droplet for <span><math><mrow><mn>23</mn><mo>&lt;</mo><mi>W</mi><mi>e</mi><mo>&lt;</mo><mn>50</mn></mrow></math></span>, and (3) strong jets that rupture the droplet for <span><math><mrow><mi>W</mi><mi>e</mi><mo>&gt;</mo><mn>50</mn></mrow></math></span>. Our results indicate that droplet deformation is independent of the Ohnesorge number (<span><math><mrow><mi>O</mi><mi>h</mi></mrow></math></span>). We developed a semi-analytical theory based on the energy analysis to predict the maximum jet speed.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"189 ","pages":"Article 105242"},"PeriodicalIF":3.6,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143890659","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}

{"title":"Plateau–Rayleigh instability in low-viscosity ratio stratified liquid–liquid flow","authors":"P.J. Miranda-Lugo,&nbsp;O.M.H. Rodriguez","doi":"10.1016/j.ijmultiphaseflow.2025.105253","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105253","url":null,"abstract":"<div><div>Stratified liquid–liquid flow is still an open research subject due to the complex interfacial interactions and its hydrodynamic stability in specific operational conditions. The literature contains different theories explaining the stratified flow transition. A recent theory suggests that the interface’s cross-section curvature is related to capillary instability, which effect is stronger at high water volumetric fractions. At such conditions, interfacial tension contributes to forming a concave interface at the flow’s cross-section. Nevertheless, as far as the authors are concerned, no experimental study has quantified the magnitude of the destabilizing interfacial-tension term related to the interface’s cross-section curvature, which can lead stratified flow to transition to plug flow. We measure such an effect in a horizontal stratified oil–water pipe flow with low Eötvös number using Planar Laser-Induced Fluorescence (PLIF) and shadow sizing techniques in a novel experimental facility. Mineral oil and tap water with a low-viscosity ratio of 1.44 were used. Geometrical and kinematic properties of the interfacial wave at the flow’s longitudinal diametrical vertical and cross-section planes for stable and unstable flow conditions were determined by a homemade scanning algorithm that identifies the oil–water interface. The interface’s cross-section curvature of stratified pipe flow was measured for the first time. A novel expression was proposed to correlate the interface’s cross-section curvature with the mean water height, which is associated with the interfacial tension force that has a dominant effect on transition. A linear stability analysis based on the 1-D two-fluid model was carried out and suggested that capillary instability can be strong enough to promote the transition from stratified to plug flow at some specific flow conditions. The interfacial tension force is the main source of instability, but viscosity and inertial forces also significantly affect the transition of stratified flow. Furthermore, the results indicated that the stabilizing effect of interfacial tension is the force responsible for the stability of the stratified flow studied in this work. The neutral stability transition boundary from stratified smooth to wavy stratified was predicted by applying a general stability criterion.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"189 ","pages":"Article 105253"},"PeriodicalIF":3.6,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143879152","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}

{"title":"Direct numerical simulation of non-Newtonian fluid droplets in homogeneous isotropic turbulence","authors":"Yidu Xiang,&nbsp;Shuai Wang,&nbsp;Haiou Wang,&nbsp;Kun Luo,&nbsp;Jianren Fan","doi":"10.1016/j.ijmultiphaseflow.2025.105262","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105262","url":null,"abstract":"<div><div>Droplet breakup and dispersion in turbulent flows have broad applications in engineering, yet the interaction between turbulence and non-Newtonian droplet breakup still lacks understanding. This study investigates the breakup dynamics of Newtonian and non-Newtonian droplets in forced homogeneous isotropic turbulence using high-fidelity numerical simulations based on the mass-conservation level set method. The simulations consider the effects of shear-thinning viscosity and turbulent stress on droplet deformation, fragmentation, and distribution. The results show that non-Newtonian droplets exhibit higher resistance to fragmentation, forming larger fragments due to faster vortex dissipation and reduced turbulent stress at the interface. In contrast, Newtonian droplets undergo rapid fragmentation, resulting in smaller, more uniform droplets. This work provides new insights into turbulence-induced droplet breakup mechanisms and offers a foundation for future optimization of non-Newtonian fluid applications.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"189 ","pages":"Article 105262"},"PeriodicalIF":3.6,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143876567","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}

{"title":"Comparative analysis of volume of fluid and phase–field methods for numerical simulations of two-phase flows","authors":"Daniele Rossi ,&nbsp;Simone Di Giorgio ,&nbsp;Sergio Pirozzoli","doi":"10.1016/j.ijmultiphaseflow.2025.105245","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105245","url":null,"abstract":"<div><div>A comprehensive study is conducted to analyze various methods for capturing the fluid interface in numerical simulations of two-phase flows. The primary objective is to compare the performance of volume of fluid (VOF) methods, based on a sharp interface description, and phase-field (PF) methods, where diffuse transition layers are used instead. To this end, a series of numerical simulations is conducted by using an in-house solver with four different interface-capturing methods: an algebraic TVD-VOF (AVOF), a geometric PLIC-VOF (GVOF), and two PF methods, based respectively on the conservative Allen–Cahn (CAC) and profile-corrected Cahn–Hilliard (CCH) formulations. These simulations aim to reproduce commonly used benchmark test cases as well as more complex practical applications, such as oceanic wave breaking and the sloshing phenomena of fluids within containers. The results highlighted the strengths and weaknesses of each method under various conditions, offering insights into their accuracy and computational costs. Among the methods, the GVOF approach consistently demonstrated higher accuracy in predicting the interface geometry, along with superior grid convergence properties, making it a reliable choice for a wide range of numerical simulations. The AVOF method offers a reliable alternative, delivering accurate results but facing some challenges in capturing smaller fluid structures and showing performance degradation in highly nonlinear scenarios. The PF methods are less accurate in predicting interface geometry, but perform better in terms of surface tension accuracy, yielding reduced spurious currents. The CAC method proves computationally efficient and simple to implement but faces time step limitations that necessitate future improvement for high-fidelity simulations. Finally, the CCH method performs least accurately across test conditions and it also incurs the highest computational cost among the methods tested. These outcomes may provide valuable insights for researchers in selecting the most suitable numerical method for their specific applications.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"189 ","pages":"Article 105245"},"PeriodicalIF":3.6,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143873323","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}

{"title":"Investigation on flow characteristics of highly viscous oil-water core-annular flow in horizontal pipes based on machine learning","authors":"Jie Sun ,&nbsp;Yuxin Zheng ,&nbsp;Liyao Jiang ,&nbsp;Cuiping Yang ,&nbsp;Chuanhao Huang ,&nbsp;Nana Sun ,&nbsp;Weidong Li ,&nbsp;Amos Ullmann ,&nbsp;Neima Brauner","doi":"10.1016/j.ijmultiphaseflow.2025.105265","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105265","url":null,"abstract":"<div><div>Water-annulus technology is regarded as a promising and efficient method for reducing drag and saving power in the transportation of highly viscous oil. Most existing theoretical prediction models for high-viscosity oil-water core-annular flow in horizontal pipes are based on a concentric core-annular flow configuration with a circular oil core and a smooth oil-water interface. In reality, however, this ideal configuration may not be achieved due to the buoyant force resulting from the density difference between the oil and water, and the instability of the interface. This discrepancy leads to a significant deviation between predicted results and experimental values for flow characteristics, particularly the pressure gradient and water holdup. Therefore, this study proposes a back propagation neural network model enhanced by particle swarm optimization to predict these flow characteristics for highly viscous oil-water core-annular flow in horizontal pipes. The model is trained and tested using experimental data obtained in experimental studies reported in the literature. The results indicate that the new model achieves high prediction accuracy for both pressure gradients and water holdups, significantly surpassing the accuracy of existing phenomenological models for core-annular flow. This proposed modeling approach has the potential to be a powerful tool for design and flow optimization in the petroleum industry.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"189 ","pages":"Article 105265"},"PeriodicalIF":3.6,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143864668","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}

{"title":"A novel microfluidic method to produce monodisperse micrometer bubbles","authors":"A. Rubio,&nbsp;S. Rodríguez-Aparicio,&nbsp;J.M. Montanero,&nbsp;M.G. Cabezas","doi":"10.1016/j.ijmultiphaseflow.2025.105249","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105249","url":null,"abstract":"<div><div>We present a novel microfluidic method to produce quasi-monodisperse bubbles with diameters from tens to very few microns. A gaseous rivulet flows over the shallow groove printed on a T-junction exit channel. The triple contact line delimiting the rivulet is pinned to the groove edges. The rivulet breaks up into bubbles much smaller than the exit channel. When operating under adequate conditions, the flow transitions toward a singular mode where the rivulet remains quasi-static and emits bubbles smaller than the groove width. This allows the production of bubbles with diameters in the 3-<span><math><mrow><mn>5</mn><mspace></mspace><mi>μ</mi><mi>m</mi></mrow></math></span> range, which is preferable for relevant therapeutical applications.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"190 ","pages":"Article 105249"},"PeriodicalIF":3.6,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143917473","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}

{"title":"Droplet evaporation on bio-inspired surfaces considering the electric field based on MRT-LBM","authors":"Bowen Yu,&nbsp;Zhiguo Xu,&nbsp;Zelin Zhao","doi":"10.1016/j.ijmultiphaseflow.2025.105267","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105267","url":null,"abstract":"<div><div>Droplet collisions on superheated solid surfaces under the electric field are universal phenomenon in both nature and industrial production processes. The electric field intensity and textured surface morphology are crucial factors influencing droplet evaporation. However, the understanding of how droplets impact and evaporate on textured surfaces with the electric field is limited. The research investigates how droplets morphologically change upon impacting superheated bio-inspired surfaces under the electric field, based on the multiphase and thermal multiple-relaxation-time lattice Boltzmann method that incorporates the leaky dielectric model. The bio-inspired surfaces, characterized by reentrant pillars, are designed based on the cuticles of springtails. Factors such as electric capillary number, Weber number, and microstructural morphology are taken into account for the effects of droplet collision and evaporation. The results indicate that an enhanced electric field promotes droplet evaporation during film evaporation. Nevertheless, in the context of nucleate boiling, the enhanced electric field does not consistently facilitate droplet evaporation. When the ratio of substrate temperature to critical temperature <span><math><mrow><mo>(</mo><mrow><msub><mi>T</mi><mi>h</mi></msub><mo>/</mo><msub><mi>T</mi><mi>c</mi></msub></mrow><mo>)</mo></mrow></math></span> is 0.90 and the Weber number is 85.5, the droplet breaks through the energy barriers of the structure, even without the electric field. Droplet lifetime on the superheated bio-inspired surface is shortest when <span><math><mrow><mrow><msub><mi>T</mi><mi>h</mi></msub><mo>/</mo><msub><mi>T</mi><mi>c</mi></msub></mrow><mo>=</mo><mn>0.90</mn><mo>,</mo><mn>1.02</mn><mo>,</mo><mn>1.06</mn></mrow></math></span> with the electric field, measuring 76.27 %, 46.36 %, and 56.78 % of that on the micro-pillar surface, respectively. This study provides valuable insights into accurately controlling electric fields to enhance the evaporation of droplets.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"189 ","pages":"Article 105267"},"PeriodicalIF":3.6,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143852035","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}

{"title":"Hagen–Poiseuille flow in the pipe layered by porous medium is linearly unstable","authors":"Ajay Sharma ,&nbsp;P. Bera ,&nbsp;Gaurav Sharma","doi":"10.1016/j.ijmultiphaseflow.2025.105243","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105243","url":null,"abstract":"&lt;div&gt;&lt;div&gt;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 (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;) and Beavers-Joseph slip coefficient (&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;B&lt;/mi&gt;&lt;mi&gt;J&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;) are fixed at &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;6&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and 0.1, respectively, the threshold value of thickness ratio, &lt;span&gt;&lt;math&gt;&lt;mover&gt;&lt;mrow&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;ˆ&lt;/mo&gt;&lt;/mrow&gt;&lt;/mover&gt;&lt;/math&gt;&lt;/span&gt; is around 0.0336. Our results show that the threshold value of &lt;span&gt;&lt;math&gt;&lt;mover&gt;&lt;mrow&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;ˆ&lt;/mo&gt;&lt;/mrow&gt;&lt;/mover&gt;&lt;/math&gt;&lt;/span&gt; increases monotonically with an increase in &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. 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 &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;B&lt;/mi&gt;&lt;mi&gt;J&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; destabilizes the flow, and the onset of instability takes place at Reynolds number as small as 695, when &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;6&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;B&lt;/mi&gt;&lt;mi&gt;J&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mover&gt;&lt;mrow&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;ˆ&lt;/mo&gt;&lt;/mrow&gt;&lt;/mover&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;016&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. Furthermore, an increase in &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;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}

{"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}

{"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}