European Journal of Mechanics B-fluids最新文献_第7页

Dynamics of physiological blood flow in non-planar curved artery models 非平面弯曲动脉模型的生理血流动力学

IF 2.5 3区工程技术 Q2 MECHANICS

European Journal of Mechanics B-fluids

Pub Date : 2026-03-01 Epub Date: 2025-10-20 DOI: 10.1016/j.euromechflu.2025.204396

Sepideh Salimi, Hamid Sadat

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.

采用脉动流条件下的生理流速，对非平面弯曲动脉模型进行了高保真模拟。在不同雷诺数的稳定流动条件下进行了额外的模拟，并对平面弯曲模型进行了比较。结果表明，在脉动工况下，扭转效应比稳定工况下更为明显。在加速阶段，沿流速度在靠近进气道的外上壁附近达到峰值，并逐渐向下游的外下壁移动，增强了非对称离心效应。当气流向减速过渡时，向流速度减弱，但二次流加剧，进一步凸显了扭转的影响。这些不对称的二次流导致了上下形变迪安（DD）涡之间的显著差异，下形变迪安（DD）涡通常变得更大、更持久。扭转还会改变变形Lyne （DL）和分裂- dean （SD）涡流的轨迹和强度，导致涡流分裂更早，以及管道沿线更复杂的相互作用，包括上下结构之间的不对称合并。此外，扭转改变了壁面剪切应力（WSS）模式，导致壁面剪切应力分布不对称，在上下壁面局部区域WSS升高或降低，并在整个心脏周期中具有高振荡行为。

{"title":"Dynamics of physiological blood flow in non-planar curved artery models","authors":"Sepideh Salimi, 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}

引用次数: 0

Development of a novel empirical correlation for vortex head in gravitational water vortex 重力水涡中涡头的一种新的经验相关的发展

IF 2.5 3区工程技术 Q2 MECHANICS

European Journal of Mechanics B-fluids

Pub Date : 2026-03-01 Epub Date: 2025-10-23 DOI: 10.1016/j.euromechflu.2025.204399

Nayab , Taqi Ahmad Cheema , Naveed Razzaq Butt , Atif Muzaffar , Rizwan Ullah

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.

重力涡系统（GVS）被定义为利用重力涡在无障碍物的盆地中进行能源产生和传热等应用的系统。这些盆地通常有两种类型：圆柱形和锥形。在给定的流动条件、流体性质和盆地的几何尺寸下，涡流上升到一定的高度，称为涡头，这是设计这些系统最关键的参数。然而，由于旋涡头预测工具的缺乏，往往导致水池设计不能形成适当的旋涡头，导致涡电厂溢流或涡轮淹没，或用于热交换器的涡池加热不均匀。传统的方法是通过调节流量来控制涡池中的涡头，但这种方法会损害涡的强度。为了解决这个问题，已经开发了一个基于流动条件、流体性质和盆地几何形状的经验框架来预测涡头。相关性包括四个无量纲数字：孔盆直径比（d/ d）、几何流量参数比、涡强度数（VN）和自由流湍流度（FST）。该模型的适用性仅限于没有内部障碍物的圆柱形和锥形盆地，直径比高达d/ d≤ 0.18，并且水作为唯一的工作流体。统计评价表明，该模型具有较高的准确性，决定系数（R2）为0.942，均方根误差（RMSE）为0.073，平均误差（MAE）为0.054。残差分析证实了预测的一致性和可靠性。该模型估计涡头在 ± 20 %的公差范围内，为实验室规模的设置和工业规模的重力涡应用提供了实用的设计工具。

{"title":"Development of a novel empirical correlation for vortex head in gravitational water vortex","authors":"Nayab , Taqi Ahmad Cheema , Naveed Razzaq Butt , Atif Muzaffar , 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<sub>N</sub>), 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 (R<sup>2</sup>) 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}

引用次数: 0

Dancing marbles in a soap film 在肥皂片里跳舞的弹珠

IF 2.5 3区工程技术 Q2 MECHANICS

European Journal of Mechanics B-fluids

Pub Date : 2026-03-01 Epub Date: 2025-11-20 DOI: 10.1016/j.euromechflu.2025.204423

Youna Louyer , Benjamin Dollet , Isabelle Cantat , Anaïs Gauthier

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.

两毫米大小的颗粒沉积在一个大的水平肥皂膜上，相互吸引。由于肥皂膜表面的摩擦力非常小，这些粒子可以呈现出复杂的轨迹，在碰撞前似乎会一起跳舞大约十秒钟。我们在这里对这个主题及其观点做一个简短的概述。

引用次数: 0

Effect of momentum flux ratio on the flow and combustion behavior of coaxial jets with annular blockage 动量通量比对环形阻塞同轴射流流动和燃烧特性的影响

IF 2.5 3区工程技术 Q2 MECHANICS

European Journal of Mechanics B-fluids

Pub Date : 2026-03-01 Epub Date: 2025-11-14 DOI: 10.1016/j.euromechflu.2025.204415

Shiferaw Regassa Jufar , Minh Duc Le

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.

用数值方法研究了带环形阻塞的同轴射流的流动和燃烧特性。用相关研究的实验结果对模型进行了验证。根据研究中提出的观察，确定了动量通量比变化时的两种主要流动形式。根据流场中旋涡结构和滞止点的性质，这些状态可以分为中心型和环状型两种。在动量通量比小于0.25时，中心射流占主导地位，内部混合区的夹带起关键作用。相反，在动量通量比大于2.5时，环形射流主导的流动通过在反向旋转的涡旋环内的流的再循环增强了混合。在燃烧过程中，动量通量比较低，由于没有停滞点和反向旋转的涡流环，导致火焰长度较长，导致混合性能较差。在较高的动量通量比下，反向旋转涡环和驻点的形成增强了混合，从而缩短了火焰长度，改善了燃烧性能。本研究的新颖之处在于基于环形和中心射流的雷诺数定义了特征流型，这有助于区分主要的流动模式。对于给定的射流雷诺数，可以识别主导模式，以优化混合和燃烧性能。

{"title":"Effect of momentum flux ratio on the flow and combustion behavior of coaxial jets with annular blockage","authors":"Shiferaw Regassa Jufar , 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}

引用次数: 0

Development of aeroacoustic control devices for a square cylinder using adjoint lattice Boltzmann method 用伴随晶格玻尔兹曼方法研制方形圆柱体气动声控制装置

IF 2.5 3区工程技术 Q2 MECHANICS

European Journal of Mechanics B-fluids

Pub Date : 2026-03-01 Epub Date: 2025-11-08 DOI: 10.1016/j.euromechflu.2025.204413

Kazuya Kusano

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.

气动噪声的控制在各个领域都是必不可少的，包括机械和航空航天工程应用，如高速列车和飞机起落架的受电弓。传统的装置，如分流板，长期以来一直被用来抑制尾流和由此产生的噪音；然而，超越这些经典设计的新型设备的开发尚未实现。本研究旨在利用结合晶格玻尔兹曼方法（LBM）和伴随方法的气动声学优化框架来开发创新的控制装置，以修改方形圆柱体的后表面。二维层流的雷诺数设为150，马赫数设为0.2。优化创造了一个山脊形状附近的后边缘。利用LBM进行的流动和声学分析表明，这种形状成功地抑制了尾流振荡，减轻了风成调的产生。此外，通过简化优化形状，提出了一种新的被动控制技术，即在方柱体后缘附近安装锥形分流板。LBM仿真结果表明，锥形分流板对方形圆柱尾流和流声的控制效果优于传统的直线分流板。

{"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}

引用次数: 0

Differential equation based wall distance approaches for maritime engineering flows 基于微分方程的船舶工程流壁距方法

IF 2.5 3区工程技术 Q2 MECHANICS

European Journal of Mechanics B-fluids

Pub Date : 2026-03-01 Epub Date: 2025-11-20 DOI: 10.1016/j.euromechflu.2025.204418

Niklas Kühl

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 p-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.

The validated models are applied to hydrodynamic and aerodynamic ship flows. For a model-scale bulk carrier (

R e_{L} = 7.2 \times 1 0^{6}

,

F n = 0.142

), 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 (

R e_{L} = 5.0 \times 1 0^{8}

) analyzed with a hybrid RANS/LES (IDDES) model exhibits greater sensitivity to wall-distance definitions.

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 p-Poisson and Screened-Poisson variants are more parameter-sensitive and computationally expensive.

本文研究了计算流体力学（CFD）中基于微分方程的壁距函数计算公式。壁距通过控制近壁阻尼函数和混合行为直接影响湍流建模，对于工业应用尤其重要，例如在涉及复杂船舶几何形状和流动配置的海事环境中。比较了几种方法，包括线性和非线性p-泊松方法、筛选-泊松方法、Eikonal方法、正则化Eikonal/ Hamilton-Jacobi方法和拉普拉斯方法。每个公式是离散和评估的数值稳定性，效率和精度对一个精确的几何基准。验证的模型应用于船舶的水动力和气动流动。对于模型级散货船（ReL=7.2×106, Fn=0.142），具有剪切应力输运（SST）湍流的reynolds - average Navier-Stokes （RANS）模拟表明，不同的壁距配方对阻力、纵倾和沉差的影响小于0.1%。一个时间上恒定的壁距场足以进行精确的推进预测。相比之下，使用混合RANS/LES （IDDES）模型分析的全尺寸支线船（ReL=5.0×108）对壁距定义表现出更大的敏感性。在测试的方法中，延迟校正的对流Eikonal或Hamilton-Jacobi公式在鲁棒性、计算成本和准确性之间取得了最佳折衷，而p-Poisson和Screened-Poisson变体对参数更敏感，计算成本更高。

{"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}

引用次数: 0

Lseq2seq: A new reduced-order model for unsteady aerodynamic force identification Lseq2seq：一种新的非定常气动力识别降阶模型

IF 2.5 3区工程技术 Q2 MECHANICS

European Journal of Mechanics B-fluids

Pub Date : 2026-01-01 Epub Date: 2025-09-24 DOI: 10.1016/j.euromechflu.2025.204377

Yihua Pan , Xiaomin An , Yuqi Lei , Xin Gao , Chen Ji

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.

在空气动力学中，非定常气动力的识别是一项重要而富有挑战性的任务。它也是其他学科如气动弹性、飞机设计和飞行动力学的重要研究基础。研究非定常气动力的两种主流方法是计算流体力学（CFD）和实验方法。然而，这些方法有其局限性，如计算费用长，资源消耗高。本文提出了一种基于深度序列生成模型的长序列到序列（Lseq2seq）降阶模型，以有效地预测非定常气动力。应用Lseq2seq模型确定了NACA0012翼型的滞回线和NACA64A010翼型在跨声速流动中两自由度振荡的非定常气动力。结果与其他流行的时间序列网络，如序列到序列（Seq2seq）和门控循环单元（GRU）进行了比较。提出的Lseq2seq模型具有更好的识别精度和泛化能力。此外，本文还对NACA64A010翼型颤振响应的预测校正组合方法GRU- lseq2seq进行了探索，结果表明，该组合模型比GRU模型具有更好的预测精度，可用于颤振边界预测。

{"title":"Lseq2seq: A new reduced-order model for unsteady aerodynamic force identification","authors":"Yihua Pan , Xiaomin An , Yuqi Lei , Xin Gao , 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}

引用次数: 0

Exact Riemann solutions for the drift-flux model of gas–liquid two-phase flows with van der Waals gas 范德华气气液两相流漂移通量模型的精确黎曼解

IF 2.5 3区工程技术 Q2 MECHANICS

European Journal of Mechanics B-fluids

Pub Date : 2026-01-01 Epub Date: 2025-10-06 DOI: 10.1016/j.euromechflu.2025.204383

Chunwang Yan , Yanyan Zhang , Yu Zhang

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.

建立了描述气液两相流动的范德华漂移通量模型，并对其黎曼问题进行了解析求解。采用统一的参数方法，导出了所有基本波的精确表达式，并严格地建立了解的存在唯一性。此外，我们提出了一个简单的标准，以确定是否冲击或稀疏波出现在1族和3族。最后，通过数值模拟验证了理论分析的正确性。本文对非理想气体漂移通量模型的Riemann问题进行了全面的分析，为研究非理想两相流动力学提供了一个精确的数学框架。

引用次数: 0

Impact of temperature dependent viscosity on thermo-bioconvective flow of Jeffrey fluid containing gravitactic microorganism in a permeable medium 温度依赖粘度对含重力微生物的Jeffrey流体在可渗透介质中热生物对流的影响

IF 2.5 3区工程技术 Q2 MECHANICS

European Journal of Mechanics B-fluids

Pub Date : 2026-01-01 Epub Date: 2025-10-09 DOI: 10.1016/j.euromechflu.2025.204386

Dhananjay Yadav , Houda Al Maqbali , Mukesh Kumar Awasthi , Ravi Ragoju , Saif Al Aghbari , Maryam Al Aameriya , Basama Al Hanai , Asma Al Malki , Ljina Al Aamri

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

R_{D, c}^{E x}

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

R_{B D}

, the bio Péclet number

P e_{B}

, the Jeffrey factor

γ

, and the viscosity deviation parameter

F

increase. In instances of exponential viscosity variation with temperature, the size of the convective cells grows with the viscosity deviation parameter

F

, 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.

本研究探讨了温度依赖性粘度的线性和指数变化如何影响存在于可渗透介质中的重力微生物的非牛顿杰弗里流体中热生物对流流动的启动，这在现有文献中尚未得到解决。考虑边界处不存在微生物通量，通过线性稳定性理论确定热生物对流的阈值，并利用伽辽金方法解析求解相应的特征值问题。结果表明，当粘度随温度呈线性变化时，系统开始对流的临界瑞利数rd，cEx比粘度随温度呈指数变化时高约11%。这表明，当粘度随温度呈指数变化时，与线性变化相比，系统更不稳定。随着生物瑞利-达西数rbd、生物psm - clet数peb、Jeffrey因子γ和粘度偏差参数f的增大，排列的稳定性降低。在粘度随温度呈指数变化的情况下，对流单元的尺寸随着粘度偏差参数f的增大而增大，而在粘度线性变化的情况下，对流单元的尺寸保持不变。此外，重要的是要强调振荡对流运动与当前的分析无关。

{"title":"Impact of temperature dependent viscosity on thermo-bioconvective flow of Jeffrey fluid containing gravitactic microorganism in a permeable medium","authors":"Dhananjay Yadav , Houda Al Maqbali , Mukesh Kumar Awasthi , Ravi Ragoju , Saif Al Aghbari , Maryam Al Aameriya , Basama Al Hanai , Asma Al Malki , 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}

引用次数: 0

Influences of particle-particle and particle-wall interactions on the settling behaviors of the centimeter-sized spherical particles 颗粒-颗粒和颗粒-壁相互作用对厘米级球形颗粒沉降行为的影响

IF 2.5 3区工程技术 Q2 MECHANICS

European Journal of Mechanics B-fluids

Pub Date : 2026-01-01 Epub Date: 2025-10-10 DOI: 10.1016/j.euromechflu.2025.204387

Lun Sun , Ri Zhang , Zhongwei Zhou , Jifu Yin , D.D. Meringolo

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 Gap. For individual particles released near the wall, when Gap 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, Gap 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.

本文通过实验研究了颗粒-颗粒和颗粒-壁相互作用对球形颗粒沉降过程的影响。采用会聚双目标定技术捕捉了三种典型条件下的沉降过程：(A)单个球形颗粒沉降在槽中心，(b)单个球形颗粒沉降在槽壁附近，(c)两个对称球形颗粒沉降在槽中心。初始颗粒-颗粒间隙或颗粒-壁间隙与颗粒直径之比定义为无量纲参数间隙。对于靠近壁面释放的单个颗粒，当间隙小于1.5时，壁面显著抑制了随机偏转特性，通常观察到单个球形颗粒沉降在罐中心。同样，对于两个对称粒子，随机偏转被明显抑制，具有高度对称的沉降速度和轨迹。靠近壁面的单个球形颗粒的沉降行为与对称对情况下面向壁面的颗粒的沉降行为非常相似，表明壁面有效地起着镜子的作用。此外，无论是在水箱壁面附近释放的单个颗粒还是在水箱中心释放的双颗粒，间隙对最终平均沉降速度的影响都很小。

{"title":"Influences of particle-particle and particle-wall interactions on the settling behaviors of the centimeter-sized spherical particles","authors":"Lun Sun , Ri Zhang , Zhongwei Zhou , Jifu Yin , 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}

引用次数: 0