European Journal of Mechanics B-fluids最新文献

{"title":"Dynamics of physiological blood flow in non-planar curved artery models","authors":"Sepideh Salimi,&nbsp;Hamid Sadat","doi":"10.1016/j.euromechflu.2025.204396","DOIUrl":"10.1016/j.euromechflu.2025.204396","url":null,"abstract":"<div><div>High-fidelity simulations are conducted to analyze physiological flows in non-planar curved artery models using physiological flow rates under pulsatile flow conditions. Additional simulations are performed under steady flow conditions at various Reynolds numbers, as well as for planar curved models for comparison. The results indicate that the torsion-induced effects are more pronounced under pulsatile flow than in steady conditions. During the acceleration phase, streamwise velocity peaks near the outer-upper wall close to the inlet and gradually shifts toward the outer-lower wall downstream, reinforcing asymmetric centrifugal effects. As flow transitions to deceleration, the streamwise velocity weakens, but the secondary flows intensify, further highlighting the influence of torsion. These asymmetric secondary flows lead to pronounced differences between the upper and lower deformed Dean (DD) vortices, with the lower DD vortex typically becoming larger and more persistent. Torsion also alters the trajectory and strength of deformed Lyne (DL) and split-Dean (SD) vortices, resulting in earlier vortex splitting and more complex interactions along the pipe, including asymmetric merging between upper and lower structures. Furthermore, torsion alters the wall shear stress (WSS) patterns, leading to asymmetric WSS distributions with localized regions of elevated and reduced WSS on the upper and lower walls, along with high oscillatory behavior throughout the cardiac cycle.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"116 ","pages":"Article 204396"},"PeriodicalIF":2.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145340696","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":"Development of a novel empirical correlation for vortex head in gravitational water vortex","authors":"Nayab ,&nbsp;Taqi Ahmad Cheema ,&nbsp;Naveed Razzaq Butt ,&nbsp;Atif Muzaffar ,&nbsp;Rizwan Ullah","doi":"10.1016/j.euromechflu.2025.204399","DOIUrl":"10.1016/j.euromechflu.2025.204399","url":null,"abstract":"<div><div>Gravitational vortex systems (GVS) are defined as systems that leverage gravitational vortices for applications such as energy generation and heat transfer in basins free from obstructions. These basins are commonly of two types: cylindrical and conical. Under the given flow conditions, fluid properties, and geometric dimensions of the basin, the vortex rises to a certain height, termed as the vortex head, which is the most crucial parameter for designing these systems. However, the absence of predictive tools for vortex head often leads to basin designs that fail to form a proper vortex head, causing overflow or turbine submergence in vortex powerplants, or uneven heating in vortex basins used for heat exchangers. Traditional methods regulate the flowrate to control the vortex head in vortex basins, but this approach compromises the strength of the vortex. To address this, an empirical framework has been developed to predict the vortex head based on flow conditions, fluid properties, and basin geometry. The correlation includes four dimensionless numbers: the orifice-to-basin diameter ratio (d/D), a geometric-to-flow parameters ratio, a vortex strength number (V_N), and free stream turbulence (FST). The applicability of the model is limited to cylindrical and conical basins without internal obstructions, for diameter ratios up to d/D ≤ 0.18, and with water used as the only working fluid. Statistical evaluation of the model shows a high degree of accuracy, with a coefficient of determination (R²) of 0.942, root means square error (RMSE) of 0.073 and mean average error (MAE) of 0.054. Residual error analysis confirms the consistency and reliability of the predictions. The model estimates vortex head within a ± 20 % tolerance and offers a practical design tool for laboratory-scale setups and industrial-scale gravitational vortex applications.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"116 ","pages":"Article 204399"},"PeriodicalIF":2.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145414862","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":"Dancing marbles in a soap film","authors":"Youna Louyer ,&nbsp;Benjamin Dollet ,&nbsp;Isabelle Cantat ,&nbsp;Anaïs Gauthier","doi":"10.1016/j.euromechflu.2025.204423","DOIUrl":"10.1016/j.euromechflu.2025.204423","url":null,"abstract":"<div><div>Two millimeter-sized particles deposited in a large horizontal soap film are attracted towards each other. Due to the very low friction at the surface of the soap film, the particles can exhibit a complex trajectory, and appear to dance together for about ten seconds before colliding. We give here a short overview of the topic and its perspectives.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"116 ","pages":"Article 204423"},"PeriodicalIF":2.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145615191","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":"Effect of momentum flux ratio on the flow and combustion behavior of coaxial jets with annular blockage","authors":"Shiferaw Regassa Jufar ,&nbsp;Minh Duc Le","doi":"10.1016/j.euromechflu.2025.204415","DOIUrl":"10.1016/j.euromechflu.2025.204415","url":null,"abstract":"<div><div>The flow and combustion characteristics of coaxial jets with annular blockage have been studied numerically. The model was validated with experimental results from related studies. Based on the observations presented in the study, two dominant flow regimes were identified as the momentum flux ratio varied. These regimes can be classified as either central or annular jet-dominated, based on the nature of the vortical structures and stagnation points in the flow field. The central jet-dominated flow occurs at momentum flux ratios below 0.25, where entrainment in the inner mixing region plays a key role. In contrast, the annular jet-dominated flow, which occurs at momentum flux ratios above 2.5, enhances mixing through the recirculation of streams within the counter-rotating vortex rings. In combustion, low momentum flux ratios result in longer flame lengths due to the absence of stagnation points and counter-rotating vortex rings, which lead to poor mixing performance. At higher momentum flux ratios, the formation of counter-rotating vortex rings and the stagnation points enhance mixing, resulting in shorter flame lengths and improved combustion performance. The novelty of this study lies in defining the characteristic flow regimes based on the Reynolds numbers of the annular and central jets, which helps distinguish the dominant flow modes. For a given Reynolds number of the jets, the prevailing mode can be identified to optimize both mixing and combustion performance.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"116 ","pages":"Article 204415"},"PeriodicalIF":2.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145517387","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":"Development of aeroacoustic control devices for a square cylinder using adjoint lattice Boltzmann method","authors":"Kazuya Kusano","doi":"10.1016/j.euromechflu.2025.204413","DOIUrl":"10.1016/j.euromechflu.2025.204413","url":null,"abstract":"<div><div>The control of aerodynamic noise is essential in various fields, including mechanical and aerospace engineering applications such as pantographs of high-speed trains and aircraft landing gears. Traditional devices, such as splitter plates, have long been employed to suppress wake flows and the resulting noise; however, the development of novel devices that outperform these classical designs has yet to be achieved. The present study seeked to develop innovative control devices using an aeroacoustic optimization framework that integrates the lattice Boltzmann method (LBM) with the adjoint method to modify the rear surface of a square cylinder. The Reynolds number was set to 150 for a two-dimensional laminar flow, and the Mach number was set to 0.2. The optimization created a ridge shape near the rear edge. Flow and acoustic analyses using the LBM showed that this shape successfully suppressed wake flow oscillations and mitigated the generation of aeolian tones. Additionally, a new passive control technique, namely, the installation of tapered splitter plates near the rear edge of the square cylinder, was proposed by simplifying the optimized shape. The LBM simulations demonstrated that the tapered splitter plates outperformed the conventional straight splitter plates in controlling the wake flow and flow-induced sound of the square cylinder.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"116 ","pages":"Article 204413"},"PeriodicalIF":2.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145517712","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":"Differential equation based wall distance approaches for maritime engineering flows","authors":"Niklas Kühl","doi":"10.1016/j.euromechflu.2025.204418","DOIUrl":"10.1016/j.euromechflu.2025.204418","url":null,"abstract":"<div><div>This study investigates differential-equation-based formulations for computing wall-distance functions in Computational Fluid Dynamics (CFD). The wall distance directly influences turbulence modeling by controlling near-wall damping functions and blending behavior, and is particularly critical for industrial applications, for example in maritime contexts involving complex ship geometries and flow configurations. Several approaches are compared, including linear and nonlinear <em>p</em>-Poisson, Screened-Poisson, Eikonal, regularized Eikonal/Hamilton–Jacobi, and Laplace methods. Each formulation is discretized and assessed for numerical stability, efficiency, and accuracy against an exact geometric benchmark.</div><div>The validated models are applied to hydrodynamic and aerodynamic ship flows. For a model-scale bulk carrier (<span><math><mrow><mi>R</mi><msub><mrow><mi>e</mi></mrow><mrow><mi>L</mi></mrow></msub><mo>=</mo><mn>7</mn><mo>.</mo><mn>2</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>6</mn></mrow></msup></mrow></math></span>, <span><math><mrow><mi>F</mi><mi>n</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>142</mn></mrow></math></span>), Reynolds-Averaged Navier–Stokes (RANS) simulations with Shear Stress Transport (SST) turbulence show that different wall-distance formulations alter resistance, trim, and sinkage by less than 0.1%. A temporally constant wall-distance field proves sufficient for accurate propulsion predictions. In contrast, a full-scale feeder ship (<span><math><mrow><mi>R</mi><msub><mrow><mi>e</mi></mrow><mrow><mi>L</mi></mrow></msub><mo>=</mo><mn>5</mn><mo>.</mo><mn>0</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>8</mn></mrow></msup></mrow></math></span>) analyzed with a hybrid RANS/LES (IDDES) model exhibits greater sensitivity to wall-distance definitions.</div><div>Among the tested methods, the convective Eikonal or Hamilton–Jacobi formulations with deferred correction achieve the best compromise between robustness, computational cost, and accuracy, whereas <em>p</em>-Poisson and Screened-Poisson variants are more parameter-sensitive and computationally expensive.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"116 ","pages":"Article 204418"},"PeriodicalIF":2.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145569182","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":"2026-01-01","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":"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":"2026-01-01","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":"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":"2026-01-01","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":"Lseq2seq: A new reduced-order model for unsteady aerodynamic force identification","authors":"Yihua Pan ,&nbsp;Xiaomin An ,&nbsp;Yuqi Lei ,&nbsp;Xin Gao ,&nbsp;Chen Ji","doi":"10.1016/j.euromechflu.2025.204377","DOIUrl":"10.1016/j.euromechflu.2025.204377","url":null,"abstract":"<div><div>Identifying unsteady aerodynamic forces is a crucial and challenging task in aerodynamics. It is also a critical research foundation for other subjects such as aeroelasticity, aircraft design, and flight dynamics. The two mainstream methods used to identify unsteady aerodynamic forces are Computational Fluid Dynamics (CFD) and experiments. However, these methods have their limitations, such as lengthy computational expense and high resource consumption. This article proposes a new reduced-order model called Long Sequence to Sequence (Lseq2seq) based on deep sequence generation models to predict unsteady aerodynamic forces in an efficient way. The Lseq2seq model is then applied to determine the hysteresis loop for the NACA0012 airfoil and the unsteady aerodynamic force of the two-freedom oscillation of the NACA64A010 airfoil in transonic flow. The results are compared with other prevalent time-sequential networks, such as Sequence to Sequence (Seq2seq) and Gated Recurrent Unit (GRU). The proposed Lseq2seq model presents better precision and generalization ability for identification. Additionally, this article explores a combined predictor–corrector method called GRU-Lseq2seq to predict the flutter response of the NACA64A010 airfoil, and the results demonstrate that the combined model could achieve better prediction accuracy than the GRU model and could be used in flutter boundary prediction.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"115 ","pages":"Article 204377"},"PeriodicalIF":2.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145155625","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}