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A unidirectional phase-resolved wave prediction model based on deep Koopman embeddings 基于深库普曼嵌入的单向相位分辨波预测模型
IF 2.5 3区 工程技术 Q2 MECHANICS Pub Date : 2026-05-01 Epub Date: 2025-12-12 DOI: 10.1016/j.euromechflu.2025.204429
Zhongying Feng , Ye Wang , Chenghao Fu , Ruipeng Li , Kun Zheng , Zhan Wang
The phase-resolved wave prediction is of vital importance for improving the safety and operations of structures in ocean engineering, such as floating wind turbines and wave energy converters. However, it is challenging for traditional physical methods to predict wave elevation accurately and efficiently in high sea states where the nonlinearity plays an important role. Inspired by the capability of the Koopman theory in solving nonlinear problems, a phase-resolved wave prediction model by combining deep learning with Koopman operator, referred to as DKWP, is designed. The high-order spectral method is employed for providing training and test data. To illustrate the effectiveness of the proposed method, we compare it with another four phase-resolved wave prediction models, including the models based on artificial neural network, long short-term memory, U-Net and linear wave theory. The models are trained under the sea states 3–5 with wide ranges of significant height, peak period and peak factor. Comparisons between the predicted wave elevation and true wave elevation indicate that DKWP outperforms the other models in terms of accuracy. The generalization of the DKWP is validated when it predicts the wave elevation under the sea states 6–7. In addition, to improve the interpretability of the DKWP, the eigenvalues of the Koopman operator in the proposed model are further analyzed.
相分辨波浪预报对于提高海上工程结构的安全性和运行性能具有重要意义,如浮式风力发电机组和波浪能变流器。然而,在非线性起重要作用的高海况下,传统的物理方法难以准确有效地预测海浪高程。受Koopman理论解决非线性问题能力的启发,设计了一种结合深度学习和Koopman算子的相位分辨波预测模型,简称DKWP。采用高阶谱法提供训练和测试数据。为了说明该方法的有效性,我们将其与另外四种相位分辨波预测模型进行了比较,包括基于人工神经网络、长短期记忆、U-Net和线性波理论的模型。模型在3-5海况下进行训练,显著高度、峰值时段和峰值因子范围较大。预测波高与真实波高的比较表明,DKWP模型在精度上优于其他模型。通过对6 ~ 7海况下波浪高程的预测,验证了DKWP的泛化效果。此外,为了提高DKWP的可解释性,进一步分析了该模型中Koopman算子的特征值。
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引用次数: 0
Threshold of thermoconvective flows in a liquid metal battery with thermal coupling with its environment 液态金属电池与环境热耦合时的热对流阈值
IF 2.5 3区 工程技术 Q2 MECHANICS Pub Date : 2026-05-01 Epub Date: 2025-12-22 DOI: 10.1016/j.euromechflu.2025.204446
Anupam M. Hiremath , Harunori N. Yoshikawa , Innocent Mutabazi
Liquid Metal Battery (LMB) is a recent technology proposed to store the energy produced by intermittent sources such as solar cells, wind turbines or tidal power plants. The liquid metal batteries operate with large current densities but with very low open circuit voltages (OCV). A LMB consists of superimposed three layers of immiscible liquids in a stable stratification: the top layer made of light liquid metal and the bottom one made of dense liquid metal alloy sandwich the electrolyte layer (often a molten salt). Each layer has its own specific fluid properties and due to large difference in thermal and electrical conductivities between the liquid metals and the electrolyte, the application of a large current density can generate thermoconvective instabilities. The present works presents, in the framework of the linear stability analysis, the effects of the physical properties and thicknesses of liquid layers on the critical parameters on thermoconvective flows induced by Joule heating in a LMB of rectangular cross-section. The thermal coupling of the LMB with its environment described by the mixed thermal boundary conditions through the Biot number modifies the temperature profiles of the conduction state and reduces the threshold of all thermoconvective flows.
液态金属电池(LMB)是最近提出的一项技术,用于存储太阳能电池、风力涡轮机或潮汐发电厂等间歇性能源产生的能量。液态金属电池工作时电流密度大,但开路电压(OCV)很低。LMB由三层不混溶液体以稳定的分层叠加而成:顶层由轻液态金属制成,底层由高密度液态金属合金制成,夹在电解质层(通常是熔盐)中。每一层都有其特定的流体性质,由于液态金属和电解质之间的热导率和导电性差异很大,因此大电流密度的应用会产生热对流不稳定性。本文在线性稳定性分析的框架下,研究了矩形截面LMB中焦耳加热引起的热对流流动中,液体层的物理性质和厚度对临界参数的影响。混合热边界条件通过Biot数描述的LMB与环境的热耦合改变了传导态的温度分布,降低了所有热对流流的阈值。
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引用次数: 0
CFD-guided design and performance evaluation of a mobile aerator for delaying channel ice formation cfd导向的移动缓冰器设计与性能评价
IF 2.5 3区 工程技术 Q2 MECHANICS Pub Date : 2026-05-01 Epub Date: 2025-11-30 DOI: 10.1016/j.euromechflu.2025.204428
Fangpeng Zhao , Zhihong Li , Yang Chen , Wei Cui
Addressing the ice formation issue in open-channel water conveyance during winter in cold regions, this study guided the design of a mobile device integrating both propulsion and aeration functions. By enhancing water surface flow velocity and temperature distribution, the developed apparatus effectively delays the ice formation process and extends the normal water conveyance period. In this study, the CFD approach was conducted to investigate the hydrodynamic and thermal performance of the mobile aeration device in an open channel environment. The overset mesh method was applied to simulate the rotational motion of aeration components, while the Eulerian mixture model was used to capture the changes in the channel’s physical fields, including velocity and temperature distribution. Simulation results demonstrated that the device significantly improves flow characteristics and temperature distribution in the surface layer of open channels. Through systematic parametric analysis, the optimal combination scheme of key operational parameters (travel speed and longitudinal spacing) was determined, achieving enhanced flow velocity and temperature rise effects over extensive water areas.
针对寒冷地区冬季明渠输水结冰问题,本研究指导设计了集推进与曝气功能于一体的移动装置。该装置通过提高水面流速和温度分布,有效地延缓了冰的形成过程,延长了正常输水周期。在本研究中,采用CFD方法研究了移动曝气装置在开放通道环境下的水动力和热性能。采用复置网格法模拟曝气部件的旋转运动,采用欧拉混合模型捕捉通道物理场的变化,包括速度和温度分布。仿真结果表明,该装置显著改善了明渠表层的流动特性和温度分布。通过系统的参数分析,确定了关键运行参数(行程速度和纵向间距)的最优组合方案,在大面积水域实现了增强的流速和温升效果。
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引用次数: 0
Analysis of compliant tube properties and operating conditions in a Liebau pump 利宝泵柔性管特性及运行条件分析
IF 2.5 3区 工程技术 Q2 MECHANICS Pub Date : 2026-05-01 Epub Date: 2025-12-26 DOI: 10.1016/j.euromechflu.2025.204450
Manuel Rubio , Francisco Castro-Ruiz , José Sierra-Pallares , César Barrios-Collado , Joaquín Anatol
This study examines asymmetric pumping in Liebau pumps, a type of valveless pump that generates unidirectional flow through the periodic compression of a flexible (compliant) tube. This pumping has applications in biomedical devices, microfluidics, and organ support. We investigate how the properties of the compliant tube and the operating conditions affect the pump performance, using dimensionless parameters. Experiments were performed with different configurations, varying the tube material (latex and rubber) and the fluid (water and water–glycerine mixture). The results indicate that the flow rate and resonant period depend on the stiffness of the tube and the viscous effects. It was observed that for small values of the Womersley number (Wo2), viscous effects significantly reduce the flow rate. In contrast, for large Womersley values, the semiempirical models previously proposed adequately predict the experimental behaviour. Effects such as the compliant tube depression, which were not accounted for in previous models, were also found to influence performance. This work extends the analysis of this type of pump to unexplored conditions, with the aim of expanding knowledge and enabling the use of Liebau pumps in real-world applications.
本研究考察了Liebau泵中的不对称泵送,Liebau泵是一种无阀泵,通过对柔性(柔性)管的周期性压缩产生单向流动。这种泵送在生物医学设备、微流体和器官支持方面有应用。我们使用无量纲参数研究了弯曲管的特性和操作条件对泵性能的影响。实验以不同的结构进行,不同的管材料(乳胶和橡胶)和流体(水和水-甘油混合物)。结果表明,流量和共振周期取决于管道的刚度和粘性效应。观察到,当沃默斯利数(Wo2)较小时,粘性效应显著降低了流速。相比之下,对于较大的沃默斯利值,先前提出的半经验模型可以充分预测实验行为。在以前的模型中没有考虑到的弯曲管凹陷等影响也会影响性能。这项工作将这种类型的泵的分析扩展到未开发的条件,目的是扩大知识和在实际应用中使用Liebau泵。
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引用次数: 0
An analytical model for whirlwinds of finite width rising with bounded velocity and decaying outflow: Application to dust devils 有限宽度有界上升速度和衰减出口漩涡的解析模型:在尘卷风中的应用
IF 2.5 3区 工程技术 Q2 MECHANICS Pub Date : 2026-05-01 Epub Date: 2025-12-27 DOI: 10.1016/j.euromechflu.2025.204451
Sanjay Kumar Pandey, Kriti Yadav
This study presents an analytical model that extends previous formulations by incorporating axial dependence in all velocity components, thus offering a more realistic representation of dust devil dynamics. We address the limitations of the fundamental model of Vyas and Majdalani (2006), such as unbounded velocity and infinite vortex width, by modifying the stream function, which captures radial and axial variation of velocity. The velocity components are physically bounded and consistent with observed vortex structures. Additionally, the radial pressure distribution is derived, and the flow field is analysed using normalized radial, axial, and azimuthal velocities. The azimuthal velocity is computed from the radial and axial flows using the angular momentum equation. It increases from the centre, peaks near the periphery, and gradually decays to zero toward the axis. This model represents the compact features of dust devils by producing a smooth, confined structure with consistent vertical dependence, unlike alternative models that introduce abrupt transitions or unbounded behaviour. The profile maintains central stability in accordance with the Rayleigh criterion, while peripheral centrifugal instability reflects the transient and dissipative nature of dust devils. The model captures dust lifting and charge separation in dust devils, linking strong updrafts and confined flow to enhanced electrification and particle transport.
本研究提出了一个分析模型,通过在所有速度分量中纳入轴向依赖性,扩展了以前的公式,从而提供了一个更现实的尘暴动力学表示。我们通过修改流函数来解决Vyas和Majdalani(2006)的基本模型的局限性,例如无界速度和无限涡旋宽度,该流函数捕获了速度的径向和轴向变化。速度分量在物理上是有界的,与观测到的涡结构一致。此外,导出了径向压力分布,并使用归一化的径向、轴向和方位角速度分析了流场。用角动量方程从径向流和轴向流计算方位角速度。它从中心开始增加,在外围附近达到峰值,并逐渐向轴衰减到零。与引入突变或无界行为的其他模型不同,该模型通过产生具有一致垂直依赖性的光滑、受限结构来代表尘卷风的紧凑特征。剖面保持中心稳定符合瑞利准则,而外围离心不稳定反映了尘卷的瞬态和耗散性质。该模型捕获了尘卷中的粉尘提升和电荷分离,将强大的上升气流和受限流动与增强的电气化和粒子传输联系起来。
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引用次数: 0
Aerodynamic and aeroacoustic evaluation of slat and slot separation control on a small-scale HAWT: A computational study 小型HAWT狭缝分离控制的气动与气动声学评价:计算研究
IF 2.5 3区 工程技术 Q2 MECHANICS Pub Date : 2026-05-01 Epub Date: 2025-12-09 DOI: 10.1016/j.euromechflu.2025.204443
Sami Bouterra , Riyadh Belamadi , Abdelouaheb Djemili , Adrian Ilinca
The global push toward clean energy has intensified the search for efficient, innovative technologies to harness renewable resources. Small-scale horizontal-axis wind turbines (HAWTs) offer a promising solution to meet growing urban energy demands with minimal environmental impact. This computational study investigates the aerodynamic and aeroacoustic effects of two passive flow separation control techniques, slat and slot, applied to the blades of a small-scale HAWT. Using the NREL S809 Phase II rotor as a benchmark, simulations are conducted using the steady Moving Reference Frame (MRF) and the unsteady Sliding Mesh Motion (SMM) approaches. The k-ω SST turbulence model is validated against experimental data for multiple inflow conditions. The results demonstrate that flow separation is significantly mitigated by both control methods, particularly at higher wind speeds and at specific locations along the blade span. Quantitatively, the slat and slot configurations yield power output increases of 8.74 % and 21.07 %, respectively, compared to the baseline case. However, aeroacoustic analysis reveals that the slot introduces a sound pressure level (SPL) increase of up to 20 dB near 1 kHz, while providing a more balanced performance in terms of noise and energy gain. These findings highlight the slot configuration as a particularly effective solution for enhancing aerodynamic efficiency, while the slat provides a more balanced aeroacoustic profile. The choice between them involves a trade-off between maximum power gain and noise-control requirements in small-scale wind energy systems.
全球对清洁能源的推动加强了对利用可再生资源的高效、创新技术的探索。小型水平轴风力涡轮机(HAWTs)提供了一个有前途的解决方案,以满足日益增长的城市能源需求,同时对环境的影响最小。本文研究了窄缝和狭缝两种被动流动分离控制技术在小型HAWT叶片上的气动和气动声学效果。以NREL S809二期转子为基准,采用稳态移动参考系(MRF)和非定常滑动网格运动(SMM)方法进行了仿真。k-ω海温湍流模型在多种入流条件下进行了实验验证。结果表明,两种控制方法都显著减轻了流动分离,特别是在高风速和沿叶跨的特定位置。从数量上看,与基线情况相比,槽形和槽形配置的功率输出分别增加了8.74 %和21.07 %。然而,气动声学分析表明,该槽在1 kHz附近引入了高达20 dB的声压级(SPL)增加,同时在噪声和能量增益方面提供了更平衡的性能。这些发现强调了狭缝结构是提高气动效率的特别有效的解决方案,而狭缝提供了更平衡的气动声学剖面。在它们之间的选择涉及到在小型风能系统中最大功率增益和噪声控制要求之间的权衡。
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引用次数: 0
Macroscopic quantum-like behavior of a turbulent jet 湍流射流的宏观类量子行为
IF 2.5 3区 工程技术 Q2 MECHANICS Pub Date : 2026-05-01 Epub Date: 2025-11-29 DOI: 10.1016/j.euromechflu.2025.204427
Laurent Nottale, Thierry Lehner
We apply the scale-relativity theory of turbulence to round jets. For a flow reaching scales much larger than the integral scale, which is the case in jets, we find that fluid particle trajectories become fractal beyond the integral scale. On this basis, the Navier–Stokes equations can be integrated under the form of a macroscopic Schrödinger-type equation, which is solved in terms of a wave function whose modulus squared yields the concentration profile. The solution obtained is in excellent agreement with the experimentally observed turbulent free jet concentration. Then we have performed a new experiment, in order to put to the test such a macroquantum-like behavior. The free turbulent jet has a natural conic self-similar structure with opening angle αS0.235. We have performed an experiment consisting of confining a turbulent jet inside its own cone: this is, according to the scale-relativity approach, a macroscopic analog of a quantum particle in a cylindrical box. Thanks to the infinite potential well thus achieved, excited states can be reached. In the first one, we predict from the Schrödinger equation a vanishing concentration on the centerline of the jet, while it is highest for the free jet. This new theoretical prediction is validated with high statistical significance in our jet experiment, which therefore brings strong support to the existence of macroscopic quantum-like phenomena driven by (effective) nondifferentiability of a medium and its induced fractality.
我们将湍流的尺度相对论应用于圆形射流。对于比积分尺度大得多的流动,如射流,我们发现流体粒子轨迹在积分尺度之外就变成了分形。在此基础上,可以将Navier-Stokes方程积分为宏观Schrödinger-type方程,该方程用波函数求解,其模量平方得到浓度剖面。所得到的解与实验观察到的湍流自由射流浓度非常吻合。然后我们进行了一个新的实验,以测试这种类似大量子的行为。自由湍流射流具有自然锥型自相似结构,开口角αS≈0.235。我们进行了一项实验,将湍流射流限制在其自身的锥内:根据尺度相对论的方法,这是一个圆柱形盒子中量子粒子的宏观模拟。由于得到了无限的势能,就可以达到激发态。在第一种情况中,我们从Schrödinger方程预测射流中心线上的浓度会消失,而自由射流的浓度最高。这一新的理论预测在我们的射流实验中得到了高统计意义的验证,从而有力地支持了由介质的(有效)不可微性及其诱导分形驱动的宏观类量子现象的存在。
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引用次数: 0
Study on the dynamic evolution process of entrainment vortex at the horizontal inlet of a large low-head pump station 某大型低扬程泵站水平进口带涡动态演化过程研究
IF 2.5 3区 工程技术 Q2 MECHANICS Pub Date : 2026-05-01 Epub Date: 2025-11-26 DOI: 10.1016/j.euromechflu.2025.204426
Fusheng Lv, Pingping Li, Weihua Xiao, Luoping Pan
Understanding hydraulic transients during the inlet process of a pump station is crucial for identifying the adverse effects of strong turbulence on its operation. Such an understanding can enhance the overall quality of the pump system and mitigate potential risks associated with hydraulic transients. This paper investigates the formation mechanism of suction vortices in the forebay of a pumping station under high flow rates and their impact on the inflow regime through numerical simulation. By employing the coupled three-dimensional Volume of Fluid (VOF) + Level Set method, the dynamic evolution of the entrained flow vortex was calculated, and the causes and impacts of the vortex on the hydraulic characteristics of the pump station inlet were analyzed. The significant correlation between the development of entrained vortices and the excessive inflow angle caused by severe flow deviation in the forebay was elucidated. This study provides a visualization method for the spatiotemporal evolution of internal vortices at the horizontal inlet of large low-head pumping stations. It aids in identifying the causes of uneven flow and vibration in the inlet system, thus offering theoretical support for the safe operation of pumping stations.
了解泵站入口过程中的水力瞬变对于确定强湍流对泵站运行的不利影响至关重要。这样的理解可以提高泵系统的整体质量,降低与液压瞬变相关的潜在风险。本文通过数值模拟研究了大流量下泵站前湾吸涡的形成机理及其对入流流态的影响。采用耦合三维流体体积(VOF) + 水平集方法,计算了夹带流涡的动态演化过程,分析了夹带流涡产生的原因及其对泵站进口水力特性的影响。阐明了夹带涡的发展与前湾严重的流偏引起的过大入流角之间的显著相关性。本研究为大型低水头泵站水平进水口内涡的时空演变提供了一种可视化方法。有助于查明进水口系统流动不均匀和振动的原因,为泵站的安全运行提供理论支持。
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引用次数: 0
Impact of blood rheology on left heart haemodynamics: Newtonian vs. non-Newtonian modelling 血液流变学对左心血流动力学的影响:牛顿模型与非牛顿模型
IF 2.5 3区 工程技术 Q2 MECHANICS Pub Date : 2026-05-01 Epub Date: 2025-12-15 DOI: 10.1016/j.euromechflu.2025.204445
Valerio Lupi , Filippo Caruso Lombardi , Martino Andrea Scarpolini , Roberto Verzicco , Francesco Viola
Although blood exhibits non-Newtonian properties, it is often modelled as a Newtonian fluid in numerical studies. However, the impact of this assumption on the accuracy of the predictions of computational models is not thoroughly assessed. For this reason, in this work, we compare the effect of Newtonian and shear-thinning blood rheological models on computational haemodynamics in the left heart. The analysis is based on the fluid–structure-electrophysiology interaction (FSEI) within a patient-specific anatomy of an individual with low ejection fraction to better highlight viscosity changes at low strain rates. Owing to the pulsatile nature of the flow, considerable spatio-temporal variations of the kinematic viscosity are observed for the non-Newtonian case. Integral quantities as well as blood pressure within the cardiac chambers are found to be weakly affected by the rheological model. Substantial differences are reported, instead, between the Newtonian and non-Newtonian cases, for the wall shear stress and local haemolysis index since they are sensitive to the local kinematic viscosity, which decreases within the shear layers of the systolic and diastolic jets, as well as in the near-wall regions.
虽然血液表现出非牛顿流体的特性,但在数值研究中它通常被建模为牛顿流体。然而,这一假设对计算模型预测准确性的影响并没有得到彻底的评估。因此,在这项工作中,我们比较了牛顿和剪切稀释血液流变学模型对左心计算血流动力学的影响。该分析基于低射血分数个体的特定解剖结构中的流体结构-电生理相互作用(FSEI),以更好地突出低应变速率下的粘度变化。由于流动的脉动性质,在非牛顿情况下观察到相当大的运动粘度的时空变化。研究发现,流变模型对心脏腔内的积分量和血压影响不大。相反,在牛顿和非牛顿的情况下,壁面剪切应力和局部溶血指数有实质性的差异,因为它们对局部运动粘度很敏感,在收缩和舒张射流的剪切层内,以及在近壁区域,运动粘度降低。
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引用次数: 0
Electron acoustic solitary wave in quantum plasmas with Kappa electrons 具有Kappa电子的量子等离子体中的电子声孤波
IF 2.5 3区 工程技术 Q2 MECHANICS Pub Date : 2026-05-01 Epub Date: 2025-12-23 DOI: 10.1016/j.euromechflu.2025.204449
Aakanksha Singh, Punit Kumar
Electron-acoustic solitary waves (EASWs) in quantum plasma comprising stationary ions, cold electrons, hot electrons, and kappa-distributed electrons have been investigated. The generalized Kappa-Fermi distribution has been modified to include electrostatic energy contribution and the number density of Kappa electrons has been obtained using this modified distribution. Utilizing the quantum hydrodynamic (QHD) model, a dispersion relation has been derived for linear EAWs. Employing the standard reductive perturbation technique, a Korteweg–de Vries (KdV) equation governing the dynamics of EAWs have been derived. The quantum mechanical effects of different parameters like kappa index, Mach number and equilibrium kappa electron density have been examined on the profiles of EASWs. It is found that the presence of kappa electrons in quantum plasma leads to new results, including steeper dispersion curves, sharper and more localized solitary waves with lower value of kappa index and stronger plasma interactions with increased kappa electrons density in dense astrophysical environment.
研究了由固定离子、冷电子、热电子和kappa分布电子组成的量子等离子体中的电子声孤波。对广义Kappa- fermi分布进行了修正,使其包含静电能量的贡献,并由此得到了Kappa电子的数密度。利用量子流体力学(QHD)模型,推导了线性ews的色散关系。采用标准的约化微扰技术,推导了一个控制电畴动力学的KdV方程。考察了kappa指数、马赫数和平衡kappa电子密度等参数对EASWs谱线的量子力学效应。研究发现,在致密的天体物理环境中,量子等离子体中kappa电子的存在导致了新的结果,包括色散曲线更陡,kappa指数更低,孤立波更尖锐,更局域化,kappa电子密度增加,等离子体相互作用更强。
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引用次数: 0
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European Journal of Mechanics B-fluids
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