期刊文献+
任意字段
题名或关键词
题名
关键词
摘要
作者
第一作者
机构
刊名
分类号
参考文献
作者简介
基金资助
栏目信息
共找到6,815篇文章
< 1 2 … 250 >
每页显示 20 50 100
已选0条
引用分析
参考文献
引证文献
 统计分析
检索结果
已选文献
显示方式：
Impact of wall oscillation on the drag and flow structure in an open channel at transitional Reynolds number 认领 引用 被引量：1
1
作者 Bofu Wang Luyao Zhang +1 位作者 Jianghua Li Quan Zhou 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2026年第5期187-198,共12页
This study investigates the effects of spanwise wall oscillations(SWOs)on open channel flow at Reτ=85 using direct numerical simulations.The oscillation amplitude is fixed at A+=12,and the period T+varies from ... This study investigates the effects of spanwise wall oscillations(SWOs)on open channel flow at Reτ=85 using direct numerical simulations.The oscillation amplitude is fixed at A+=12,and the period T+varies from 20 to 400.Results show that SWOs reduce drag,with the highest reduction of 31%at T+=70.The primary mechanisms include an elevated streamwise velocity profile,reduced Reynolds stress,and disruption of near-wall coherent structures.A novel vortex cluster structure emerges,weakening near-wall streaks and reducing skin friction drag.As T+increases,the spanwise tilt of near-wall streaks becomes more pronounced,and turbulence recovers,leading to drag values closer to the uncontrolled flow.Beyond T+=70,the modulation effect on turbulence fluctuations saturates.SWOs mainly regulate Reynolds shear stress by controlling Q4 events,with shorter periods suppressing large-scale structures and longer periods enhancing velocity fluctuations. 展开更多
关键词 Transitional Reynolds number Drag reduction Turbulent structures
暂未订购 下载PDF
Building Drag Parameterization Including Anisotropy and Its Coupling with the Weather Research and Forecasting Model 认领 引用
2
作者 Yuhang TIAN Zhenghui XIE +7 位作者 Jinbo XIE Binghao JIA Shuai SUN Peihua QIN Ruichao LI Longhuan WANG Heng YAN Yanbin YOU 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2026年第7期1461-1477,共17页
Buildings increase the urban surface roughness and reduce near-surface wind speeds due to the drag effect,which depends on the flow direction.In this study,a building drag parameterization scheme including the buildin... Buildings increase the urban surface roughness and reduce near-surface wind speeds due to the drag effect,which depends on the flow direction.In this study,a building drag parameterization scheme including the building anisotropy for all flow directions was developed through approximating buildings with elliptical columns to represent anisotropic frontal area index.The new scheme was coupled with the Weather Research and Forecasting(WRF)model to improve urban simulations in those including near-surface wind speeds.The conducted offline sensitivity tests with the developed scheme,using horizontal wind along different directions,show continuous transitions of drag coefficient and other variables depending on flow direction.The maximum difference of drag coefficient between the new and the original scheme reached 10%–20%of that from the original one.These monthly simulations of the WRF model with the new building drag scheme for Chengdu were conducted to validate the updated model against station observation and reanalysis data.Compared to the original scheme,the updated scheme reduces overestimation of 10-m wind speed by 0.1–0.2 m s−1(5%–15%of the original bias),overestimation of 2-m temperature by 0.1℃–0.4℃(20%–60%),and underestimation of 2-m relative humidity by 1%–3%(20%–60%).This is achieved by increasing the drag coefficient through an enhanced frontal area index and reducing wind speed.The diminished wind speed reduces sensible heat flux,enhances latent heat flux,and suppresses vertical motions,resulting in humidity accumulation and cooling in the lower atmosphere.These suggest that reasonable representation of the building anisotropy is important in researching urban climate. 展开更多
关键词 building drag parameterization frontal area index building anisotropy urban canopy model Weather Research and Forecasting model
暂未订购 下载PDF
Experimental investigation on the drag reduction performance by periodically slow-releasing polymer solution through porous media 认领 引用 被引量：2
3
作者 Hao Liu Hai-Bao Hu +4 位作者 Hai-Hua Deng Yong-Feng Yu Biao Huang Jun Wen Luo Xie 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2026年第5期149-168,共20页
In practical engineering applications of polymer drag reduction(DR),the environment is often complex and dynamic.Factors such as water depth and flow velocity could interfere with the constant polymer releasing state,... In practical engineering applications of polymer drag reduction(DR),the environment is often complex and dynamic.Factors such as water depth and flow velocity could interfere with the constant polymer releasing state,resulting in the occurrence of fluctuation in the polymer releasing process.An experimental study was conducted to evaluate the polymer DR performance when periodically released into turbulent channel flow in square and triangular waveform patterns.The polymer diffusion and the velocity profile were obtained using particle image velocimetry and planar laser-induced fluorescence measurements to further analyze the DR mechanism.For the square wave pattern with abrupt changes within a period,the existing rising and declining phases in DR and near-wall polymer concentration curves as a function of time always resulted in poor tracking performance.Although increasing the slow-release period shifted the peak point towards a plateau stage and elevated the peak DR,the gradual decline in trough DR and the extended duration of the decline still weakened the average DR efficiency over one period.In other words,the DR effects became increasingly weaker compared to those achieved by continuously releasing methods due to the extended period of ineffectiveness.Increasing the slow-release rate and the duty cycle could improve the average DR efficiency,but this was still inferior to the continuously releasing method because of the aforementioned poor tracking performance.Conversely,the DR and near-wall polymer concentration curves exhibited significant tracking performance in response to the triangular wave pattern with gradual change characteristics.Increasing the period enlarged and then stabilized the peak DR,while diminishing and stabilizing the trough DR.Thus,the average DR effect remained unchanged,and always comparable to the continuously releasing method.Increasing the slow-release rate promoted and then stabilized both the peak and trough DRs.The increasing trend of the overall DR efficiency versus slow-release rate nearly overlapped with that achieved by the continuously releasing method.This indicated that releasing polymer by triangular waves could not only provide equivalent DR to the continuously slow-release method but also offer greater environmental robustness.It is conjectured that other gradient wave patterns for periodically releasing polymer solution may also result in improved DR performance,potentially surpassing the efficiency of the continuous releasing method.This study offers valuable insights into optimizing polymer release strategies for the purpose of enhancing DR in external flows. 展开更多
关键词 Polymer drag reduction Periodically slow-release Turbulent channel flow
暂未订购 下载PDF
Improved drag reduction properties of biomimetic surface with cross-scale arrayed structures based on a comparative simulation study 认领 引用
4
作者 Shizheng Chen Zhuonan Liu +4 位作者 Peiquan Yu Weihao Wan Qing Zhao Jialin Li Xiaoping Huang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2026年第2期128-136,共9页
Current drag reduction research predominantly focuses on micro-scale surface modifications inspired by sharkskin or riblet textures,often overlooking the synergistic effect of macro-and micro-scale structures.This stu... Current drag reduction research predominantly focuses on micro-scale surface modifications inspired by sharkskin or riblet textures,often overlooking the synergistic effect of macro-and micro-scale structures.This study proposes a cross-scale biomimetic fish scale array structure designed based on fluid-structure interaction principles.A three-dimensional laminar flow simulation using COMSOL Multiphysics was conducted to evaluate the drag reduction performance.The model incorporates a tiled array of fan-shaped fish scales with embedded parallel microchannels,simulating gas-liquid-solid interaction in a low-speed water environment.A systematic parametric optimization was performed,involving aspect ratio,edge curvature radius,microchannel depth and spacing,edge height,and gas fraction.The optimal configuration—aspect ratio of 150 %,curvature radius of150 mm,microchannel period of 0.2 mm,duty cycle of 80%,and semi-circular cross-section—achieved up to20 % reduction in drag compared to a smooth surface under 2 m/s laminar flow.Further simulations show that drag reduction decreases with increasing immersion depth but stabilizes around 20% beyond 10 m.Flow visualization revealed that clockwise vortices form in the posterior edge of the fish scale,modifying the boundary layer and promoting slip flow,acting similarly to rolling bearings that reduce surface friction.Moreover,directional flow tests demonstrated that forward flow along the scale arrangement results in significantly higher drag reduction than perpendicular or reverse directions.These findings indicate that combining macro-scale geometry with microchannel-induced slip flow can effectively reduce resistance and promote energy efficiency in underwater applications.The study introduces an effective,scalable drag-reducing surface that bridges microstructure benefits with macro-scale flow-altering geometry,offering a novel approach for the design of energy-saving marine coatings and pipeline linings. 展开更多
关键词 Drag reduction Biomimetic surface Cross-scale structure Laminar flow simulation
暂未订购 下载PDF
Drag reduction and vortex evolution mechanisms of single-hole micro-blowing in a supersonic turbulent boundary layer 认领 引用
5
作者 Pujun ZHAO Xiaoshuai WU Yuxin ZHAO 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2026年第4期178-200,共23页
Micro-blowing techniques have shown significant potential for friction drag reduction in supersonic turbulent boundary layers,yet the pore-scale interaction mechanisms remain poorly understood.This study employs Direc... Micro-blowing techniques have shown significant potential for friction drag reduction in supersonic turbulent boundary layers,yet the pore-scale interaction mechanisms remain poorly understood.This study employs Direct Numerical Simulation(DNS)to investigate the fundamental physics of single-hole micro-blowing in a supersonic turbulent boundary layer.The results reveal a dual-regime drag reduction mechanism for the single-hole micro-blowing system:upstream reduction driven by adverse pressure gradients and downstream reduction dominated by mean convection effects.Micro-blowing establishes a three-layer shear interaction system(“wall-air film-mainstream”)downstream through the formation of a low-speed air film,which effectively reduces near-wall skin friction and turbulent fluctuation intensity.The study identifies two key vortex-mediated mechanisms:the generation of a counter-rotating streamwise vortex pair that forms vorticity sheets in the near-wall region,and their sign-dependent interactions with turbulent induced vorticity sheets(intensification for samesign interactions and weakening for opposite-sign cases).The micro-blowing induced vorticity sheet serves as a near-wall barrier,reducing both the frequency and intensity of“turbulent vortex-wall”interactions.Additionally,the low-speed sweep flow induced by micro-blowing streamwise vortices contributes to skin friction reduction.A key finding is the remarkable stability of drag reduction under turbulent vortex interference─the micro-blowing system maintains its baseline performance when interacting with turbulent streamwise vortices,demonstrating robustness for practical applications. 展开更多
关键词 Direct numerical simulation Drag reduction Micro-blowing Turbulent boundary layer Vortex evolution
暂未订购 下载PDF
Wheel Flow Instabilities and Drag Control in Automotive Aerodynamics:A Comprehensive Review 认领 引用
6
作者 Heming Xu Haichao Zhou +2 位作者 Wei Zhang Wenxuan He Lin Bo 《Fluid Dynamics & Materials Processing》 EI 2026年第3期1-17,共17页
This review addresses four key themes in automotive aerodynamics:flow instability in the wheel region,the aerodynamic characteristics of rims,the aerodynamic behavior of tires,and drag reduction strategies based on fl... This review addresses four key themes in automotive aerodynamics:flow instability in the wheel region,the aerodynamic characteristics of rims,the aerodynamic behavior of tires,and drag reduction strategies based on flow control around the wheels.The wheel region,comprising the tire,rim,and adjacent aerodynamic components,typically represents the major source of vehicle drag owing to the inherently complex flow generated by wheel rotation,tread geometry,and rim design,which gives rise to flow separation,vortex shedding,and turbulence.Drawing on a broad body of experimental and numerical research,this review elucidates the mechanisms governing such dynamics,and considers drag mitigation techniques,including biomimetic surface treatments and multi-element flow control concepts.Particular emphasis is placed on enclosed-spoke rims,rim-edge enclosures,and non-smooth tire microstructures,which have consistently demonstrated notable drag reduction potential.The review further identifies critical shortcomings in current research,most notably the lack of quantitative analyses of aerodynamic energy losses and the absence of integrated optimization strategies that jointly address tire,rim,and fender design. 展开更多
关键词 Wheel region flow instability aerodynamic characteristics drag reduction methods
暂未订购 下载PDF
An Overview of Drag Reduction Methods in Road Cars 认领 引用
7
作者 Umberto Ravelli Silvia Ravelli 《Fluid Dynamics & Materials Processing》 EI 2026年第2期1-41,共41页
Aerodynamic research on road cars was reviewed in this work under the thread of reducing drag,with the awareness that this may succeed in effectively decreasing the carbon footprint of transportation.First,a selection... Aerodynamic research on road cars was reviewed in this work under the thread of reducing drag,with the awareness that this may succeed in effectively decreasing the carbon footprint of transportation.First,a selection of studies was presented to focus on the most important aerodynamic features of the flow around realistic car body shapes.Then,the discussion was organized around three pillars related to passive flow control,active flow control and active aerodynamics.Both experimental and numerical investigations were included to provide a comprehensive overview.A clear distinction was made between simplified and realistic car models,as well as production vehicles(within the limits of restricted access information).Moreover,a short essay was dedicated to electric vehicles,for which aerodynamics matters,especially at highway speeds.Last,the impact of aerodynamic principles on the design of current and future vehicle fleet was assessed,honestly admitting that recent market trends must be reversed to turn decarbonization goals into reality and damp the effects of global warming. 展开更多
关键词 Road cars aerodynamics drag coefficient passive flowcontrol active flowcontrol active aerodynamics
暂未订购 下载PDF
An adaptive lattice Boltzmann method for wake effect on drag force of interactive particles in supercritical water 认领 引用
8
作者 Xue Qiao Hui Jin +1 位作者 Haozhe Su Liejin Guo 《Particuology》 SCIE EI CAS CSCD 2026年第8期68-77,共10页
Supercritical water gasification(SCWG)is a highly promising technology.A fundamental aspect of SCWG in-volves the flow of supercritical water(SCW)around interactive particles,which is inherently complex due to the pre... Supercritical water gasification(SCWG)is a highly promising technology.A fundamental aspect of SCWG in-volves the flow of supercritical water(SCW)around interactive particles,which is inherently complex due to the presence of the wake effect.This study numerically investigates particle wake characteristics and wake-particle interactions in high-viscosity supercritical water(SCW)via an adaptive lattice Boltzmann method(LBM,N/D=30,coarse-fine ratio 0.025:0.060)to support supercritical water gasification(SCWG)reactor optimization.The adaptive LBM effectively balances accuracy and efficiency,resolving SCW's steep viscosity gradients and fine wake structures well.Interparticle distance(L/D)is the dominant factor for particle drag,affecting trailing particles far more significantly,with three interaction regimes(strong:L/D=0-2,moderate:2-4,weak:≥4).SCW's high viscosity amplifies wake overlap at L/D≤2,minimizing trailing particle pressure drag and sup-pressing vortex shedding;increasing L/D weakens shielding,elevates drag,and makes trailing particles behave like isolated ones.Interparticle angle raises drag ratios,inducing distinct vortex structures at 30°-60°and 60°-90°,with identical drag at 90°.SCW wake symmetry and vortex shedding show Re-dependent transitions,with critical Re=92 corresponding to the minimum trailing particle drag ratio.A drag ratio correlation with L/D and Re is also established.This work provides a reliable numerical tool for SCW particle interactions and theoretical guidance for SCWG reactor optimization,with future work focusing on particle swarms and exper-imental validation. 展开更多
关键词 Lattice Boltzmann method Boussinesq approximation Wake effect Drag force Numerical simulation
Negative Coulomb drag between graphene quantum Hall edges 认领 引用
9
作者 SONG Junwei GAN Qikang +4 位作者 ZHU Wang WATANABE Kenji TANIGUCHI Takashi YU Geliang WANG Lei 《物理学进展》 北大核心 2026年第1期1-12,共12页
Coulomb drag refers to the phenomenon in which a current driven through one conducting layer induces a voltage nearby,electrically isolated layer sorely through interlayer Coulomb interactions between charge carriers.... Coulomb drag refers to the phenomenon in which a current driven through one conducting layer induces a voltage nearby,electrically isolated layer sorely through interlayer Coulomb interactions between charge carriers.It has been extensively studied in various systems,including parallel nanowires,double quantum wells,and double-layer graphene.Here,we report the observation of Coulomb drag in a novel system consisting of two graphene layers separated laterally by a 30 nm gap within the material plane,exhibiting behavior distinct from that in vertical graphene heterostructures.Our experiments reveal pronounced negative drag resistances under an out-of-plane magnetic field at the quantum Hall edges,reaching a maximum when the carrier densities in both graphene layers are tuned to the charge neutrality point via gate voltages.Our work establish two separate and spatially closed quantum Hall edge modes as a new platform to explore electronic interaction physics between one dimensional systems. 展开更多
关键词 negative Coulomb drag quantum Hall edges van der Waals heterostructures
暂未订购 下载PDF
Drag and lift on two-dimensional super-elliptical particles in low-Reynolds-number flows 认领 引用
10
作者 Qinghua Li Zhenyu Ouyang Xiaoke Ku 《Particuology》 SCIE EI CAS CSCD 2026年第5期247-259,共13页
This study investigates the hydrodynamic forces acting on two-dimensional super-elliptical particles in low-Reynolds-number flows using the lattice Boltzmann method.The effects of particle aspect ratio,shape factor,an... This study investigates the hydrodynamic forces acting on two-dimensional super-elliptical particles in low-Reynolds-number flows using the lattice Boltzmann method.The effects of particle aspect ratio,shape factor,angle of attack,and particle Reynolds number on the drag and lift coefficients are systematically analyzed.The drag and lift coefficients averaged over the angle of attack are defined as the mean drag coefficient and mean lift coefficient,respectively.The results reveal that the mean drag coefficient increases with increasing aspect ratio and decreasing shape factor and particle Reynolds number,and the variation trends of the mean lift coefficient are generally consistent with those of the mean drag coefficient.Moreover,the shape of the drag coefficient-angle of attack curve is primarily governed by the shape factor and aspect ratio,leading to five distinct curve types.In contrast,the shape of the lift coefficient-angle of attack curve is also influenced by the particle Reynolds number,resulting in four curve types.In total,seven representative functional forms for the drag and lift co-efficients are identified and fitted,offering correlations for future applications. 展开更多
关键词 Super-elliptical particles Drag coefficient Lift coefficient Low-Reynolds-number flow
Development of the drag model for distillation columns under heterogeneous flow regime via direct numerical simulation 认领 引用
11
作者 Zhendong Li Xieyu He +2 位作者 Xiao Chen Zheqing Huang Qiang Zhou 《Particuology》 SCIE EI CAS CSCD 2026年第5期111-122,共12页
An accurate gas-liquid drag model is crucial for simulating bubble swarms in distillation columns.Under typical industrial operating conditions,distillation columns predominantly operate in the heterogeneous flow regi... An accurate gas-liquid drag model is crucial for simulating bubble swarms in distillation columns.Under typical industrial operating conditions,distillation columns predominantly operate in the heterogeneous flow regime.To obtain reliable data under this regime,this study employs direct numerical simulation to conduct high-resolution simulations of bubble swarm dynamics at high superficial gas velocities.The drag force on the bubble swarm is calculated accurately based on the direct integration of stresses on bubble surfaces.Given the substantial dif-ferences in flow regimes—homogeneous,transition,and heterogeneous—under varying superficial gas veloc-ities,this study develops not only an overall drag model spanning gas holdups from 0.1 to 0.6,but also a piecewise model based on flow regime characteristics.Both models describe the bubble swarm correction factor in terms of both gas holdup and Reynolds number,where the Reynolds number captures the evolution of the flow state.A posteriori validation using a two-fluid model demonstrates that,compared to other drag models,both proposed models significantly improve the prediction accuracy of the clear liquid height,particularly at the high superficial gas velocity.The piecewise model performs optimally,achieving a mean relative error of only 10.39%and 12.66%relative to experimental data. 展开更多
关键词 Distillation columns Drag model Direct numerical simulation Heterogeneous Computational fluid dynamics
Co-firing in pulverized coal boilers:Drag coefficient models and lateral drift of wheat straw fragments 认领 引用
12
作者 Haoteng Zhang Xuying Lu +4 位作者 Bingyi Jiang Cuina Qin Lihui Yu Shuo Jiang Chunjiang Yu 《Particuology》 SCIE EI CAS CSCD 2026年第5期36-51,共16页
For flexible and hollow straw-like biomass,direct co-firing via preliminary crushing and pneumatic conveying represents a promising technological pathway.However,this approach faces two major challenges:the lack of ac... For flexible and hollow straw-like biomass,direct co-firing via preliminary crushing and pneumatic conveying represents a promising technological pathway.However,this approach faces two major challenges:the lack of accurate drag coefficient models for non-spherical,centimeter-sized straw fragments during pneumatic transport and furnace flow,and the risk of lateral drift that may cause deposition during conveying or deviation from the combustion zone.To address these issues,this study establishes dedicated drag coefficient models for rectangular platelets,circular tubes,and solid cylinders,representing typical shapes of straw fragments.These models provide essential parameters for characterizing gas-solid flow in both conveying and combustion processes.Through combined experimental and numerical simulations,the lateral drift mechanism of non-spherical par-ticles was investigated.Results indicate that lateral translation and rotation originate from the non-uniform distribution of fluid drag along the windward surface,generating horizontal force components and torque.Based on experimental and theoretical analysis,it is proposed that high-velocity dilute-phase pneumatic conveying,distinct from pulverized coal transport,should be adopted to mitigate deposition and blockage risks during straw fragment transport.Meanwhile,the risk of unburned carbon loss due to straw fragments leaving the combustion zone was ruled out.This work provides a practical drag coefficient model for co-firing applications,preliminarily clarifies the mechanism of lateral drift,and offers crucial engineering guidance for the preliminary crushing and pneumatic conveying process of straw-based biomass. 展开更多
关键词 Pulverized coal boiler Straw fragments Drag coefficient Lateral drift
Giant Drag Fluctuations in Graphene-Based Electronic Double-Layer Systems 认领 引用
13
作者 Chi Zhang Lijun Zhu +1 位作者 Lin Li Changgan Zeng 《Chinese Physics Letters》 SCIE EI CAS CSCD 2025年第11期271-292,共22页
Recent advances in two-dimensional layered systems have greatly enriched electronic transport studies, particularly in inter-layer Coulomb drag research. Here, systematic transport measurements were conducted in graph... Recent advances in two-dimensional layered systems have greatly enriched electronic transport studies, particularly in inter-layer Coulomb drag research. Here, systematic transport measurements were conducted in graphene-based electronic double-layer structures, revealing giant yet reproducible drag fluctuations at cryogenic temperatures. These fluctuations' characteristics, including amplitude and peak/valley spacing, are mainly determined by the drag layer's carrier dynamics rather than the drive layer's, resulting in violation of the Onsager reciprocity relation. Notably, the drag fluctuations remain observable up to 35 K, far exceeding universal conductance fluctuations within individual layers. This suggests enhanced phase coherence in inter-layer drag compared to single-layer transport, as further confirmed by quantitative analysis of auto-correlation fields of fluctuations under magnetic fields. Our findings provide new insights into quantum interference effects and their interplay with Coulomb interactions in solids. The observations of significant drag fluctuations could potentially help address chaotic signals between nearby components in nanoscale devices. 展开更多
关键词 giant drag fluctuations electronic transport studies graphene based electronic double layer systems drive layers drag fluctuations drag layers carrier dynamics cryogenic temperatures systematic transport measurements
暂未订购 下载PDF
Bionic Pit-structured Warp-knitted Fabrics for Drag Reduction in Competitive Swimwear 认领 引用
14
作者 Jiashu Hao Qi Zhang +2 位作者 Chao Zhang Kunlei Li Xiaoxue Wang 《Journal of Bionic Engineering》 SCIE EI CSCD 2025年第6期3076-3085,共10页
Inspired by the aquatic-adapted pit structures of the Cybister beetles that enable high-speed swimming,this study employs warp-knitted technology to fabricate drag-reduction swimwear textiles.Eight distinct fabric mor... Inspired by the aquatic-adapted pit structures of the Cybister beetles that enable high-speed swimming,this study employs warp-knitted technology to fabricate drag-reduction swimwear textiles.Eight distinct fabric morphologies were produced,and a self-developed high-precision dynamic drag measurement device was used to systematically analyze the mechanisms underlying the drag-reduction performance of these biomimetic pit structures.The device incorporates a servomotor,ball screw linkage,and high-precision tension sensor,enabling real-time and accurate detection of fluid drag forces.It effectively overcomes the limitations of traditional indirect measurement methods,including dynamic response lag and insufficient accuracy.Experimental results demonstrate that the hydrophobic small-pit fabric(4#)achieves an 84% drag reduction at 400 mm/s,outperforming the control sample(warp-knitted fabric 7#).This significant reduction is attributed to the Cassie state established on the hydrophobic surface,which substantially decreases viscous drag and the microvortices generated by the pit structures,which delay flow separation and effectively minimize pressure drag.Furthermore,small-pit fabrics demonstrate a drag reduction rate 26% to 50% higher than that of large-pit structures,highlighting the critical importance of matching the pit scale to the thickness of the near-wall viscous sublayer for optimal drag reduction.This study establishes a theoretical foundation for the biomimetic design of high-performance drag-reduction swimsuits.The developed drag-measuring device also provides a standardized experimental platform for hydrodynamic studies of flexible materials,supporting a shift from empirical design methodologies to theory-driven approaches in drag-reduction technology and exhibiting significant potential for future advancements. 展开更多
关键词 Drag reduction Warp-knitted swimwear fabrics Dynamic drag measurement Pit-structured fabric Flow separation control
Dolphin-Inspired Skin Microvibrations Offer a Novel Pressure-Dominated Drag Reduction Mechanism 认领 引用 被引量：2
15
作者 Dongyue Wang Hao Liu 《Journal of Bionic Engineering》 SCIE EI CSCD 2025年第2期793-804,共12页
The cutaneous ridges on dolphin skin have long been believed to effectively reduce friction drag, thereby contributing to overall drag reduction. However, since these skin ridges are oriented perpendicular to the swim... The cutaneous ridges on dolphin skin have long been believed to effectively reduce friction drag, thereby contributing to overall drag reduction. However, since these skin ridges are oriented perpendicular to the swimming direction, they also generate additional pressure drag, raising questions about the impact of the shape-induced pressure forces on swimming. Inspired by the microvibrations observed on dolphin skin, we hypothesize that the microstructure on dolphin skin is not static but dynamically oscillates in the form of Longitudinal Micro-Ultrasonic Waves (LMUWs). To explore this, we carried out a series of Computational Fluid Dynamics (CFD) simulations based on Large Eddy Simulation (LES) model to investigate the impact of pressure drag on the total drag acting on an oscillating skin surface under realistic turbulent flow conditions. The results indicate that the dynamic skin oscillations induce a new dynamic Stokes boundary layer, which has the potential to convert pressure drag into a negative force, thereby reducing total drag under the influence of traveling LMUW excitations. Furthermore, a relative velocity ξ, defined as the difference between the wave speed c and the external flow speed U, is introduced to evaluate the drag-reduction effect dominated by pressure. The findings reveal that pressure drag remains negative when ξ > 0. As ξ increases, the thrust effect induced by negative pressure becomes increasingly significant, ultimately counteracting friction drag and eliminating total drag. This pressure-dominated drag reduction mechanism thus demonstrates a novel strategy for the drag reduction technology and the potential of unveiling the mysteries behind dolphin swimming. 展开更多
关键词 Pressure drag Drag reduction Dynamic skin oscillation Dolphin swimming Large Eddy Simulation(LES)
Additive Manufactured,Bioinspired Stainless Steel Surface for Robust Drag Reduction 认领 引用
16
作者 Zhen Lin Peng Xu +10 位作者 Junfei Huang Jinhong Zhang Xiaolong Zhang Lijun Li Yurong Zhang Ruteng Wang Xinping Long Yifeng Lei Changhui Song Daobing Chen Longjian Xue 《Journal of Bionic Engineering》 SCIE EI CSCD 2025年第5期2539-2549,共11页
Bioinspired superhydrophobic surfaces have been used for drag reduction.However,the secondary structures and the air cushions on these surfaces could be destructed in a flow,losing the effect of drag reduction.Here,a ... Bioinspired superhydrophobic surfaces have been used for drag reduction.However,the secondary structures and the air cushions on these surfaces could be destructed in a flow,losing the effect of drag reduction.Here,a stainless-steel surface with mushroom-like cross-section(SMC)and diamond cavities(SMCD)having a drag reduction rate up to 19.37%is developed by 3D printing.The concealed re-entrant structures in SMCD prevent the infiltration of water into the chamber and form gas cushions,which converts the sliding friction at liquid-solid interface into rolling friction at liquid-gas interface,realizing the drag reduction.Meanwhile,98.3%of air can be maintained in the chamber in a flow with Reynolds number(Re)of 9×105,ensuring the drag reduction in a high-velocity flow.Moreover,the continuous top stainless-steel surface and the supporting mesh network protect the critical re-entrant structures,ensuring the robustness of SMC.With the bioinspired design and one-step additive manufacturing process,SMC holds great potential for large-area production and applications requiring robust drag reduction. 展开更多
关键词 Additive manufacturing Bioinspired Re-entrant structure Hydrophobicity Drag reduction
Research Progress on Biomimetic Drag Reduction Materials Inspired by Diverse Organisms:from Principle to Application 认领 引用
17
作者 Lei Tang Hongyi Hu +1 位作者 Zhixiang Zeng Qunji Xue 《Journal of Bionic Engineering》 SCIE EI CSCD 2025年第5期2151-2193,共43页
Reducing the resistance of vehicles,ships,aircraft and other means of transport during movement can significantly improve the speed,save energy and reduce emissions.After billions of years of continuous evolution,orga... Reducing the resistance of vehicles,ships,aircraft and other means of transport during movement can significantly improve the speed,save energy and reduce emissions.After billions of years of continuous evolution,organisms in nature have gradually developed the ability to move at high speed to achieve better survival.These evolved organisms provide a perfect template for the human development of drag reduction materials.Revealing the unique physiological structural characteristics of organisms and their relationship with resistance during movement can provide a feasible approach tosolving the problem of reducing friction resistance.Whether flying in the sky,running on the ground,swimming in the water,or even living in the soil,many creatures in various environments have the ability to reduce resistance.Driven by these inspirations,researchers have done a lot of work to explore and imitate these biological epidermis structures to achieve drag reduction.In this paper,the biomimetic drag reduction materials is introduced in detail in the order of drag reduction mechanism,structural characteristics of biological epidermis(including marine animals,flying animals,soil animals and plants),biomimetic preparation methods,performance testing methods and application fields.Finally,the potential of various biomimetic drag reduction materials in engineering application and the problems to be overcome are summarized and prospected.This paper can help readers comprehensively understand the research progress of biomimetic drag reduction materials,and provide reference for further designing the next generation of drag reduction materials. 展开更多
关键词 Biomimetic drag reduction material Principle Inspiration Fabrication Examination Application
Effect of dynamic flexible biomimetic fishtail on the wake characteristics and aerodynamic drag of high-speed trains 认领 引用
18
作者 LI Zhi-wei ZHAO Yan-jia +3 位作者 ZENG Guang-zhi ZHU Hai-bin LIU Ying HUANG Sha 《Journal of Central South University》 SCIE EI CAS CSCD 2025年第12期4720-4735,共16页
The increase in aerodynamic drag brings high energy consumption,which is a critical issue in the development of high-speed trains.Inspired by the excellent hydrodynamic characteristics of fish movement in nature,a two... The increase in aerodynamic drag brings high energy consumption,which is a critical issue in the development of high-speed trains.Inspired by the excellent hydrodynamic characteristics of fish movement in nature,a two-dimensional numerical simulation method based on spring-smoothing model and adaptive mesh technology was utilized to explore the effects of different fishtail structures and two flexible motion modes(Eel mode and Lunate-tail mode)on the wake of high-speed trains,and to assess their potential for aerodynamic drag reduction.Results indicate that the biomimetic fishtail successfully suppresses the alternating shedding of vortices in the wake,and induces the aerodynamic drag fluctuation period to align with the fishtail oscillation period.The fishtail length,oscillation mode,and frequency have a significant impact on the wake flow and aerodynamic drag of the train.Among these,a 1850 mm Eel fishtail with parameters ofλ=1 and T=8 s achieves the optimal drag reduction effect,with drag reduction rates of 39.12%and 26.00%for the tail car and the entire train,respectively.These findings provide a theoretical basis for the design of new low-resistance railway trains,promoting the sustainable development of rail transit towards goals of high-speed and energy-efficient. 展开更多
关键词 high-speed train aerodynamic drag reduction wake characteristics bionics flexible fishtail
暂未订购 下载PDF
Turbulent drag reduction by sector-shaped counter-flow dielectric barrier discharge plasma actuator 认领 引用
19
作者 Borui Zheng Shaojie Qi +3 位作者 Minghao Yu Jianbo Zhang Linwu Wang Dongliang Bian 《Chinese Physics B》 SCIE EI CAS CSCD 2025年第2期362-370,共9页
The primary objective in aircraft transportation is to minimize turbulent drag, thereby conserving energy and reducing emissions. We propose a sector-shaped counter-flow dielectric barrier discharge plasma actuator, w... The primary objective in aircraft transportation is to minimize turbulent drag, thereby conserving energy and reducing emissions. We propose a sector-shaped counter-flow dielectric barrier discharge plasma actuator, which leverages jet synthesis for drag reduction. A drag control experiment was conducted in a low-speed wind tunnel with a controlled flow velocity of 9.6 m/s(Re = 1.445 × 104). This study investigated the effects of varying pulse frequencies and actuation voltages on the turbulent boundary layer. Using a hot-wire measurement system, we analyzed the pulsating and time-averaged velocity distributions within the boundary layer to evaluate the streamwise turbulent drag reduction. The results show that the local TDR decreases as the pulse frequency increases, reaching a maximum reduction of approximately 20.97% at a pulse frequency of 50 Hz. In addition, as the actuation voltage increases, the friction coefficient decreases, increasing the drag reduction rate. The maximum drag reduction of approximately 33.34% is achieved at an actuation voltage of 10 kV. 展开更多
关键词 plasma flow control turbulent boundary layer turbulent drag reduction
暂未订购 下载PDF
Parameterizing the Sea Surface Drag Coefficient over Aiyetoro in Ilaje Local Government Area,Ondo State,Southwestern Nigeria 认领 引用
20
作者 Adekunle Ayodotun Osinowo Lateef Adesola Afolabi +2 位作者 Pasquale Contestabile Segun Ohunayo Ekudehinwa Gideon Efeoghene Ovwuwonye 《Sustainable Marine Structures》 2025年第3期43-62,共20页
Ocean surface waves and upper sea circulation are primarily propelled by wind force and are usually expressed in terms of sea surface drag coefficient(cd)that increases with sea surface roughness and wind speed.Thi... Ocean surface waves and upper sea circulation are primarily propelled by wind force and are usually expressed in terms of sea surface drag coefficient(cd)that increases with sea surface roughness and wind speed.This work discussed the cdparameterization at Aiyetoro,Ilaje Local Government Area,Ondo State,Southwestern Nigeria,to quantify the exchange of momentum in this region,The dependence of cd on some one hourly averaged variables sourced from ERA5 Reanalysis over a 71 year period(1950-2020)was clearly analysed.Results of the monthly mean and variability of cd and u10 over the study area showed that November had the lowest monthly mean cd and u10,with values of 0.000825 and 3.38 m/s,respectively,and August had the highest values of 0.001031 and 5.66 m/s,respectively.Furthermore,the cd variability is lowest(63.24%)in November and highest(106.35%)in August.The variability for u10 is lowest in March(198.18%)and greatest in October(304.37%).For the study location,five parameterizations,were statistically evaluated for the predictive power of cd on an annual,seasonal and monthly basis.Furthermore,the cd showed improved performance when using monthly values than when using annual and seasonal values.The equations yielded better performance in the wet season than in the dry season. 展开更多
关键词 Era5 Reanalysis Data Sea Surface Drag Parameterization Wind-Sea Interaction Wave Dynamics Momentum
暂未订购 下载PDF
已选0条
引用分析
参考文献
引证文献
 统计分析
检索结果
已选文献
上一页 1 2 … 250 下一页 到第 页
在线咨询 使用帮助 返回顶部 意见反馈