International Journal of Multiphase Flow最新文献

{"title":"Impact dynamics of self-rotating droplets on superhydrophobic surfaces","authors":"Yifu Shu ,&nbsp;Jiaxing Song ,&nbsp;Shaokang Li ,&nbsp;Jia Luo ,&nbsp;Yanhui Feng ,&nbsp;Fuqiang Chu","doi":"10.1016/j.ijmultiphaseflow.2025.105449","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105449","url":null,"abstract":"<div><div>Droplet impact on superhydrophobic surfaces has attracted significant attention due to its relevance to a wide range of engineering applications, such as anti-icing, self-cleaning and hydroelectric generation. In practice, droplets rarely fall vertically without initial motion. Aerodynamic and external disturbances often impart rotation, which significantly influences their impact dynamics. However, the impact dynamics of droplets with initial angular velocity on superhydrophobic surfaces remain poorly understood. Here, we investigate the dynamics of self-rotating droplets impacting superhydrophobic surfaces through numerical simulations, covering a broad range of droplet initial angular velocities from 0 to 700 rad/s. We find that increasing the droplet initial angular velocity leads to stronger centrifugal forces and higher rotational kinetic energy, which affects the balance between inertial and capillary forces, thereby enhancing droplet spreading and significantly reducing the contact time. Further, we systematically analyze how angular velocity influences both spreading and retraction stages, revealing critical mechanisms governing droplet behavior under rotational conditions. Based on these mechanisms, scaling laws are derived to accurately predict the maximum spreading coefficient and the contact time, demonstrating excellent agreement with the simulation results. These findings enhance the understanding of self-rotating droplet dynamics on superhydrophobic surfaces and provide guidance for related practical applications.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"194 ","pages":"Article 105449"},"PeriodicalIF":3.8,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145106584","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":"Numerical simulation study on stratified flow boiling in rectangular mini-channels","authors":"Wei Lu ,&nbsp;Xiucheng Yu ,&nbsp;Zonghui Lu ,&nbsp;Dongxu Han ,&nbsp;Xi Wang ,&nbsp;Yujie Chen ,&nbsp;Xueke Luo ,&nbsp;Yanru Yang ,&nbsp;Xiaodong Wang","doi":"10.1016/j.ijmultiphaseflow.2025.105447","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105447","url":null,"abstract":"<div><div>In this study, the flow boiling heat transfer in a rectangular mini-channel with stratified flow is investigated using the VOSET method. Different heat transfer performances are observed in stratified flow compared to fill liquid flow. The effects of merging, fluctuation, fragmentation, and lifting are observed in stratified flow boiling, which are absent in fill liquid flow. The positive fluctuation and merging effects reduce the dry patch area on the wall. Large bubbles merge into the upper vapor layer upon contacting the free surface. Meanwhile, fluctuations in the free surface reduce the detachment radius of the bubbles and increase their detachment frequency. These positive effects lead to a reduction in wall superheat by up to 27.86 %. However, at high heat fluxes, negative fragmentation effect emerges. Intense boiling can cause the thin liquid film to fragment, increasing the area of dry patches. Despite this, the positive effects of merging and fluctuation still greater than the negative impact of fragmentation, resulting in a slight enhancement in overall heat transfer performance. Additionally, the liquid height ratio (<em>LHR</em>), defined as the ratio of the liquid film height (<em>H_L</em>) to the channel height (<em>H</em>), significantly impacts stratified flow boiling. For thicker liquid films, the heating wall is isolated by the vapor because of the negative lifting effect. This lifting effect drastically reduces the rewetting of the heating wall, leading to a significant deterioration in overall heat transfer performance. However, this negative lifting effect can be mitigated by adjusting the <em>LHR</em>. In practical operations, adjusting the liquid level height can promote heat transfer performance in mini-channel flow boiling.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"194 ","pages":"Article 105447"},"PeriodicalIF":3.8,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145106589","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 sliding on an inclined substrate with chemical defects","authors":"Jing-Wei Chen,&nbsp;Chun-Yu Zhang,&nbsp;Peng Gao,&nbsp;Hao-Ran Liu,&nbsp;Hang Ding","doi":"10.1016/j.ijmultiphaseflow.2025.105445","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105445","url":null,"abstract":"<div><div>We numerically study the dynamics of a droplet sliding on an inclined and inhomogeneous substrate under gravity force using three-dimensional diffuse interface method. On the path of the sliding droplet, there are two transversely located defects with the shape of circle, and their wettability is different from the substrate. Our aim is to identify the regimes of the droplet motion and figure out the critical conditions between the different regimes. By varying the distance between the two defects, the inclination angle of the substrate, and the size of the defects, three regimes are found according to the status of the droplet: capture, breakup and release. By analyzing geometrical relationships, the shape of the contact line and the force balance of the droplet at rest, we derive critical conditions between each two regimes. The theoretical predictions of critical conditions agree well with our numerical simulations, which provide a comprehensive understanding of the underlying mechanisms of a droplet sliding on a chemical defect substrate.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"194 ","pages":"Article 105445"},"PeriodicalIF":3.8,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145106585","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":"Impact of anisotropic porosity on electroosmotic flow of micropolar fluid in wavy channel","authors":"Neelima Ghiya,&nbsp;Ashish Tiwari","doi":"10.1016/j.ijmultiphaseflow.2025.105444","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105444","url":null,"abstract":"<div><div>The influence of weak anisotropy on electroosmotic flow of micropolar fluids in geometrically non-uniform microchannels is explored through a comprehensive theoretical framework. Using a rigorous mathematical framework, a comprehensive model is developed that couples the Poisson–Boltzmann equation governing the electric double layer dynamics and the Brinkman equation with the micro rotational term. To tackle this difficulty, the perturbation technique is employed to resolve the coupled equations with appropriate boundary conditions, where the channel’s aspect ratio (<span><math><mrow><mi>δ</mi><mo>≪</mo><mn>1</mn></mrow></math></span>) is taken as the perturbation parameter. A comprehensive analysis is conducted to examine the effects of critical parameters such as the Debye–Hückel parameter, anisotropic ratio, fluctuation parameter, micro-scale parameter (<span><math><mi>m</mi></math></span>), and coupling parameter (<span><math><mi>N</mi></math></span>) on various flow characteristics. The findings indicate that a stronger micropolar effect leads to a decrease in linear velocity near the wavy wall, while a contrasting increase in linear velocity is observed at greater distances from the wall. The velocity profiles computed numerically using the finite difference method show negligible difference between solutions from linearized Poisson–Boltzmann equations (Debye–Hückel approximation) and non-linear Poisson–Boltzmann equations for weak anisotropy. These findings have significant implications for optimizing microfluidic devices in biomedical applications, chemical separation processes, and micro-scale heat exchangers where precise flow control is paramount.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"194 ","pages":"Article 105444"},"PeriodicalIF":3.8,"publicationDate":"2025-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145118385","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 numerical study on the clustering characteristics of rising air bubbles in stagnant water","authors":"Ingu Lee ,&nbsp;Haecheon Choi","doi":"10.1016/j.ijmultiphaseflow.2025.105419","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105419","url":null,"abstract":"<div><div>We perform numerical simulations of rising air bubbles in stagnant water to investigate their clustering characteristics. Monodispersed rising bubbles are simulated in a periodic computational box for three cases of bubble equivalent diameters (<span><math><mrow><msub><mrow><mi>d</mi></mrow><mrow><mi>e</mi><mi>q</mi></mrow></msub><mo>=</mo><mn>0</mn><mo>.</mo><mn>5</mn><mo>,</mo><mn>1</mn></mrow></math></span> and 1.5 mm), respectively. The bubble cluster is identified based on an inter-bubble-distance criterion (Ma et al., 2023) and its characteristics is analyzed. Initially, the bubbles are uniformly distributed throughout the domain. The bubbles with <span><math><mrow><msub><mrow><mi>d</mi></mrow><mrow><mi>e</mi><mi>q</mi></mrow></msub><mo>=</mo><mn>0</mn><mo>.</mo><mn>5</mn><mspace></mspace><mi>mm</mi></mrow></math></span> retain their initial distribution, while those with <span><math><mrow><msub><mrow><mi>d</mi></mrow><mrow><mi>e</mi><mi>q</mi></mrow></msub><mo>=</mo><mn>1</mn></mrow></math></span> and 1.5 mm interact among themselves, leading to clustering. For the larger bubbles (<span><math><mrow><msub><mrow><mi>d</mi></mrow><mrow><mi>e</mi><mi>q</mi></mrow></msub><mo>=</mo><mn>1</mn></mrow></math></span> and 1.5 mm), simulations with a small horizontal domain size result in a stable formation of domain-full horizontal bubble clustering. However, when the horizontal domain size is sufficiently large, such clustering no longer occurs, but local sheet-like clustering, aligned nearly parallel to the horizontal direction, occurs. During bubble collision and bouncing-off, a counter-rotating vortex pair is generated and induces a downward velocity on the bubbles, which decreases their rising velocity and keeps the bubbles horizontally aligned.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"194 ","pages":"Article 105419"},"PeriodicalIF":3.8,"publicationDate":"2025-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145106587","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":"Single deformed bubbles rising through stagnant water of surfactant concentrations beyond CMC","authors":"Yusei Iwai ,&nbsp;Shigeo Hosokawa ,&nbsp;Dominique Legendre ,&nbsp;Kosuke Hayashi","doi":"10.1016/j.ijmultiphaseflow.2025.105440","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105440","url":null,"abstract":"<div><div>Experiments were conducted on deformed bubbles in Triton X-100 aqueous solutions at concentrations exceeding the critical micelle concentration (CMC) to understand the bubble behavior in the so-called fully-contaminated state. The terminal velocity was significantly reduced at a concentration <span><math><mi>C</mi></math></span> of 10 mmol/m³ (<span><math><mrow><mo>&lt;</mo><mi>CMC</mi><mo>=</mo><mn>240</mn></mrow></math></span> mmol/m³), and the velocity data were in agreement with the well-known slow velocity curve for contaminated systems. However, as indicated in <span><math><mi>C</mi></math></span> beyond CMC, the terminal velocity experienced a further decrease, while the velocities at concentrations of <span><math><mrow><mi>C</mi><mo>=</mo><mn>10</mn><mo>,</mo><mn>000</mn></mrow></math></span> and 20,000 mmol/m³ were the same, suggesting that at these concentrations the bubbles were completely contaminated. In the <span><math><mrow><mi>R</mi><mi>e</mi></mrow></math></span>-<span><math><mrow><mi>E</mi><mi>o</mi></mrow></math></span> plane, where the Eötvös number was calculated by the effective surface tension, <span><math><msub><mrow><mi>σ</mi></mrow><mrow><mi>e</mi><mi>q</mi></mrow></msub></math></span>, for the equilibrium of adsorption and desorption, the bubble Reynolds numbers of contaminated bubbles agreed with those in a higher viscosity system with the effective Morton number for <span><math><msub><mrow><mi>σ</mi></mrow><mrow><mi>e</mi><mi>q</mi></mrow></msub></math></span>. Therefore, bubbles were considered to be fully covered by surfactant, which causes the surface tension reduction and the Marangoni effect. The presence of surfactant decreased the shape deformation, and the aspect ratios for <span><math><mrow><mi>C</mi><mo>=</mo><mn>10</mn><mo>,</mo><mn>000</mn></mrow></math></span> and 20,000 mmol/m³ were the same, again showing that the bubbles at these concentrations were fully contaminated. The Weber number defined for <span><math><msub><mrow><mi>σ</mi></mrow><mrow><mi>e</mi><mi>q</mi></mrow></msub></math></span> worked well to correlate the shapes of contaminated bubbles. A shape correlation for contaminated bubbles was developed, and an available drag correlation was extended by introducing the effects of bubble deformation to reproduce the fast and slow velocity curves of clean and contaminated bubbles that exhibit different characteristics in shape and path oscillations, in particular at <span><math><mi>C</mi></math></span> beyond CMC.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"194 ","pages":"Article 105440"},"PeriodicalIF":3.8,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145060843","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 particle–fluid simulation of spherical and ellipsoidal particles in turbulent pipe-free-jet flow","authors":"Thede Kiwitt,&nbsp;Matthias Meinke,&nbsp;Dominik Krug,&nbsp;Wolfgang Schröder","doi":"10.1016/j.ijmultiphaseflow.2025.105443","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105443","url":null,"abstract":"<div><div>The dynamics of spherical and ellipsoidal particles in coupled turbulent pipe-free-jet flow at Reynolds number <span><math><mrow><mi>R</mi><msub><mrow><mi>e</mi></mrow><mrow><mi>D</mi></mrow></msub><mo>=</mo><mn>15</mn><mspace></mspace><mn>546</mn></mrow></math></span> is analyzed by direct particle–fluid simulation. The jet is laden with spherical and ellipsoidal particles with aspect ratios in the range <span><math><mrow><mn>1</mn><mo>≤</mo><mi>β</mi><mo>≤</mo><mn>8</mn></mrow></math></span> with a volume loading of <span><math><mrow><mn>6</mn><mo>.</mo><mn>67</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>4</mn></mrow></msup></mrow></math></span> supplied by turbulent periodic pipe flow. The flow field is predicted using a finite-volume formulation on an adaptively refined Cartesian mesh. Each particle is fully resolved by a cut-cell method. The method guarantees the conservation of mass, momentum, and energy at the fluid–particle interfaces. To ensure physically correct particle distributions and flow field characteristics, a slicing technique is used to determine the instantaneous solution of a simultaneously computed particle–laden fully-developed turbulent pipe flow that defines the inflow boundary distribution of the jet. The fluid and particle statistics within fully-developed turbulent pipe and free jet flow are investigated independent from each other. Preferential particle distributions, orientations, and time-averaged energy exchange rates are analyzed with emphasis on the impact of the varying particle aspect ratios. The ellipsoidal particles tend to align closer to the particle center than spherical particles in the turbulent pipe. Furthermore, the energy exchange rates and the particle-induced dissipation tend to differ such that the anisotropic particles exchange more energy with the fluid close to the pipe wall. The impact of the particles on the pipe flow influences the turbulent free jet flow for which it serves as inflow condition. Overall, the spreading rate of the particle–laden turbulent free jet is reduced due to the increased fluid dissipation rate. Furthermore, due to the non-spherical particles the kinetic energy of the fluid is lowered by 9% and the turbulence intensity is decreased by approx. 20% at the end of the near field.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"194 ","pages":"Article 105443"},"PeriodicalIF":3.8,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145046469","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":"Analysis of the vortex-pressure coupling mechanism in cavitation dynamics for self-excited oscillation nozzles and its structural optimization","authors":"Songlin Nie,&nbsp;Yuwei Song,&nbsp;Hui Ji,&nbsp;Junzhou Meng,&nbsp;Yixuan Zhang,&nbsp;Fanglong Yin","doi":"10.1016/j.ijmultiphaseflow.2025.105442","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105442","url":null,"abstract":"<div><div>This study investigates cavitation dynamics in a self-excited oscillation nozzle (SEON) under gravitational influence using high-speed imaging, computational fluid dynamics (CFD) simulations, Proper Orthogonal Decomposition (POD), wavelet analysis, and multi-objective optimization with Dynamic Adaptive NSGA-II (DANSGA-II). High-speed imaging displays the formation, detachment, and collapse of cavitation cloud. CFD simulations reveal the internal flow field and vapor distribution, clarifying cavitation evolution in the SEON chamber. POD and wavelet analyses demonstrate a nonlinear relationship between cavitation behavior and inlet pressure, with peak performance at 1.5 MPa. A novel vortex-pressure pulsation coupling mechanism was proposed to explain cavitation cloud development. This mechanism guided structural optimization by selecting chamber length (<em>L</em>), impingement wall angle (<em>α</em>), and outlet contraction ratio (<em>d</em>₂/<em>D</em>) as design variables. Multi-objective optimization using DANSGA-II produced optimal nozzle designs. For example, in Case 1 (<em>L</em> = 10.1 mm, <em>α</em> = 103°, <em>d</em>₂/<em>D</em> = 0.1881), the mean vapor volume fraction increased by 59.18 %, and turbulent kinetic energy rose by 32.32 %. Methylene blue degradation experiments showed a 15.88 % removal efficiency after 120 minutes, improving 77.8 % over the baseline. This study investigated a vortex-pressure coupling mechanism through integrated visualization and simulation techniques, thereby facilitating the structural optimization of SEONs and enhancing cavitation performance. The findings provide both theoretical insights and practical guidance for the design and application of SEONs in industrial cleaning and wastewater treatment processes.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"194 ","pages":"Article 105442"},"PeriodicalIF":3.8,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145046360","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":"Surface-wettability dependent water-driving-oil two-phase flow in heterogeneous nanochannels","authors":"Yiheng Su,&nbsp;Rui Wang,&nbsp;Bofeng Bai,&nbsp;Chengzhen Sun","doi":"10.1016/j.ijmultiphaseflow.2025.105441","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105441","url":null,"abstract":"<div><div>For the oil-water two-phase flow process in nanochannels, the oil-water wettability of the surface has a significant impact on the flow characteristics. When the wettabilities of the upper and lower surfaces are different, many interesting phenomena occur inside the channels, but no studies have been reported. This work investigates water-driving-oil two-phase flow in heterogeneous nanochannels using molecular dynamics simulations coupled with comparisons to a well-established theoretical model. As one wall evolves from hydrophilic to hydrophobic while the opposite remains hydrophilic, the flow regime sequentially evolves from symmetric-meniscus, asymmetric-meniscus, transition, to oil-film-attached flow, with variations depending on channel height and driving pressure. Flow rates exhibit nonlinear dependence on driving pressure with variations across regimes. Comparing with the theoretical model developed for predicting the time-varying imbibition length in homogeneous channels, considerable deviations are observed in asymmetric-meniscus, transition, and oil-film-attached regimes owing to additional resistances arising from heterogeneous capillary forces and oil-film adhesion.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"194 ","pages":"Article 105441"},"PeriodicalIF":3.8,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145046359","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":"Beyond direction-agnostic assumptions: Direction-integrated models for asymmetric falling film thickness and heat transfer under multidirectional vapor shear","authors":"Chuang-Yao Zhao ,&nbsp;Qiong-Tao Li ,&nbsp;Chen-Yi Jia ,&nbsp;Fang-Fang Zhang ,&nbsp;Di Qi ,&nbsp;Hasan Yildizhan ,&nbsp;Jun-Min Jiang","doi":"10.1016/j.ijmultiphaseflow.2025.105439","DOIUrl":"10.1016/j.ijmultiphaseflow.2025.105439","url":null,"abstract":"<div><div>The orientation of vapor streams in falling film evaporators (FFEs), determined by tube bundle configurations, plays a critical role in shaping liquid film hydrodynamics and heat transfer performance. Conventional models adopt direction-agnostic assumptions, averaging vapor shear effects and introducing significant errors in localized predictions. This study proposes a direction-integrated framework that explicitly incorporates vapor orientation as a governing parameter, capturing the asymmetric effects of multidirectional vapor shear on film thickness and heat transfer. The proposed correlations are validated against a broad range of benchmark data, achieving 80 % of film thickness predictions within ±25 % error, over 86 % of local heat transfer coefficients within ±20 %, and all average values within ±5 %. Comparative analysis shows strong agreement with experimental and numerical results under gravity-driven, laminar conditions. Vapor directionality is shown to significantly alter heat transfer along the tube periphery, especially between upper and lower regions. These findings enhance the predictive reliability of FFE modelling and provide valuable guidance for optimizing evaporator design and improving energy efficiency in industrial applications.</div></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"194 ","pages":"Article 105439"},"PeriodicalIF":3.8,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144997478","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}