{"title":"Evaluation of cabin noise of various subway systems","authors":"Hsiao Mun Lee \u0000 (, ), Heow Pueh Lee \u0000 (, )","doi":"10.1007/s10409-025-25015-x","DOIUrl":"10.1007/s10409-025-25015-x","url":null,"abstract":"<div><p>This study examines the variations in noise levels across various subway lines in Singapore and three other cities, and provides a detailed overview of the trends and factors influencing subway noise. Most of the equivalent sound pressure level (<i>L</i><sub>eq</sub>) in typical subway cabins across the Singapore subway lines are below 85 dBA, with some notable exceptions. These variations in noise levels are influenced by several factors, including rolling stock structure, track conditions and environmental and aerodynamic factors. The spectrogram analysis indicates that the cabin noise is mostly concentrated below the frequency of 1,000 Hz. This study also analyzes cabin noise in subway systems in Suzhou, Seoul, and Tokyo to allow for broader comparisons. It studies the impact of factors such as stock materials, track conditions including the quality of the rails, the presence of curves or irregularities, and maintenance frequency on cabin noise.\u0000</p><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":7109,"journal":{"name":"Acta Mechanica Sinica","volume":"41 7","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145161772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Turbulent evolution of liquid metal in an insulated duct under a non-uniform magnetic fields","authors":"Qi-Xian Hu \u0000 (, ), Long Chen \u0000 (, ), Ming-Jiu Ni \u0000 (, )","doi":"10.1007/s10409-025-25324-x","DOIUrl":"10.1007/s10409-025-25324-x","url":null,"abstract":"<div><p>Direct numerical simulations have been conducted to investigate the evolution process of liquid metal laminar to turbulent flow in a rectangular duct under the influence of a non-uniform magnetic field. The Reynolds number is <i>Re</i> = 6299, and the inlet Hartmann number is <i>Ha</i> = 2900, with the magnetic field strength decreasing along the flow direction. The results indicate that the dynamic reversal of the three-dimensional (3D) Lorentz force direction near the inflection point of the magnetic field dominates the flow reconstruction, driving the wall jet acceleration and forming an M-type velocity distribution. Moreover, the high-speed shear layer of the jet triggers Kelvin-Helmholtz instability, resulting in the generation of secondary vortex structures near the parallel layer in the non-uniform magnetic field region. In the cross-section perpendicular to the flow direction, the secondary flow gradually evolves into a four-vortex structure, while the velocity fluctuations and turbulent kinetic energy reach the peak. Based on the characteristics of the vortex rotation direction near the shear layer, the intrinsic mechanism behind the unique bimodal distribution of the root-mean-square of velocity fluctuations in the parallel layers is revealed. Furthermore, by comparing the evolution of turbulence under different magnetic field gradients, it is revealed that the distributions of shear stress, Reynolds stress, and turbulent kinetic energy exhibit significant parameter dependence. The strong 3D magnetohydrodynamic effects at the magnetic field gradient <i>γ</i> = 0.6 have an immediate impact on the pressure distribution. The transverse Lorentz force <i>LF</i><sub><i>z</i></sub> further promotes the fluid to accumulate at the wall, leading to a significant increase in the pressure drop and transverse pressure difference in the flow.</p></div>","PeriodicalId":7109,"journal":{"name":"Acta Mechanica Sinica","volume":"41 7","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145161771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Dynamics of an elliptical cylinder in confined Poiseuille flow under Navier slip boundary conditions","authors":"Xinwei Cai \u0000 (, ), Xuejin Li \u0000 (, ), Xin Bian \u0000 (, )","doi":"10.1007/s10409-025-25236-x","DOIUrl":"10.1007/s10409-025-25236-x","url":null,"abstract":"<div><p>A comprehensive understanding of surface wetting phenomena in microchannels is essential for optimizing particle transport and filtration processes. This study numerically investigates the dynamics of a freely suspended elliptical cylinder in confined Poiseuille flow, with a focus on Navier slip boundary conditions. The smoothed particle hydrodynamics method is employed, which is advantageous for its Lagrangian framework in handling dynamic fluid-solid interfaces with slip. Our results demonstrate that the slip conditions enable precise control over inertial focusing positions and particle motion modes. Compared to no-slip scenarios, unilateral wall slip induces two novel motion types: “leaning” and “rolling”. When equal slip lengths are applied to both walls, even small slip values facilitate off-center inertial focusing and elevate equilibrium positions. Slip on the cylinder surface further enhances inertial lift while suppressing rotational dynamics. In particular, under strong confinement or with large particle-surface slip lengths, we identify an additional distinct motion regime termed “inclined.” These findings provide new insights for active particle manipulation in microfluidic applications.</p></div>","PeriodicalId":7109,"journal":{"name":"Acta Mechanica Sinica","volume":"41 8","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145142538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xi-Qiao Feng (, ), Bo Li (, ), Shao-Zhen Lin (, ), Ming-Yue Wang (, ), Xin-Dong Chen (, ), Huan-Xin Zhang (, ), Wei Fang (, )
{"title":"Mechano-chemo-biological theory of cells and tissues: review and perspectives","authors":"Xi-Qiao Feng \u0000 (, ), Bo Li \u0000 (, ), Shao-Zhen Lin \u0000 (, ), Ming-Yue Wang \u0000 (, ), Xin-Dong Chen \u0000 (, ), Huan-Xin Zhang \u0000 (, ), Wei Fang \u0000 (, )","doi":"10.1007/s10409-025-25315-x","DOIUrl":"10.1007/s10409-025-25315-x","url":null,"abstract":"<div><p>Physiological and pathological processes such as embryonic development and tumor progression involve complicated interplay of mechanical, chemical, and biological factors cross a wealth of spatial and temporal scales. In this paper, we review some recent advances in the field of mechano-chemo-biological coupling theories in biological tissues and cells, and their applications in cancer, immunological, and other diseases. Key issues in the mechano-chemo-biological modeling of specific dynamic processes of cells and tissues are discussed. A mechano-chemo-biological growth theory is introduced, which interrogates the mechanical, chemical, and biological coupling mechanisms underpinning the growth, remodeling and degradation of tissues such as tumors. The mechano-chemo-biological instabilities of cells and tissues are systematically analyzed, with particular attention to those induced by coupled mechano-chemo-biological mechanisms. Furthermore, we provide a mechano-chemo-biological multiscale computational framework to investigate the dynamic processes of cells and tissues, for example, the migration and metastasis of cancer cells. Besides, we discuss some recent theoretical and experimental findings in the mechano-chemo-biological dynamics of collective cells. Finally, perspectives and clinical applications of the mechano-chemo-biological theories of cells and tissues are proposed.</p><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":7109,"journal":{"name":"Acta Mechanica Sinica","volume":"41 7","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145161370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Machine learning based constitutive modelling on craze yielding in polymeric materials","authors":"Keyi Jiang \u0000 (, ), Jici Wen \u0000 (, ), Yujie Wei \u0000 (, )","doi":"10.1007/s10409-025-25370-x","DOIUrl":"10.1007/s10409-025-25370-x","url":null,"abstract":"<div><p>The inelastic behavior of thermoplastic polymers may involve shearing and crazing, and both depend on temperature and strain rate. Traditional constitutive models account for temperature and strain rate through phenomenological or empirical formulas. In this study, we present a physics-guided machine learning (ML) framework to model shear and craze in polymeric materials. The effects of all three principal stresses for the craze initiation are considered other than the maximum tensile principal stress solely in previous works. We implemented a finite element framework through a user-defined material subroutine and applied the constitutive model to the deformation in three polymers (PLA 4060D, PLA 3051D, and HIPS). The result shows that our ML-based model can predict the stress-strain and volume-strain responses at different strain rates with high accuracy. Notably, the ML-based approach needs no assumptions about yield criteria or hardening laws. This work highlights the potential of hybrid physics-ML paradigms to overcome the trade-offs between model complexity and accuracy in polymer mechanics, paving the way for computationally efficient and generalizable constitutive models for thermoplastic materials.\u0000</p><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":7109,"journal":{"name":"Acta Mechanica Sinica","volume":"41 7","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145161372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jiaxin Rong (, ), Takahiro Shizukuda (, ), Hao Liu (, )
{"title":"Aeroacoustic investigation of owl-inspired hybrid trailing-edge serrations","authors":"Jiaxin Rong \u0000 (, ), Takahiro Shizukuda \u0000 (, ), Hao Liu \u0000 (, )","doi":"10.1007/s10409-025-25339-x","DOIUrl":"10.1007/s10409-025-25339-x","url":null,"abstract":"<div><p>Owls exhibit remarkably silent flight, largely attributed to trailing-edge (TE) serrations on their wings. Inspired by this biological adaptation, TE serrations have become promising passive-noise-control strategies for aerodynamic devices, including drones and wind turbines. However, conventional designs typically feature single-scale geometries—Such as sawtooth or sinusoidal serrations—that fail to replicate the owl’s inherently dual-scale morphology: Macro-scale waviness formed by feather tips combined with micro-scale morphology. Here, we introduce and evaluate a hybrid TE serration design that incorporates both macro-scale wave patterns and micro-scale fringe-like elements to closely emulate the owl wing structure. Using large-eddy simulations coupled with the Ffowcs Williams-Hawkings acoustic analogy, we assess three configurations: A smooth baseline, a conventional wavy serration, and the proposed hybrid serration. Our results indicate that the hybrid configuration achieves an overall noise reduction of about 12 dB relative to the smooth baseline, surpassing the conventional wavy configuration by approximately 2.5 dB, while preserving aerodynamic performance as measured by lift-to-drag ratio. Flow-field analyses further reveal that dual-scale serrations effectively suppress TE pressure fluctuations, highlighting a key aeroacoustic advantage of the owl-inspired hybrid approach. These insights advance our understanding of bioinspired noise-control mechanisms and provide practical guidelines for designing quieter aerodynamic systems.\u0000</p><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":7109,"journal":{"name":"Acta Mechanica Sinica","volume":"41 7","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145161371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yongze An (, ), Bo Wang (, ), Zhili Peng (, ), Xiaodong Chen (, ), Vigor Yang (, )
{"title":"Mechanistic insights and practical applications of impinging-jet dynamics and atomization","authors":"Yongze An \u0000 (, ), Bo Wang \u0000 (, ), Zhili Peng \u0000 (, ), Xiaodong Chen \u0000 (, ), Vigor Yang \u0000 (, )","doi":"10.1007/s10409-025-25469-x","DOIUrl":"10.1007/s10409-025-25469-x","url":null,"abstract":"<div><p>This review summarizes recent progress in the study of impinging-jet dynamics and atomization, with a focus on liquid sheet formation, instability mechanisms, and the influence of key parameters such as fluid properties, Weber number, and Reynolds number. Special attention is given to atomization behaviors under high pressure and external perturbations. Representative experimental and numerical approaches are introduced, and critical findings under complex conditions are highlighted. In addition, practical applications of impinging-jet technology in aerospace propulsion, biomedical devices, and energy science are discussed. This review aims to serve as a concise reference for researchers interested in multiphase flow dynamics and engineering applications of impinging jets.\u0000</p><div><figure><div><div><picture><img></picture></div></div></figure></div></div>","PeriodicalId":7109,"journal":{"name":"Acta Mechanica Sinica","volume":"41 7","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145161258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yan Gu (, ), Wenzhen Qu (, ), Bo Yu (, ), Chuanzeng Zhang (, ), Vladimir Babeshko
{"title":"A novel time-spectral BEM for efficient 2D dynamic analysis","authors":"Yan Gu \u0000 (, ), Wenzhen Qu \u0000 (, ), Bo Yu \u0000 (, ), Chuanzeng Zhang \u0000 (, ), Vladimir Babeshko","doi":"10.1007/s10409-025-25309-x","DOIUrl":"10.1007/s10409-025-25309-x","url":null,"abstract":"<div><p>This study presents a new boundary element method (BEM) framework for the numerical solution of general time-dependent or transient problems. By reformulating the time derivative as a domain integral, the framework effectively decouples the treatment of spatial and temporal variables, allowing for the independent application of specialized discretization methods. For the temporal domain, we introduce an innovative time-spectral integration technique, which is based on Gaussian-quadrature-based orthogonal polynomial expansions. This method not only achieves arbitrary orders of accuracy but also significantly enhances computational efficiency and stability, particularly for simulations involving rapid transients or long-time dynamic simulations. The domain integrals in the spatial domain are calculated using the scaled coordinate transformation BEM (SCT-BEM), a mathematically rigorous technique that converts domain integrals into equivalent boundary integrals, preserving the boundary-only discretization advantage inherent in BEM. Numerical experiments on transient heat conduction and dynamic wave propagation further demonstrate the framework’s performance and capabilities. These experiments show that the proposed framework outperforms traditional time-stepping BEM methods, particularly in terms of stability, convergence rates, and computational cost, making it a highly promising tool for practical engineering applications.</p><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":7109,"journal":{"name":"Acta Mechanica Sinica","volume":"41 7","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145170340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Topology optimization method for high-aspect-ratio wing considering geometric nonlinearity with bending and torsion controls","authors":"Longlong Song \u0000 (, ), Tong Gao \u0000 (, ), Weihong Zhang \u0000 (, )","doi":"10.1007/s10409-025-24113-x","DOIUrl":"10.1007/s10409-025-24113-x","url":null,"abstract":"<div><p>The high-aspect-ratio wing, which is widely utilized in aircraft to achieve superior aerodynamic efficiency, frequently experiences large deformations such as bending and torsion during its service life. This work focuses on the topology optimization of the high-aspect-ratio wing using multiple materials with bending and torsion controls considering geometric nonlinearity. A novel approach is proposed for achieving a spar-ribs material layout by independently controlling the directional maximum length scale of the void phase. The bending control based on the wing-tip nodal displacement and torsion control based on the deformation difference of the wing-tip nodes are proposed, respectively. Afterwards, the optimization formulations are given and the sensitivity analysis of the optimization responses is derived based on the increment of nodal displacement. The optimized results reveal that the spar-ribs structural layout is successfully attained through directional length scale control. Moreover, the optimized configurations with bending and torsion precisely controlled can be achieved. It also has been demonstrated that considering bending and torsion controls is highly profitable when assessing the trade-off between end compliance in wing optimization.</p><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":7109,"journal":{"name":"Acta Mechanica Sinica","volume":"42 4","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145170690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Baobei Li (, ), Guanghua Du (, ), Hu Zhang (, ), Jinlong Guo (, ), Wenjing Liu (, ), Can Zhao (, ), Ruqun Wu (, ), Wenchang Zhou (, ), Huijun Yao (, ), Hongjin Mou (, ), Cheng Shen (, ), Chenyu Li (, ), Muhammad Jahangeer, Linyan Fu (, )
{"title":"Bipolar nanofluidic channel: from rectifier to capacitor","authors":"Baobei Li \u0000 (, ), Guanghua Du \u0000 (, ), Hu Zhang \u0000 (, ), Jinlong Guo \u0000 (, ), Wenjing Liu \u0000 (, ), Can Zhao \u0000 (, ), Ruqun Wu \u0000 (, ), Wenchang Zhou \u0000 (, ), Huijun Yao \u0000 (, ), Hongjin Mou \u0000 (, ), Cheng Shen \u0000 (, ), Chenyu Li \u0000 (, ), Muhammad Jahangeer, Linyan Fu \u0000 (, )","doi":"10.1007/s10409-025-25161-x","DOIUrl":"10.1007/s10409-025-25161-x","url":null,"abstract":"<div><p>A systematic understanding of the mechanism in the rectification and capacitance of nanochannels and their regulation with the electrolyte concentration and electrical bias is pivotal for its wide applications to nanofluidic electronics, ion separation, energy storage, and molecule sensing. Single unipolar and bipolar cylindrical nanochannels through polymer film were fabricated using single ion bombardment and track etching. Cyclic voltammetry results show that the bipolar nanochannel switches from rectification to capacitance as the electrolyte concentration decreases. Electrochemical impedance spectroscopy revealed that the capacitive impedance fraction in the bipolar nanochannel is regulated by electrolyte concentration and voltage. The switch from rectification to capacitance in the polymer nanochannel is well explained through a fluidic <i>p</i>-<i>n</i> junction model with a variable ion depletion layer regulated by the applied bias voltage, which is supported by the multi-physics simulation using Poisson-Nernst-Planck and Navier-Stokes solution. This work provides a mechanistic insight into the ionic current rectification and ionic capacitance in complex ionic nanochannels and paves the way for biomimetic nanofluidic electronics design.</p><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":7109,"journal":{"name":"Acta Mechanica Sinica","volume":"41 8","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145144467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}