International Journal of Multiphase Flow最新文献_第4页

Dry-Wet degradation process of unsaturated metamorphic sandstone based on multi-field coupling mechanism: A Case study of the protection of Damaidi rock art 基于多场耦合机制的非饱和变质砂岩干湿降解过程——以大麦地岩画保护为例

IF 3.8 2区工程技术 Q1 MECHANICS

International Journal of Multiphase Flow

Pub Date : 2025-12-30 DOI: 10.1016/j.ijmultiphaseflow.2025.105598

Guopeng Wu , Jiacheng Sui , Zhuohang Tian , Zhijie Zhao , Guanghao Yu , Ruiying Zhang , Qiangqiang Pei , Kai Cui

This study investigates the accelerated deterioration of Damaidi rock art after summer rainfall, revealing the dry-wet degradation mechanisms of metamorphic sandstone. Based on conservation laws of mass, energy, and momentum, as well as unsaturated porous media theory, the Van Genuchten model is applied to describe water infiltration in unsaturated rock. The model accounts for solid matrix and pore fluid compressibility, thermal effects on fluid flow, and water vapor phase changes impacting rock deformation, establishing a coupled thermal-hydro-mechanical (THM) mathematical framework. Using COMSOL Multiphysics, numerical simulations of the dry-wet degradation process were conducted and validated against experimental data, including temperature, volumetric water content, and stress-strain curves. Key findings include: 1) Spatial heterogeneity in temperature and moisture fields, with boundary effects decaying with depth and a linear increase in temperature response lag; 2) Increased secondary porosity leading to a 17.8% rise in water diffusion coefficient by the 5th cycle; 3) Differential strain up to 0.12% from THM coupling, forming microcrack networks. The simulation results match experimental data with an average relative error below 8.2%, verifying the model’s accuracy in representing THM coupling behavior in unsaturated rock. These insights provide a theoretical foundation for understanding the weathering mechanisms of rock art substrates.

研究了夏季降雨后大麦地岩画的加速变质过程，揭示了变质砂岩干湿降解机制。基于质量、能量和动量守恒定律，结合非饱和多孔介质理论，将Van Genuchten模型应用于非饱和岩石中水的入渗。该模型考虑了固体基质和孔隙流体的可压缩性、热效应对流体流动的影响以及水气相变化对岩石变形的影响，建立了热-水-力耦合数学框架。使用COMSOL Multiphysics，对干湿降解过程进行了数值模拟，并根据实验数据进行了验证，包括温度、体积含水量和应力-应变曲线。主要发现包括：1)温度和湿度场的空间异质性，边界效应随深度衰减，温度响应滞后线性增加；2)第5次循环时，次生孔隙度增加，水扩散系数增加17.8%；3)由THM耦合产生的差应变高达0.12%，形成微裂纹网络。模拟结果与实验数据吻合，平均相对误差小于8.2%，验证了模型对非饱和岩石中THM耦合行为的描述准确性。这些见解为理解岩画基质的风化机制提供了理论基础。

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引用次数: 0

Adaptively reconstructed spectral eddy-viscosity in large eddy simulations of particle-laden isotropic turbulence, Part I: Particle statistics at low Reynolds number 大涡模拟中自适应重建谱涡黏度的粒子负载各向同性湍流，第一部分：低雷诺数下的粒子统计

IF 3.8 2区工程技术 Q1 MECHANICS

International Journal of Multiphase Flow

Pub Date : 2025-12-29 DOI: 10.1016/j.ijmultiphaseflow.2025.105584

Michał Rajek , Jacek Pozorski

Large eddy simulations (LES) of isotropic turbulence coupled with the Lagrangian particle tracking have consistently been disregarded as a means of exploring the physics underlying turbulent dispersed two-phase flows, specifically at Reynolds numbers beyond the reach of direct numerical simulations (DNS). In the current two-part study we focus on evaluating the impact of our recently developed adaptively reconstructed spectral eddy-viscosity on the dynamics of inertial particles in LES of isotropic turbulence. To confirm the robustness of our computational framework, in the present work we first concentrate on the settling speed enhancement, clustering, and relative velocities at low Reynolds numbers. These particle statistics are of importance to determining the collision rates, influencing various environmental phenomena and industrial processes. We also indicate that the LES enriched with a well-established spectral eddy-viscosity which assumes the existence of an infinite

k^{- 5 / 3}

energy spectrum is unable to reliably predict the radial distribution function and the radial relative velocities at contact. We show that the adaptively reconstructed eddy-viscosity significantly improves the predictive capabilities of LES, thus providing a tool to explore the physics underlying dispersed two-phase flows. We particularly demonstrate that under conditions relevant to cloud turbulence, certain phenomena related to particle motion can be accurately predicted without the subgrid-scale contribution to the fluid velocity at the particle location. In the companion paper we assess the ability of the proposed LES to accurately quantify particle clustering at length scales relevant to the inertial subrange at high Reynolds numbers.

各向同性湍流的大涡模拟（LES）与拉格朗日粒子跟踪相结合，一直被忽视为探索湍流分散两相流的物理基础的手段，特别是在直接数值模拟（DNS）无法达到的雷诺数下。在目前的两部分研究中，我们重点评估了我们最近开发的自适应重建光谱涡流粘度对各向同性湍流LES中惯性粒子动力学的影响。为了证实我们的计算框架的鲁棒性，在目前的工作中，我们首先关注低雷诺数下的沉降速度增强、聚类和相对速度。这些粒子统计对于确定碰撞率、影响各种环境现象和工业过程具有重要意义。我们还指出，假设存在无限k−5/3能谱，且具有完善的谱涡黏度的LES不能可靠地预测接触时的径向分布函数和径向相对速度。我们发现自适应重建的涡流粘度显著提高了LES的预测能力，从而为探索分散两相流的物理基础提供了工具。我们特别证明，在与云湍流有关的条件下，某些与粒子运动有关的现象可以准确地预测，而不需要亚网格尺度对粒子位置流体速度的贡献。在配套论文中，我们评估了所提出的LES在高雷诺数下与惯性子范围相关的长度尺度上精确量化粒子聚类的能力。

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引用次数: 0

Nanoscale mapping of competitive cavitation nucleation: From surface to bulk 竞争空化成核的纳米尺度映射：从表面到体

IF 3.8 2区工程技术 Q1 MECHANICS

International Journal of Multiphase Flow

Pub Date : 2025-12-26 DOI: 10.1016/j.ijmultiphaseflow.2025.105595

Yuhan Li , Junhao Cai , Yunqiao Liu , Mingbo Li , Benlong Wang

The prevailing view that pits are more susceptible to cavitation nucleation than pillars has spurred extensive research on pit scenarios; however, competition among bulk, pit surface, or pillar surface nucleation under a broader range of wettability has received limited attention. Therefore, nanoscopic molecular dynamics simulations (MD) and classical nucleation theory (CNT) are employed to elucidate the competitive nucleation diagram across the three nucleation pathways. Results reveal that bulk nucleation can still out-compete surface nucleation provided the entire rough wall exhibits extreme super-wettability; however, achieving this wetting state is highly demanding. In contrast, pit-embedded surface nucleation dominates when the rough wall features uniformly weak wettability. The Blake threshold constitutes the metastable equilibrium of vapor bubbles confined within pits. Weakly wettable pillars on strongly hydrophilic substrates prevail in the competitive cavitation nucleation; however, they exert an insignificant influence when the substrate is also weakly hydrophilic, thereby allowing pit-embedded surface nucleation to dominate. The nucleation mode phase diagram establishes a universal framework for predicting the cavitation nucleation across a tailored wettability regime, offering fundamental significance to nucleation research.

普遍认为矿坑比矿柱更容易发生空化成核的观点促使了对矿坑情景的广泛研究；然而，在更广泛的润湿性范围内，块状、坑表面或柱表面成核之间的竞争受到了有限的关注。因此，采用纳米级分子动力学模拟（MD）和经典成核理论（CNT）来阐明三种成核途径的竞争成核图。结果表明，当整个粗糙壁表现出极端的超润湿性时，体形核仍能优于表面形核；然而，实现这种湿润状态的要求很高。相反，当粗糙壁具有均匀的弱润湿性时，坑埋表面成核占主导地位。布莱克阈值构成了局限于凹坑内的蒸汽泡的亚稳态平衡。在强亲水性基质上弱可湿性柱在竞争性空化成核中占优势；然而，当底物也是弱亲水性时，它们的影响不显著，从而使坑埋表面成核占主导地位。成核模式相图为预测特定润湿性条件下的空化成核建立了一个通用框架，对成核研究具有重要意义。

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引用次数: 0

Collision-induced breakup dynamics of binary equal-sized nanodroplets 二元等尺寸纳米液滴的碰撞诱导破碎动力学

IF 3.8 2区工程技术 Q1 MECHANICS

International Journal of Multiphase Flow

Pub Date : 2025-12-24 DOI: 10.1016/j.ijmultiphaseflow.2025.105593

Zongjun Yin, Chengbin Zhang, Yongping Chen

The role of scale effects on binary nanodroplet collision dynamics is profound, as interfacial forces exhibit strong size dependence at the nanoscale. This study employs molecular dynamics simulations to investigate head-on collisions of equal-sized water nanodroplets, focusing on rupture mechanisms and interfacial dynamics at the nanoscale. The effect of disjoining pressure on nanoscale interfacial phenomena is elucidated, demonstrating a marked increase in surface energy density in thin films and nanodroplets. Four distinct outcomes are identified: regular coalescence, coalescence after perforation, limited splattering, and divergent splattering, and a regime map is constructed accordingly. The rupture instability of nanosheets formed during binary nanodroplet collisions is dictated by thermocapillary short-wave instabilities, which govern the selection of the critical wavenumber. These instabilities initiate perforation at the periphery of the spreading meniscus and subsequently propagate inward once a critical nanosheet thickness is reached. However, the relevant scaling arguments regarding the critical nanosheet thickness remain to be satisfactorily determined. Therefore, the critical nanosheet thickness is calculated semi-empirically to scale with the nanoscale critical wavelength, demonstrating that the critical thickness intriguingly becomes an invariant value for the range of Ohnesorge numbers considered. Based on the scaled critical nanosheet thickness for nanodroplet breakup, a theoretical model is developed for collision-induced breakup dynamics of binary equal-sized nanodroplets, explicitly incorporating nanoscale disjoining pressure effects. The proposed model is validated against extensive numerical simulations, and good agreement is achieved, demonstrating its predictive power for nanoscale free-flow dynamics where classical theories fail.

尺度效应对二元纳米液滴碰撞动力学的影响是深远的，因为界面力在纳米尺度上表现出强烈的尺寸依赖性。本研究采用分子动力学模拟来研究等大小的纳米水滴的正面碰撞，重点研究纳米尺度上的破裂机制和界面动力学。研究了分离压力对纳米级界面现象的影响，表明薄膜和纳米液滴的表面能密度显著增加。确定了四种不同的结果：规则聚结、穿孔后聚结、有限飞溅和发散飞溅，并据此构建了一个制度图。热毛细短波的不稳定性决定了二元纳米液滴碰撞形成的纳米片的破裂不稳定性，而热毛细短波的不稳定性决定了临界波数的选择。这些不稳定性在扩展的半月板外围引发穿孔，并随后向内传播，一旦达到临界纳米片厚度。然而，关于临界纳米片厚度的相关缩放参数仍有待确定。因此，临界纳米片厚度的计算是半经验的，与纳米尺度临界波长成比例，表明临界厚度在考虑的欧内格数范围内成为一个不变值。基于纳米液滴破碎的临界纳米片厚度，建立了二元等尺寸纳米液滴碰撞诱导破碎动力学的理论模型，明确地考虑了纳米尺度的分离压力效应。通过大量的数值模拟验证了该模型的有效性，并取得了良好的一致性，证明了该模型对纳米尺度自由流动动力学的预测能力。

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引用次数: 0

How substrate temperature shapes Salmonella Typhimurium deposition patterns and pathogenesis in evaporating droplets 底物温度如何影响鼠伤寒沙门氏菌在蒸发液滴中的沉积模式和发病机制

IF 3.8 2区工程技术 Q1 MECHANICS

International Journal of Multiphase Flow

Pub Date : 2025-12-23 DOI: 10.1016/j.ijmultiphaseflow.2025.105592

Amey Nitin Agharkar , Anmol Singh , Kush Kumar Dewangan , Dipshikha Chakravortty , Saptarshi Basu

Droplets expelled from infected hosts can deposit on surfaces and serve as fomites. Temperature‑controlled industrial equipment is also susceptible to such contamination. To test the hypothesis that substrate temperature influences droplet behaviour, we examined how temperatures from 25 °C to 70 °C affect evaporation dynamics, internal flows, deposition patterns, bacterial viability, and infectivity in Salmonella Typhimurium–laden droplets. Milli‑Q water, Luria broth (LB) medium, and meat extract were used as representative physiological fluids. Imaging and confocal microscopy techniques were used to study the evaporation dynamics and flow, whilst the morphology of dried precipitates was characterised using microscopy and profilometry. The classical “coffee-ring” deposition is exhibited at low temperatures for S. Typhimurium-Milli-Q water droplet. However, as the substrate temperature rises, thermal gradients generate strong inward Marangoni convection that competes with the capillary flow, producing thinner rings or central deposits for Milli-Q water and with dendritic structures for LB. Meanwhile, for meat extract, the patterns remained unchanged. The measured radial velocities at 50 °C were ten times higher than at 25 °C. Increased substrate temperatures resulted in a drastic reduction of the evaporation time and a decreased bacterial area of projection, keeping the bacterial aspect ratio intact. It depicted higher stress due to faster evaporation. The viability of Salmonella in precipitates was reduced with increasing substrate temperature, but infectivity remained unaltered across all base fluids.

Thus, the findings show that substrate temperature highly influences bacterial deposition and viability. The potential fomite-based infection risks from heated surfaces are outlined.

被感染的宿主排出的飞沫可以沉积在物体表面并作为污染物。温控工业设备也容易受到这种污染。为了验证底物温度影响液滴行为的假设，我们研究了25°C至70°C的温度如何影响鼠伤寒沙门氏菌液滴的蒸发动力学、内部流动、沉积模式、细菌活力和传染性。Milli‑Q水、Luria肉汤（LB）培养基和肉提取物作为代表性生理液体。成像和共聚焦显微镜技术用于研究蒸发动力学和流动，而干燥沉淀物的形态使用显微镜和轮廓术进行表征。在低温条件下，鼠伤寒沙门氏菌- milliq水滴表现出经典的“咖啡环”沉积。然而，随着衬底温度的升高，热梯度产生强烈的向内马兰戈尼对流，与毛细管流动竞争，对milliq水产生更薄的环或中心沉积物，对LB产生树枝状结构。同时，对于肉提取物，模式保持不变。在50°C时测得的径向速度比在25°C时高10倍。升高的底物温度导致蒸发时间急剧减少，细菌投影面积减少，保持细菌长宽比完整。它描述了由于蒸发更快而产生的更高压力。沙门氏菌在沉淀物中的生存能力随着底物温度的升高而降低，但感染性在所有底液中保持不变。因此，研究结果表明，底物温度高度影响细菌的沉积和生存能力。概述了加热表面潜在的基于污染物的感染风险。

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引用次数: 0

Data-Free physics-informed neural networks for modeling compressible multiphase flows 模拟可压缩多相流的无数据物理信息神经网络

IF 3.8 2区工程技术 Q1 MECHANICS

International Journal of Multiphase Flow

Pub Date : 2025-12-22 DOI: 10.1016/j.ijmultiphaseflow.2025.105589

Rui Liu , Zitong Zhao , Jili Rong

Physics-informed neural networks (PINNs), which formulate loss functions based on the residuals of governing equations, have gained increasing attention for modeling fluid mechanics. However, in compressible flows, the differential form of hyperbolic conservation laws breaks down near discontinuities due to the absence of derivatives. This limitation presents a significant challenge for data-free PINN frameworks. The challenge is further intensified in multiphase flows, where contact discontinuities exhibit more complex structures and interactions, and relevant studies remain limited. To address these challenges, this study proposes a multiphase PINN model incorporating an encoder-decoder convolutional long short-term memory (ConvLSTM) deep learning framework to enable deep feature extraction and global residual computation. A multiphase Godunov-type finite volume method (FVM) loss function is developed based on a highly robust five-equation model. By employing a Godunov-type discretization derived from the weak form of the conservation laws, the framework circumvents the limits associated with strong-form discontinuities. This approach ensures entropy consistency while achieving high-resolution shock capturing in discontinuous regions. Due to the inherent dissipation of the modeling approach, the interface thickness tends to increase over time during flow evolution, which degrades the prediction accuracy of the model. To address this limitation, an improved loss function with interface anti-diffusion properties is proposed to effectively suppress interface smearing and enhance prediction fidelity. Through training and extrapolative prediction on various one-dimensional Riemann problems and high-dimensional shock cases, the proposed multiphase PINN model demonstrates accurate interface tracking and high precision in discontinuous regions. The multiphase PINN model developed in this study offers a novel predictive framework for a broad range of compressible multiphase flow problems.

基于物理信息的神经网络（pinn）基于控制方程的残差制定损失函数，在模拟流体力学方面受到越来越多的关注。然而，在可压缩流动中，由于缺乏导数，双曲守恒定律的微分形式在不连续点附近失效。这一限制对无数据PINN框架提出了重大挑战。在多相流中，接触不连续面表现出更复杂的结构和相互作用，这一挑战进一步加剧，相关研究仍然有限。为了解决这些挑战，本研究提出了一个包含编码器-解码器卷积长短期记忆（ConvLSTM）深度学习框架的多相PINN模型，以实现深度特征提取和全局残差计算。基于高鲁棒五方程模型，建立了多相godunov型有限体积法（FVM）损失函数。通过采用由守恒律的弱形式导出的godunov型离散化，该框架绕过了与强形式不连续相关联的限制。这种方法确保了熵的一致性，同时实现了在不连续区域的高分辨率冲击捕获。由于建模方法固有的耗散，在流动演化过程中界面厚度随时间的增加而增加，从而降低了模型的预测精度。为了解决这一问题，提出了一种具有界面抗扩散特性的改进损失函数，以有效抑制界面涂抹，提高预测保真度。通过对各种一维黎曼问题和高维激波情况的训练和外推预测，所提出的多相PINN模型在不连续区域具有准确的界面跟踪和较高的精度。本研究建立的多相PINN模型为广泛的可压缩多相流问题提供了一个新的预测框架。

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引用次数: 0

Hybrid Eulerian–Lagrangian approach for direct numerical simulations of elastic turbulence 弹性湍流直接数值模拟的欧拉-拉格朗日混合方法

IF 3.8 2区工程技术 Q1 MECHANICS

International Journal of Multiphase Flow

Pub Date : 2025-12-22 DOI: 10.1016/j.ijmultiphaseflow.2025.105587

F. Serafini

Direct Numerical Simulation (DNS) is a fundamental tool for studying elastic turbulence (ET), as the polymer stresses that trigger ET are not directly accessible experimentally. We discuss a hybrid Eulerian–Lagrangian approach for DNS, and we show that the main ET features can be consistently observed in a wide range of concentrations and Weissenberg numbers. The hybrid approach does not require a larger resolution compared to fully Eulerian simulations, with the advantage of more accurate predictions of the polymer stress, and a clear link between model parameters and real polymer properties. Furthermore, a Lagrangian description of the polymer phase allows to explore the limiting, but realistic, conditions of small concentration and large Weissenberg number.

直接数值模拟（DNS）是研究弹性湍流（ET）的基本工具，因为触发ET的聚合物应力无法通过实验直接获得。我们讨论了一种用于DNS的欧拉-拉格朗日混合方法，并且我们表明，在广泛的浓度和Weissenberg数范围内，可以一致地观察到主要的ET特征。与全欧拉模拟相比，混合方法不需要更大的分辨率，其优点是更准确地预测聚合物应力，并且模型参数与实际聚合物性质之间有明确的联系。此外，拉格朗日描述的聚合物相允许探索限制，但现实的条件下，小浓度和大的Weissenberg数。

引用次数: 0

Sedimentation and resistance tensor of a river floc from 3D X-ray microtomography 三维x射线微层析成像的河流絮体沉降和阻力张量

IF 3.8 2区工程技术 Q1 MECHANICS

International Journal of Multiphase Flow

Pub Date : 2025-12-22 DOI: 10.1016/j.ijmultiphaseflow.2025.105586

Chuan Gu , Heng Li , Kate L. Spencer , Lorenzo Botto

Natural sediment flocs are highly porous particulate aggregates composed of biogenic and minerogenic materials. They can be an important component of suspended sediment load in rivers, estuaries and the marine environment and modelling floc dynamics and behaviour is very important for many aquatic industries, maintenance of waterways and conservation and management of aquatic water bodies. X-ray computed microtomography has recently been applied to quantify the complex three-dimensional (3D) geometry of natural sediment flocs. Here, X-ray images of 3 selected natural millimetre-sized flocs sampled from the Thames River have been digitalised and converted into geometries used in Stokesian Dynamics calculations of the hydrodynamic properties of the flocs, where each floc is represented as a rigid ensemble of spherical beads moving in the creeping flow regime. Our approach is a substantial step from previous attempts in which synthetic fractal structures were simulated. In addition to describe the complex dynamics of floc settling, we compute: (i) the hydrodynamic radius of the flocs; (ii) the floc mobility and resistance tensors; and (iii) the relation between sedimentation velocity and fractal dimension. The simulations show that the coupling of gravitational forces with lateral velocities, which we analysed by examining the cross-components of the mobility matrix, produces a helical motion of the flocs as they settle. We argue that this lateral motion may lead to an enhancement of floc–floc aggregation by differential sedimentation due to an increase in the effective collisional area. Furthermore, the simulations demonstrate significant differences in the dynamics of settling between the three flocs despite a similar gross shape. Our work exemplifies how high-resolution X-ray techniques can be coupled with accurate particle-resolved simulations to understand the settling dynamics of real (as opposed to synthetic) flocs collected from estuarine, coastal or waste-water environments.

天然沉积物絮凝体是由生物和成矿物质组成的高多孔颗粒聚集体。它们可以是河流、河口和海洋环境中悬浮泥沙负荷的重要组成部分，对浮群动力学和行为进行建模对许多水产工业、水道的维护以及水生水体的养护和管理非常重要。最近，x射线计算机微断层扫描被用于量化天然沉积物絮凝体复杂的三维（3D）几何形状。在这里，从泰晤士河采样的3个天然毫米大小的絮凝体的x射线图像已经被数字化并转换成几何形状，用于絮凝体流体动力特性的斯托克动力学计算，其中每个絮凝体都被表示为在蠕动流动状态下移动的球形珠子的刚性集合。我们的方法是一个实质性的步骤，从以前的尝试中，合成分形结构的模拟。除了描述絮凝体沉降的复杂动力学外，我们还计算了：(i)絮凝体的水动力半径；（ii）絮体流动性和阻力张量；(3)沉降速度与分形维数的关系。模拟表明，重力与横向速度的耦合，我们通过检查迁移矩阵的交叉分量来分析，在絮凝体沉降时产生螺旋运动。我们认为，由于有效碰撞面积的增加，这种横向运动可能会导致絮凝体聚集的增强。此外，模拟表明，尽管大体形状相似，但三种絮凝体之间的沉降动力学存在显着差异。我们的工作举例说明了高分辨率x射线技术如何与精确的颗粒分辨率模拟相结合，以了解从河口，海岸或废水环境中收集的真实（与合成）絮凝体的沉降动力学。

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引用次数: 0

Flow transition of liquid–liquid two-phase Taylor–Couette flow with axial flow 液-液两相Taylor-Couette轴向流动的流动转变

IF 3.8 2区工程技术 Q1 MECHANICS

International Journal of Multiphase Flow

Pub Date : 2025-12-19 DOI: 10.1016/j.ijmultiphaseflow.2025.105585

Hayato Masuda, Yuta Kikuchi, Hiroyuki Iyota

A liquid–liquid two-phase Taylor–Couette flow is of fundamental and practical importance in multiphase flow systems. This study investigates the flow transitions in such a system with constant axial flow and gradually increased rotation of the inner cylinder. To clarify the effect of continuous-phase viscosity on flow transitions, several concentrations of glycerol–water solutions were employed as the continuous phase, while soybean oil was used as the dispersed phase. Visualization experiments revealed that the flow undergoes a cascade of transitions: stratified flow, disturbed stratified flow, transitional droplet flow, unstable banded flow, and stable banded flow. A flow map was constructed using two dimensionless parameters, rotational Reynolds number (Re_rot) and Weber number (We). The transitions from disturbed stratified to unstable banded flow (TR I) and from unstable to stable banded flow (TR II) were found to be approximately expressed by a power-law relation of the form We ∼ Re_rot^A, where A is a fitting exponent. For TR I, A showed no clear dependence on continuous-phase viscosity, suggesting that the transition is governed by the combined effects of inertia, viscosity, and interfacial tension. In contrast, A decreased with increasing viscosity in TR II, becoming nearly zero at high glycerol concentration. Furthermore, to clarify the mechanism of stable banded flow formation, the droplet inertia was evaluated using the Stokes number (St). It was revealed that the stable banded structure results from the loss of droplet inertia, associated with droplet fragmentation under higher rotation and the increasing inertia of the continuous phase.

液-液两相泰勒-库埃特流在多相流系统中具有重要的基础和实际意义。本文研究了在轴向流量恒定、内缸转速逐渐增大的情况下系统的流动转变。为了明确连续相粘度对流动转变的影响，采用几种浓度的甘油-水溶液作为连续相，大豆油作为分散相。可视化实验表明，流动经历了层叠流、扰动层叠流、过渡液滴流、不稳定带状流和稳定带状流的级联过渡。利用旋转雷诺数（Rerot）和韦伯数（We）这两个无维参数构建了流图。从扰动分层到不稳定带状流（TR I）和从不稳定到稳定带状流（TR II）的转变可以用We ~ RerotA形式的幂律关系近似表示，其中a是拟合指数。对于TR I， A对连续相粘度没有明显的依赖性，表明这种转变是由惯性、粘度和界面张力共同作用的结果。相比之下，在TR II中，A随着粘度的增加而降低，在高甘油浓度时接近于零。此外，为了阐明稳定带状流动形成的机制，利用Stokes数（St）对液滴惯性进行了评估。结果表明，稳定的带状结构是由于液滴惯性的丧失，与高转速下液滴破碎和连续相惯性的增加有关。

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引用次数: 0

Experimental study of pressure effect on the evolution of slug/pseudo slug flow characteristics in a large diameter slightly upward inclined pipe 压力对大直径微上斜管内段塞/伪段塞流动特性演化的影响实验研究

IF 3.8 2区工程技术 Q1 MECHANICS

International Journal of Multiphase Flow

Pub Date : 2025-12-18 DOI: 10.1016/j.ijmultiphaseflow.2025.105583

Ahmed A. Aql , G. Soto-Cortes , E. Al-Safran , E. Pereyra , C. Sarica

This study experimentally investigates the effect of pressure on slug evolution along an 85 m long, 0.156 m ID, and +2° inclined pipe, operated at pressures under 200 and 400 psi, using advanced tracking sensors and topology instruments. The results show that slugs form earlier at lower pressures of 200 psi and undergo more pronounced growth and dissipation cycles, attributed to greater gas compressibility caused by the lower gas-to-liquid density ratio. Additionally, at a pressure of 200 psi, slugs grow more rapidly along the pipe compared to 400 psi. In contrast, results reveal that at higher pressure conditions of 400 psi, the transition from pseudo slug to fully developed slug is delayed due to wave crest breakage. Additionally, mean slug and film lengths grow with distance but exhibit cyclic fluctuations. At the low pressure, these lengths are relatively greater. Additionally, slug frequency decreases more rapidly with distance at low pressure than at high pressure, reflecting a higher rate of slug and wave coalescence.

本研究利用先进的跟踪传感器和拓扑仪器，实验研究了压力对85 m长、0.156 m内径、+2°倾斜管段塞演化的影响，该管段在200和400 psi压力下作业。结果表明，在较低的200 psi压力下，段塞形成得更早，并且经历了更明显的生长和耗散循环，这是由于较低的气液密度比导致了更高的气体压缩性。此外，与400psi压力相比，在200psi压力下，段塞沿着管道生长得更快。相反，结果表明，在400psi的高压条件下，由于波峰破碎，从伪段塞流到完全发育的段塞流的过渡被延迟。此外，平均段塞和膜的长度随距离增长，但表现出周期性波动。在低压下，这些长度相对较大。此外，在低压条件下，段塞流频率随距离的下降速度比高压条件下更快，这反映出段塞流与波的结合速度更快。

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