European Journal of Mechanics B-fluids最新文献

{"title":"Influences of particle-particle and particle-wall interactions on the settling behaviors of the centimeter-sized spherical particles","authors":"Lun Sun ,&nbsp;Ri Zhang ,&nbsp;Zhongwei Zhou ,&nbsp;Jifu Yin ,&nbsp;D.D. Meringolo","doi":"10.1016/j.euromechflu.2025.204387","DOIUrl":"10.1016/j.euromechflu.2025.204387","url":null,"abstract":"<div><div>This paper experimentally investigates the effect of particle-particle and particle-wall interactions on the settling process of spherical particles. A convergence binocular calibration technique was used to capture the settling process under three typical conditions: (a) individual spherical particles settling at the center of the tank, (b) individual spherical particles settling near the wall, and (c) two symmetric spherical particles settling at the center of the tank. The ratio of initial particle-particle or particle-wall gap to the particle diameter is defined as a dimensionless parameter <em>Gap.</em> For individual particles released near the wall, when <em>Gap</em> is within 1.5, the wall significantly suppresses the random deflection characteristics typically observed for individual spherical particles settling at the tank center. Similarly, for two symmetric particles, random deflection is markedly suppressed, with highly symmetrical settling velocities and trajectories. The settling behavior of an individual spherical particle near the wall closely resembles that of the wall-facing particle in the symmetric-pair case, indicating that the wall effectively acts as a mirror. Additionally, <em>Gap</em> exerts little influence on the final mean settling velocity for either individual particles released near the wall or twin particles released at the center of the water tank.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"115 ","pages":"Article 204387"},"PeriodicalIF":2.5,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145267615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on the influence of the rotational degree of freedom on the heat transfer of single-y vibrating blunt bodies","authors":"Qingchun Zhou,&nbsp;Xiaowei Liu,&nbsp;Chunji Hu","doi":"10.1016/j.euromechflu.2025.204388","DOIUrl":"10.1016/j.euromechflu.2025.204388","url":null,"abstract":"<div><div>Active rotation is commonly employed in traditional enhanced heat dissipation applications. However, passive rotation, which operates without external energy input, leverages environmental energy more effectively, showing great potential for enhanced heat transfer applications. This study explores the impact of passive rotation on the heat transfer characteristics of single-degree-of-freedom transverse vibrations in circular cylinders and square prisms. Numerical simulations were performed under the conditions of <em>Re</em> = 100, <em>m</em>* = 2, <em>ζ</em> = 0, and <em>Pr</em> = 0.7. The results show that the rotational degree of freedom has minimal influence on the heat transfer of circular cylinders, with only a 1.11 % increase in Nusselt number. In contrast, it significantly enhances heat transfer in square prisms, leading to a 14.21 % increase. Further analysis reveals that the rotational degree of freedom transitions the vibration mode from pure vortex-induced vibration (VIV) to a combination of VIV and galloping, which is the primary mechanism behind the heat transfer enhancement. Flow field analysis indicates that this transition strengthens vortex intensity and disturbs the thermal boundary layer, providing a microscopic explanation for the observed heat transfer improvements. The introduction of rotational freedom in such systems offers a novel and effective approach to enhance heat transfer performance.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"115 ","pages":"Article 204388"},"PeriodicalIF":2.5,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145266752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 temperature dependent viscosity on thermo-bioconvective flow of Jeffrey fluid containing gravitactic microorganism in a permeable medium","authors":"Dhananjay Yadav ,&nbsp;Houda Al Maqbali ,&nbsp;Mukesh Kumar Awasthi ,&nbsp;Ravi Ragoju ,&nbsp;Saif Al Aghbari ,&nbsp;Maryam Al Aameriya ,&nbsp;Basama Al Hanai ,&nbsp;Asma Al Malki ,&nbsp;Ljina Al Aamri","doi":"10.1016/j.euromechflu.2025.204386","DOIUrl":"10.1016/j.euromechflu.2025.204386","url":null,"abstract":"<div><div>This study investigates how linear and exponential variations in temperature-dependent viscosity influence the initiation of thermo-bioconvective flow in a non-Newtonian Jeffrey fluid with gravitactic microorganisms present in a permeable medium, which has not been addressed in the existing literature. The threshold of the thermo-bioconvective flow, taking into account the absence of microorganism flux at the boundaries, is determined through linear stability theory, and the corresponding eigenvalue problem is resolved analytically using the Galerkin method. The findings indicate that when viscosity changes linearly with temperature, the critical Rayleigh number<span><math><msubsup><mrow><mi>R</mi></mrow><mrow><mi>D</mi><mo>,</mo><mi>c</mi></mrow><mrow><mi>E</mi><mi>x</mi></mrow></msubsup></math></span> at which the system starts convection is approximately 11 % higher than when viscosity changes exponentially with temperature. This shows that the system is more unstable when viscosity changes exponentially with temperature compared to a linear change. The stability of the arrangement decreases as the bio Rayleigh-Darcy number<span><math><msub><mrow><mi>R</mi></mrow><mrow><mi>B</mi><mi>D</mi></mrow></msub></math></span>, the bio Péclet number<span><math><mrow><mi>P</mi><msub><mrow><mi>e</mi></mrow><mrow><mi>B</mi></mrow></msub></mrow></math></span>, the Jeffrey factor<span><math><mi>γ</mi></math></span>, and the viscosity deviation parameter<span><math><mi>F</mi></math></span> increase. In instances of exponential viscosity variation with temperature, the size of the convective cells grows with the viscosity deviation parameter<span><math><mi>F</mi></math></span>, while it remains constant in the case of linear viscosity variation. Additionally, it is important to emphasize that oscillatory convective motion is not relevant to the current analysis.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"115 ","pages":"Article 204386"},"PeriodicalIF":2.5,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145267618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stabilization of drug droplet contact line via Bovine Serum Albumin Solution-Phase Additive","authors":"Josías N. Molina-Courtois ,&nbsp;Roxana Belen Pérez Hidalgo ,&nbsp;Yojana J.P. Carreón ,&nbsp;Carlos A. Martínez-Miwa ,&nbsp;Lourdes Díaz-Jiménez ,&nbsp;Mario Castelán ,&nbsp;Jorge González-Gutiérrez","doi":"10.1016/j.euromechflu.2025.204385","DOIUrl":"10.1016/j.euromechflu.2025.204385","url":null,"abstract":"<div><div>The method of pattern analysis in dried droplets has emerged as an effective tool for detecting adulterants in medications and diagnosing pathologies. However, despite numerous studies on the drying dynamics of droplets, there remains a need for effective methods to stabilize droplet contact line and achieve controlled coating. Finding alternative solutions for droplet stabilization could significantly improve the precision and efficacy in the application of the dry droplet pattern recognition method. In this study, we hypothesize that bovine serum albumin (BSA) can act as an effective tool for stabilizing the contact line of sessile methotrexate (MTX) drops, controlling pattern formation during the drying process. We evaluated BSA concentrations of 0.01, 0.1, 0.25, 0.5, 1, and 2% in MTX (10%) solutions; which, in the absence of BSA, become destabilized on polymethylmethacrylate (PMMA) substrates. Our results indicate that, starting from a concentration of 0.1% BSA, the methotrexate droplets are efficiently fixed, producing highly reproducible patterns. Using measurements of height profile, contact angle, and evaporation time, we found that BSA fixes the droplets and prevents the deformation of the contact line. Additionally, we observed that BSA modifies the interaction between the droplet and the substrate, improving adhesion and reducing the expansion or contraction of the droplets. Importantly, the stabilizing effect was only observed when BSA was present in solution; when BSA was pre-adsorbed onto the substrate, MTX droplets exhibited spreading and destabilization. We demonstrated that BSA promotes a homogeneous distribution of solutes and more uniform and controlled evaporation when acting as a solution-phase additive in MTX formulations. These findings indicate that BSA can serve as a functional modulator for enhancing reproducibility and controlling deposition in dropwise manufacturing of pharmaceutical coatings.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"115 ","pages":"Article 204385"},"PeriodicalIF":2.5,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145267616","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exact Riemann solutions for the drift-flux model of gas–liquid two-phase flows with van der Waals gas","authors":"Chunwang Yan ,&nbsp;Yanyan Zhang ,&nbsp;Yu Zhang","doi":"10.1016/j.euromechflu.2025.204383","DOIUrl":"10.1016/j.euromechflu.2025.204383","url":null,"abstract":"<div><div>We develop a van der Waals drift-flux model to describe gas–liquid two-phase flow and solve its Riemann problem analytically. Employing a unified parametric approach, we derive the exact expressions for all elementary waves and rigorously establish the existence and uniqueness of solutions. Additionally, we propose a simple criterion to determine whether shocks or rarefaction waves arise in the 1-family and 3-family. Finally, the theoretical analysis is confirmed by numerical simulation. This work presents a comprehensive analysis of the Riemann problem for the drift-flux model with non-ideal gas, providing an exact mathematical framework for studying the non-ideal two-phase flow dynamics.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"115 ","pages":"Article 204383"},"PeriodicalIF":2.5,"publicationDate":"2025-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145267617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 linear stability investigation of non-Darcian MHD flow in a vertical pipe via numerical methods","authors":"Ashok Kumar ,&nbsp;Anup Singh Negi ,&nbsp;Ashok Kumar","doi":"10.1016/j.euromechflu.2025.204379","DOIUrl":"10.1016/j.euromechflu.2025.204379","url":null,"abstract":"<div><div>This study investigates the linear stability of buoyancy-assisted Poiseuille flow of an electrically conducting fluid through a vertical porous pipe subjected to a transverse magnetic field. The flow behavior is modeled using the Brinkman-extended non-Darcy formulation to capture the influence of both viscous and inertial effects in a porous medium. A linear stability analysis is performed, and the consequential eigenvalue problem is solved numerically using the Chebyshev spectral collocation method. The impact of key dimensionless parameters, including the Prandtl number (<span><math><mrow><mi>P</mi><mi>r</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>01</mn></mrow></math></span> to 100), Darcy number (<span><math><mrow><mi>D</mi><mi>a</mi><mo>=</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span> to <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>4</mn></mrow></msup></mrow></math></span>), and Hartmann number (<span><math><mrow><mi>H</mi><mi>a</mi></mrow></math></span>), are systematically examined to understand their roles in flow stability. The results reveal that the base velocity profile exhibits an inflection point, and the applied magnetic field significantly alters both velocity and temperature distributions. For water (<span><math><mrow><mi>P</mi><mi>r</mi><mo>=</mo><mn>7</mn></mrow></math></span>), the flow exhibits least stability at higher magnetic influence (<span><math><mrow><mi>H</mi><mi>a</mi><mo>=</mo><mn>2</mn></mrow></math></span>), indicating the potential for enhanced heat transfer, particle dispersion, and flow manipulation. Conversely, for heavy oil (<span><math><mrow><mi>P</mi><mi>r</mi><mo>=</mo><mn>50</mn></mrow></math></span>), the flow is least stable without a magnetic field (<span><math><mrow><mi>H</mi><mi>a</mi><mo>=</mo><mn>0</mn></mrow></math></span>), highlighting magnetic field-based control strategies for applications such as thermal management, flow control, and smart fluidic devices. These findings offer important insights for optimizing magnetohydrodynamic flows in porous systems for engineering and industrial applications.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"115 ","pages":"Article 204379"},"PeriodicalIF":2.5,"publicationDate":"2025-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145217834","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparing the highly-resolved onset of Rayleigh–Taylor and Kelvin–Helmholtz Rayleigh–Taylor instabilities","authors":"Bhavna Joshi ,&nbsp;Aditi Sengupta ,&nbsp;Yassin Ajanif ,&nbsp;Lucas Lestandi","doi":"10.1016/j.euromechflu.2025.204382","DOIUrl":"10.1016/j.euromechflu.2025.204382","url":null,"abstract":"<div><div>The present study explores onset of Rayleigh–Taylor instability (RTI) and Kelvin–Helmholtz Rayleigh–Taylor instability (KHRTI) with highly-resolved direct numerical simulations of two setups considering air at different temperatures (or densities) and/or velocities in two halves of three-dimensional (3D) cuboidal domains. The RTI and KHRTI are simulated with 4.2 billion and 480 million mesh points, respectively. Here, we do not impose any external perturbation similar to the unforced experiments of RTI and KHRTI. The compressible Navier–Stokes equations are solved using a novel parallel algorithm which does not involve overlapping points at sub-domain boundaries. This removes the errors at sub-domain boundaries and provides same level of accuracy as sequential computing. The pressure disturbance field is compared during onset of RTI and KHRTI and corresponding convection- and advection-dominated mechanisms are highlighted by instantaneous features, spectra, and proper orthogonal decomposition. Relative contributions of pressure energy, kinetic energy and rotational energy to overall energy budget are explored, revealing acoustics to play a central role in initial perturbation for both RTI and KHRTI. The nonlinear, spatio-temporal nature of the instability is further explored by application of a transport equation for enstrophy of compressible flows. This provides insights into the similarities and differences between onset mechanisms of RTI and KHRTI, serving as a benchmark data set for shear and buoyancy-driven instabilities across diverse applications in geophysics, nuclear energy and atmospheric fluid dynamics.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"115 ","pages":"Article 204382"},"PeriodicalIF":2.5,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145217835","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cavity collapse associated with oil entry of steel spheres","authors":"Benedict C.-W. Tan","doi":"10.1016/j.euromechflu.2025.204381","DOIUrl":"10.1016/j.euromechflu.2025.204381","url":null,"abstract":"<div><div>The collapse of air cavity towards the liquid surface that occurred immediately after deep seal following vertical entry of steel spheres into a pool of oil, was experimentally investigated. The vertical displacement between the pinch-off depth and the cavity base during the time when the cavity was collapsing towards the surface, was regularly measured and analysed using images taken from a high-speed camera. Furthermore, some phenomena associated with the upward oil jet generated during cavity collapse were also described and briefly studied. The results suggested that the rate of cavity collapse towards the surface, and the time taken for the lower part of the oil jet to reach surface level, were dependent on both the inertial and gravitational forces of the spheres.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"115 ","pages":"Article 204381"},"PeriodicalIF":2.5,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145155615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stereoscopic valve flow path topology design in reciprocating compressors: Structural optimization via the response surface method","authors":"Xiao Hong,&nbsp;Weilin Cui,&nbsp;Dexi Wang,&nbsp;Dajing Liu,&nbsp;Xinrui Fu,&nbsp;Xiwen Cao","doi":"10.1016/j.euromechflu.2025.204378","DOIUrl":"10.1016/j.euromechflu.2025.204378","url":null,"abstract":"<div><div>The enhancement of energy efficiency in reciprocating compressor valves has long been constrained by the non-analytical nature of multi-parameter coupling effects. Traditional single-parameter strategies are inadequate for revealing the complex nonlinear interactions within flow paths. To address this limitation, this study proposes a response surface method (RSM)-based strategy for the topological optimization of stereoscopic flow channels. By constructing spatial interactions among contact surface tilt angles, flow path angles, and port-slot ratios, the study for the first time quantifies the influence of multi-parameter coupling mechanisms on effective flow area and flow coefficient. The optimal parameter combination obtained via RSM (<em>α</em>=71.8°, <em>β</em>=14.2°, <em>γ</em>=2:1) exhibited superior performance, as confirmed by both experimental and industrial tests: compared with the passive plate valve, the discharge volume increased by 50.1 % and the specific energy consumption per unit discharge volume decreased by 7.6 %; relative to the single-parameter numerical optimization group, the discharge volume further increased by 3.3 % and the specific energy consumption decreased by 2.7 %. The discrepancy between simulation and experimental results was less than 5 %, validating the reliability and accuracy of the proposed method. This study establishes an integrated methodological framework of “parameter coupling analysis-flow field characteristic regulation—system energy efficiency verification,” providing a novel paradigm for the intelligent design and energy-efficient optimization of high-performance fluid machinery.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"115 ","pages":"Article 204378"},"PeriodicalIF":2.5,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145217832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Linear stability of rotating pipe flow with non-ideal fluid","authors":"Congren Zheng ,&nbsp;Yong Chen ,&nbsp;Zijing Ding","doi":"10.1016/j.euromechflu.2025.204375","DOIUrl":"10.1016/j.euromechflu.2025.204375","url":null,"abstract":"<div><div>A linear stability analysis is performed on rotating pipe flow with a non-ideal fluid. The study focuses on supercritical CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> near its vapor–liquid critical point, where thermodynamic properties deviate significantly from ideal gas. Different wall temperatures are considered, ensuring centerline temperatures span subcritical, transcritical, and supercritical conditions. The modal analysis reveals that at low rotation speeds, unstable mode only exists at rotational speed <span><math><mrow><mi>Ω</mi><mo>&lt;</mo><mn>0</mn></mrow></math></span>. Also multiple unstable modes emerge, introducing a more complex instability mechanism compared to non-rotating pipe flow. As rotation speed increases, viscous dissipation plays a key role in flow stabilization, while thermodynamic effects remain secondary. The non-modal analysis further demonstrates that optimal system response under fixed-frequency forcing shifts due to rotation, with stronger deviations from incompressible behavior at high compressibility. In rotating pipe flow, the dependence of transient energy growth on the azimuthal wavenumber (<span><math><mi>n</mi></math></span>) is inherently nonlinear, which stands in stark contrast to the approximately linear relationship typically observed in non-rotating pipe flow. This nonlinearity arises primarily due to the influence of azimuthal velocity components introduced by rotation. These findings highlight the intricate coupling between rotation, compressibility, and thermodynamics, providing new insights into instability mechanisms in non-ideal fluid systems.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"115 ","pages":"Article 204375"},"PeriodicalIF":2.5,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145155616","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}