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Inherent mechanism of breakdown in laminar-turbulent transition of plane channel flows 被引量:14
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作者 LUO Jisheng, WANG Xinjun & ZHOU Heng Department of Mechanics, Tianjin University Liu-Hui Center of Mathematics, Nankai and Tianjin University, Tianjin 300071, China 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2005年第2期228-236,共9页
Laminar-turbulent transition is an old yet unsolved problem. Notwithstanding the great effort made, there is an important question that seems not to have been addressed yet, that is, what is the inherent mechanism of ... Laminar-turbulent transition is an old yet unsolved problem. Notwithstanding the great effort made, there is an important question that seems not to have been addressed yet, that is, what is the inherent mechanism of breakdown that eventually leads to transition? The conventional idea is that the transition starts from the amplification of disturbances, and when the disturbances become larger, higher harmonics will be generated due to nonlinear effect, making the flow more and more complicated, and finally turbulent. Though the scenario seems clear, yet there is a missing link, that is, what happens in the breakdown process. Here we show by analyzing the results from direct numerical simulations that the change of stability characteristics of the mean flow profile plays a key role in the breakdown process. 展开更多
关键词 laminar-turbulent transition breakdown PLANE channel flow.
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矩形明渠三维紊流的数值模拟 被引量:3
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作者 林斌良 Shion.,K 《水利学报》 EI CSCD 北大核心 1994年第3期47-56,共10页
在明渠三维流动中,紊流产生的二次流起关键作用.它对主流流场分布、壁面应力及污染物的扩散有很大影响,有时还影响床面的稳定.K-ε紊流模型及类似的双方程模型不能计算这种二次流动.本文将非线性K-ε紊流模型用于明渠三维紊流... 在明渠三维流动中,紊流产生的二次流起关键作用.它对主流流场分布、壁面应力及污染物的扩散有很大影响,有时还影响床面的稳定.K-ε紊流模型及类似的双方程模型不能计算这种二次流动.本文将非线性K-ε紊流模型用于明渠三维紊流的计算,模型用张量形式推出,比代数应力模型更易推厂到复杂边界流动.应用这一模型及另两种代数应力模型对矩形明渠流动进行计算.所得结果,尤其是表述紊流特征的量,与实测资料进行了详细比较.并对各种紊流模型及边界条件处理方法做了评估. 展开更多
关键词 三维紊流 矩形明渠 数值模拟
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基于Navier-Stokes方程残差的隐式大涡模拟有限元模型 被引量:14
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作者 陈林烽 《力学学报》 EI CSCD 北大核心 2020年第5期1314-1322,I0003,共10页
对应于湍流的大尺度与小尺度流场信息,本文在有限元的框架下,假设Navier-Stokes方程的解的形函数由大尺度和不可解尺度形函数叠加组成,引入对应的权函数,将Navier-Stokes方程的有限元变分形式分解为大尺度和不可解尺度系统.根据不可解... 对应于湍流的大尺度与小尺度流场信息,本文在有限元的框架下,假设Navier-Stokes方程的解的形函数由大尺度和不可解尺度形函数叠加组成,引入对应的权函数,将Navier-Stokes方程的有限元变分形式分解为大尺度和不可解尺度系统.根据不可解尺度系统,构建基于Navier-Stokes大尺度方程残差的不可解尺度模型,将其代入Navier-Stokes方程的大尺度系统,进而数值求解大尺度系统得到Navier-Stokes方程的大尺度解.该方法无需像传统的大涡模拟方法那样对方程的解进行过滤,通过对形函数进行尺度分解实现解的尺度分解.本文使用该方法的自编程序代码开展了槽道湍流的数值模拟.通过与有限差分大涡模拟、DNS计算结果的比较,发现在使用较少网格情况下该方法预测的平均流向速度在近壁区与DNS数据吻合,在黏性外层略偏高;该方法对雷诺应力预测偏低导致从流向向垂向方向上湍动能输运略偏低.流向速度等值面图显示该方法有效捕捉到了大尺度旋涡结构;同时在近壁区可以观察到明显的低速条带结构. 展开更多
关键词 大涡数值模拟 有限元方法 多尺度方法 不可解尺度模型 槽道湍流
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大涡模拟中亚格子模型的改进及其在槽道湍流中的应用 被引量:9
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作者 肖红林 罗纪生 《航空动力学报》 EI CAS CSCD 北大核心 2007年第4期583-587,共5页
在用大涡模拟的方法计算具有强剪切的槽道湍流时,常用的亚格子应力模型,包括考虑壁面修正的模型,都会出现平均流剖面偏高的现象.这表明在壁面附近亚格子应力模型还不能描述实际情况.针对这一问题,修正了亚格子雷诺应力模型的壁面函数,... 在用大涡模拟的方法计算具有强剪切的槽道湍流时,常用的亚格子应力模型,包括考虑壁面修正的模型,都会出现平均流剖面偏高的现象.这表明在壁面附近亚格子应力模型还不能描述实际情况.针对这一问题,修正了亚格子雷诺应力模型的壁面函数,得到了较好的计算结果.用修正后的模型计算出的平均速度分布、均方根速度的分布以及雷诺应力的分布,均与直接数值模拟(DNS)的结果吻合较好. 展开更多
关键词 航空 航天推进系统 槽道湍流 大涡模拟 亚格子雷诺应力 涡粘系数 壁面函数
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LARGE EDDY SIMULATION OF THERMALLY-STRATIFIED TURBULENT CHANNEL FLOW WITH TEMPERATURE OSCILLATION ON THE BOTTOM WALL 被引量:9
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作者 DONGYu-hong LUXi-yun ZHUANGLi-xian 《Journal of Hydrodynamics》 SCIE EI CSCD 2004年第1期34-38,共5页
Thermally-stratified shear turbulent channel flow with temperatureoscillation on the bottom wall of the channel was investigated with the Large Eddy Simulation (LES)approach coupled with dynamic Sub-Grid-Scale (SGS) m... Thermally-stratified shear turbulent channel flow with temperatureoscillation on the bottom wall of the channel was investigated with the Large Eddy Simulation (LES)approach coupled with dynamic Sub-Grid-Scale (SGS) models. The effect of temperature oscillation onthe turbulent channel flow behavior was examined. The phase-averaged velocities and temperature, andflow structures at different Richardson numbers and periods of the oscillation was analyzed. 展开更多
关键词 large eddy simulation (LES) turbulent channel flow thermally-stratifiedturbulence sub-grid scale (SGS) model oscillatory heat transfer temperature oscillation
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Numerical investigation of particle saltation in the bed-load regime 被引量:10
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作者 JI ChunNing ANTE Munjiza +2 位作者 ELDAD Avital XU Dong JOHN Williams 《Science China(Technological Sciences)》 SCIE EI CAS 2014年第8期1500-1511,共12页
This paper numerically investigates particle saltation in a turbulent channel flow having a rough bed consisting of 2–3 layers of densely packed spheres.In this study,we combined three the state-of-the-art technologi... This paper numerically investigates particle saltation in a turbulent channel flow having a rough bed consisting of 2–3 layers of densely packed spheres.In this study,we combined three the state-of-the-art technologies,i.e.,the direct numerical simulation of turbulent flow,the combined finite-discrete element modelling of the deformation,movement and collision of the particles,and the immersed boundary method for the fluid-solid interaction.Here we verify our code by comparing the flow and particle statistical features with the published data and then present the hydrodynamic forces acting on a particle together with the particle coordinates and velocities,during a typical saltation.We found strong correlation between the abruptly decreasing particle stream-wise velocity and the increasing vertical velocity at collision,which indicates that the continuous saltation of large grain-size particles is controlled by collision parameters such as particle incident angle,local rough bed packing arrangement,and particle density,etc.This physical process is different from that of particle entrainment in which turbulence coherence structures play an important role.Probability distribution functions of several important saltation parameters and the relationships between them are presented.The results show that the saltating particles hitting the windward side of the bed particles are more likely to bounce off the rough bed than those hitting the leeside.Based on the above findings,saltation mechanisms of large grain-size particles in turbulent channel flow are presented. 展开更多
关键词 particle saltation bed-load regime hydrodynamic forces turbulent channel flow
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THREE-DIMENSIONAL LARGE EDDY SIMULATION OF FREE SURFACE TURBULENT FLOW IN OPEN CHANNEL WITHIN SUBMERGED VEGETATION DOMAIN 被引量:8
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作者 SuXiao-hui LiC.W ChenBi-hong 《Journal of Hydrodynamics》 SCIE EI CSCD 2003年第3期35-43,共9页
A three-dimensional Large Eddy Simulation (LES) has been performed ofhydrodynamic behavior of turbulent flow in open channel that the lower part of the domain isoccupied by a drag force layer to represent vegetation. ... A three-dimensional Large Eddy Simulation (LES) has been performed ofhydrodynamic behavior of turbulent flow in open channel that the lower part of the domain isoccupied by a drag force layer to represent vegetation. One equation model is used to closing theresolvable scale equations. The turbulent characteristic length is parameterized by a k-l model. Aphenomenal model is employed to express the performance of vegetation in the open channel. Theresult reveals that the present model has the capacity of describing three-dimensional structure oflarge eddy appearing in turbulent flow in open channel with vegetation region and has the capacityof tracing the development of large eddies. 展开更多
关键词 LES turbulent flow open channel VEGETATION
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NUMERICAL SIMULATIONS OF TURBULENT FLOWS PASSED THROUGH AN ORIFICE ENERGY DISSIPATOR WITHIN A FLOOD DISCHARGE TUNNEL 被引量:6
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作者 Yang, Yongquan Zhao, haiheng 《Journal of Hydrodynamics》 SCIE EI CSCD 1992年第3期27-33,共7页
When water flows through a multiple-orifice energy disspator, flow vibration and cavitation may become very important problems. A new kind of the energy dissipator has recieved much attention because of its effectiven... When water flows through a multiple-orifice energy disspator, flow vibration and cavitation may become very important problems. A new kind of the energy dissipator has recieved much attention because of its effectiveness in energy dissipation. In this paper numerical simulations of turbulent flows in a dissipator were presented. The flow was considered to be an asymmetric two-dimensional steady flow. K-Ε turbulent model was used and solution procedure was described. The calculation was performed with different flow conditions. Calculated results of the flow field are compared with experiments. The results demonstrate that turbulent flow through dissipator can be predicted. 展开更多
关键词 CAVITATION channel flow Energy dissipators Numerical methods turbulent flow
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QUADRANT ANALYSIS OF BUBBLE INDUCED VELOCITY FLUCTUATIONS IN A TRANSITIONAL BOUNDARY LAYER 被引量:6
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作者 HUANG Jian MURAI Yuichi YAMAMOTO Fujio 《Journal of Hydrodynamics》 SCIE EI CSCD 2009年第1期93-99,共7页
Our previous study showed that the frictional drag decreases with increasing void fraction at Re〉1300, while it increases at Re 〈 1000. Decomposition of the Reynolds shear stress also implied that bubbles induce iso... Our previous study showed that the frictional drag decreases with increasing void fraction at Re〉1300, while it increases at Re 〈 1000. Decomposition of the Reynolds shear stress also implied that bubbles induce isotropy of turbulence. In order to confirm our previous analysis and to further investigate flow fields in the vicinity of bubbles, we analyze velocity fluctuations on the quadrant space in the streamwise and transverse directions (u′-v′ plane). Here, we focus on two specific Reynolds numbers (at Re≈900 and ≈1410, which are close to the laminar-to-turbulent transition regime) and discuss bubble effects on sweep (u′〉 0, v′〈 0 ) and ejection (u′〈 0, v′〉 0) events as a function of the Reynolds number. We also illustrate velocity fluctuations in the vicinity of an individual bubble and a swarm of bubbles on the u′- v′ coordinates. The results show that a bubble swarm suppresses the velocity fluctuations at Re≈1410. 展开更多
关键词 bubbly channel flow Particle Tracking Velocimetry (PTV) quadrant analysis velocity fluctuation boundary layer laminar-to-turbulent transition
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平底光面明渠中紊流猝发的特性研究 被引量:4
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作者 毛野 杨华 +1 位作者 袁新明 吉庆丰 《水动力学研究与进展(A辑)》 CSCD 北大核心 2002年第4期413-421,共9页
在保持循环水槽底部平整和表面光滑仅改变流速的条件下进行了系统的实验研究 ,重点研究了雷诺数ReR 对紊流猝发的形态和特性的影响。采用流场综合分析法将流动显示与计算机图像处理相结合 ,与常用的点流速条件检测猝发现象相比有了明显... 在保持循环水槽底部平整和表面光滑仅改变流速的条件下进行了系统的实验研究 ,重点研究了雷诺数ReR 对紊流猝发的形态和特性的影响。采用流场综合分析法将流动显示与计算机图像处理相结合 ,与常用的点流速条件检测猝发现象相比有了明显改进 ,有利于加深对明渠紊流猝发的认识。PIV激光片光源频闪技术拍摄的猝发系列照片生动展示了明渠紊流流场的猝发特性 ,可用于直接分析 ;再经过计算机图像处理后可绘制流速矢量场图并进行相关计算分析。试验表明猝发喷射角约为 4 0°~ 6 0°,雷诺数ReR 增大会使喷射角略有增加 ;猝发喷射高度约可达到边界层名义厚度的 1/4~ 1/3高度。雷诺数ReR 增大明显增加了多头群体喷射现象 ,无量纲猝发周期加大 ,喷射尺度和清扫尺度也有增大趋势。对试验的分析表明雷诺数ReR 对明渠中紊流猝发的特性有重要影响 ,增大ReR 展开更多
关键词 紊流 拟序结构 猝发现象 明渠水流 PIV
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LARGE EDDY SIMULATION OF PARTICLE TRANSPORT IN FULLY DEVELOPED VERTICAL TURBULENT CHANNEL FLOW 被引量:4
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作者 WANGAn LIUNan-sheng LUXi-yun 《Journal of Hydrodynamics》 SCIE EI CSCD 2004年第4期386-392,共7页
Fully developed vertical turbulent channel flow with particle transport wasinvestigated by use of Large Eddy Simulation (LES) approach coupled with dynamic the Sub-Grid Scale(SGS) model. It was assumed that the motion... Fully developed vertical turbulent channel flow with particle transport wasinvestigated by use of Large Eddy Simulation (LES) approach coupled with dynamic the Sub-Grid Scale(SGS) model. It was assumed that the motion of each particle is followed in a Lagrangian frame ofreference driven by the forces exerted by fluid motion and gravity under the condition of one-waycoupling. The goal of this study is to investigate the effectiveness of the LES technique forpredicting particle transport in turbulent flow and the behavior of particle-laden turbulent channelflow for three kinds of particles at different Stokes numbers. To depict the behavior ofparticle-laden turbulent channel flow, statistical quantities including particle fluctuation andfluid-particle velocity correlation, and visualization of the particle number density field wereanalyzed. 展开更多
关键词 large eddy simulation (LES) turbulent channel flow particle transport particle-laden turbulent flow sub-grid scale (SGS) model
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AN INVESTIGATION OF TURBULENT HEAT TRANSFER IN CHANNEL FLOWS BY LARGE EDDY SIMULATION 被引量:4
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作者 Dong Yu-hong, Zhong Feng-quan, Lu Xi-yun, Zhuang Li-xian Department of Mechanics and Mechanical Engineering, University of Science and Technology of China, Hefei 230026, China 《Journal of Hydrodynamics》 SCIE EI CSCD 2002年第2期29-35,共7页
Large Eddy Simulation (LES) of fully developed turbulent channel flow with heat transfer was performed to investigate the effects of the Reynolds number on the turbulence behavior. In the present study, the bottom wal... Large Eddy Simulation (LES) of fully developed turbulent channel flow with heat transfer was performed to investigate the effects of the Reynolds number on the turbulence behavior. In the present study, the bottom wall of the channel was cooled and the top wall was heated. The Reynolds numbers, based on the central mean-velocity and the half-width of the channel, were chosen as 4000, 6000, 10 4 and 2×10 4, and the Prandtl number as 1.0. To validate our calculations, the present results were compared with available data obtained by Direct Numerical Simulation (DNS), which proves to be in good agreement with each other. To reveal the effects of the Reynolds number, some typical quantities, including the velocity fluctuations, temperature fluctuation, heat fluxes and turbulent Prandtl number, were studied. 展开更多
关键词 Large Eddy Simulation (LES) turbulent channel flow Subgrid Scale (SGS) model heat transfer stratified turbulence
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Numerical study of the near-wall vortical structures in particle-laden turbulent flow by a new vortex identification method-Liutex
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作者 Farid Rousta Goodarz Ahmadi +1 位作者 Bamdad Lessani Chaoqun Liu 《Journal of Hydrodynamics》 SCIE EI CSCD 2024年第1期53-60,共8页
This study investigates turbulent particle-laden channel flows using direct numerical simulations employing the Eulerian-Lagrangian method.A two-way coupling approach is adopted to explore the mutual interaction betwe... This study investigates turbulent particle-laden channel flows using direct numerical simulations employing the Eulerian-Lagrangian method.A two-way coupling approach is adopted to explore the mutual interaction between particles and fluid flow.The considered cases include flow with particle Stokes number varying from St=2 up to St=100 while maintaining a constant Reynolds number of Reτ=180 across all cases.A novel vortex identification method,Liutex(Rortex),is employed to assess its efficacy in capturing near-wall turbulent coherent structures and their interactions with particles.The Liutex method provides valuable information on vortex strength and vectors at each location,enabling a detailed examination of the complex interaction between fluid and particulate phases.As widely acknowledged,the interplay between clockwise and counterclockwise vortices in the near-wall region gives rise to low-speed streaks along the wall.These low-speed streaks serve as preferential zones for particle concentration,depending upon the particle Stokes number.It is shown that the Liutex method can capture these vortices and identify the location of low-speed streaks.Additionally,it is observed that the particle Stokes number(size)significantly affects both the strength of these vortices and the streaky structure exhibited by particles.Furthermore,a quantitative analysis of particle behavior in the near-wall region and the formation of elongated particle lines was carried out.This involved examining the average fluid streamwise velocity fluctuations at particle locations,average particle concentration,and the normal velocity of particles for each set of particle Stokes numbers.The investigation reveals the intricate interplay between particles and near-wall structures and the significant influence of particles Stokes number.This study contributes to a deeper understanding of turbulent particle-laden channel flow dynamics. 展开更多
关键词 turbulent channel flow particle-laden flow direct numerical simulation(DNS) Eulerian-Lagrangian vortex identification turbulence coherent structures Liutex
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The mechanical energy equation for total flow in open channels 被引量:4
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作者 刘士和 范敏 薛娇 《Journal of Hydrodynamics》 SCIE EI CSCD 2014年第3期416-423,共8页
The mechanical energy equation is a fundamental equation of a 1-D mathematical model in Hydraulics and Engineering Fluid Mechanics. This equation for the total flow used to be deduced by extending the Bernoulli's equ... The mechanical energy equation is a fundamental equation of a 1-D mathematical model in Hydraulics and Engineering Fluid Mechanics. This equation for the total flow used to be deduced by extending the Bernoulli's equation for the ideal fluid in the streamline to a stream tube, and then revised by considering the viscous effect and integrated on the cross section. This derivation is not rigorous and the effect of turbulence is not considered. In this paper, the energy equation for the total flow is derived by using the Navier-Stokes equations in Fluid Mechanics, the results are as follows:(1) A new energy equation for steady channel flows of incompressible homogeneous liquid is obtained, which includes the variation of the turbulent kinetic energy along the channel, the formula for the mechanical energy loss of the total flow can be determined directly in the deduction process.(2) The theoretical solution of the velocity field for laminar flows in a rectangular open channel is obtained and the mechanical energy loss in the energy equation is calculated. The variations of the coefficient of the mechanical energy loss against the Reynolds number and the width-depth ratio are obtained.(3) The turbulent flow in a rectangular open channel is simulated using 3-D Reynolds averaged equations closed by the Reynolds stress model(RSM), and the variations of the coefficient of the mechanical energy loss against the Reynolds number and the width-depth ratio are discussed. 展开更多
关键词 open channel mechanical energy equation steady flow turbulent flow
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Assessment of subgrid-scale models in wall-modeled large-eddy simulations of turbulent channel flows 被引量:2
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作者 Wei-wen Zhao Fu-chang Zhou +1 位作者 Guo-qing Fan De-cheng Wan 《Journal of Hydrodynamics》 SCIE EI CSCD 2023年第3期407-416,共10页
Considering the demanding of grid requirements for high-Reynolds-number wall-bounded flow,the wall-modeled large-eddy simulation(WMLES)is an attractive method to deal with near wall turbulence.However,the effect of su... Considering the demanding of grid requirements for high-Reynolds-number wall-bounded flow,the wall-modeled large-eddy simulation(WMLES)is an attractive method to deal with near wall turbulence.However,the effect of subgrid-scale(SGS)models for wall-bounded turbulent flow in combination with wall stress models is still unclear.In this paper,turbulent channel flow at Reτ=1000 are numerically simulated by WMLES in conjunction with four different SGS models,i.e.,the wall-adapting local eddy-viscosity model,the dynamic Smagorinsky model,the dynamic SGS kinetic energy model and the dynamic Lagrangian model.The mean velocity profiles are compared with the law of the wall,and the velocity fluctuations are compared with direct numerical simulation data.The energy spectrum of velocity and wall pressure fluctuations are presented and the role of SGS models on predicting turbulent channel flow with WMLES is discussed. 展开更多
关键词 Wall-modeled large-eddy simulation(WMLES) subgrid-scale(SGS)model turbulent channel flow energy spectra
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Numerical Research on the Fiber Suspensions in a Turbulent T-shaped Branching Channel Flow 被引量:4
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作者 张善亮 林建忠 张卫峰 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2007年第1期30-38,共9页
The concentration and orientation of fiber in a turbulent T-shaped branching channel flow are investi-gated numerically. The Reynolds averaged Navier-Stokes equations together with the Reynolds stress turbulent model ... The concentration and orientation of fiber in a turbulent T-shaped branching channel flow are investi-gated numerically. The Reynolds averaged Navier-Stokes equations together with the Reynolds stress turbulent model are solved for the mean flow field and the turbulent kinetic energy. The fluctuating velocities of the fluid are assumed as a random variable with Gaussian distribution whose variance is related to the turbulent kinetic energy. The slender-body theory is used to simulate the fiber motion based on the known mean and fluctuating velocities of the fluid. The results show that at low Reynolds number, fiber concentration is high in the flow separation regions, and fiber orientation throughout the channel is widely distributed with a slight preference of aligning along the horizontal axis. With increasing of Re, the high concentration region disappears, and fiber orientation becomes ho-mogeneous without any preferred direction. At high Reynolds number, fiber concentration increases gradually along the flow direction. The differences in the distribution of concentration and orientation between different fiber aspect ratio are evident only at low Re. Both Re and fiber aspect ratio have small effect on the variance of orientation angle. 展开更多
关键词 fiber suspension DISTRIBUTION ORIENTATION turbulent branching channel flow numerical simulation
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基于壁面主动变形的湍流减阻控制研究 被引量:6
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作者 葛铭纬 许春晓 +1 位作者 黄伟希 崔桂香 《力学学报》 EI CSCD 北大核心 2012年第4期653-663,共11页
采用谱方法,对反向控制下壁面主动变形的槽道湍流进行了直接数值模拟研究.结果表明,在壁面最大变形量小于5倍黏性尺度条件下,压差阻力可略,摩擦阻力降低7.6%.施加控制后,湍流强度和雷诺应力受到明显抑制,平均速度剖面对数区上移.受壁面... 采用谱方法,对反向控制下壁面主动变形的槽道湍流进行了直接数值模拟研究.结果表明,在壁面最大变形量小于5倍黏性尺度条件下,压差阻力可略,摩擦阻力降低7.6%.施加控制后,湍流强度和雷诺应力受到明显抑制,平均速度剖面对数区上移.受壁面法向运动的影响,条带结构强度减弱、尺度变大;流向涡外移且强度减弱,其倾斜和抬起的角度均有不同程度的减小.壁面变形呈现流向拉长的凹槽结构,其平均间距为90倍黏性尺度. 展开更多
关键词 槽道湍流 直接数值模拟 反向控制 壁面变形 湍流减阻
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辐射加热颗粒槽道湍流两相流的相间传热特性
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作者 唐晓峰 潘明 +1 位作者 杨文武 董宇红 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2024年第2期54-64,共11页
本文采用直接数值模拟方法结合拉格朗日点-粒模型研究了携带辐射热惯性颗粒的竖直槽道湍流两相流相间传热特性.研究中采用双向耦合模型描述分散相颗粒与流体之间的动量交换和热交换,辐射强度和颗粒Stokes数范围分别为1≤q/q0≤20,0.36&#... 本文采用直接数值模拟方法结合拉格朗日点-粒模型研究了携带辐射热惯性颗粒的竖直槽道湍流两相流相间传热特性.研究中采用双向耦合模型描述分散相颗粒与流体之间的动量交换和热交换,辐射强度和颗粒Stokes数范围分别为1≤q/q0≤20,0.36×10^(−1)≤Stf≤2.16×10^(−1).研究发现辐射加热颗粒对流体的动力学调制加速了流体运动,使湍流强度增大.高辐射下的小Stokes数颗粒能显著加热流体.我们从流场时均温度方程出发,导出了两相流系统中相间传热Nusselt数的理论表达式,理论分析表明相间传热引起冷板和热板Nusselt数的差异,并进一步得到了相间传热效率与颗粒Stokes数及颗粒所受辐射强度的标度关系. 展开更多
关键词 加热流体 Stokes数 传热效率 辐射加热 辐射强度 直接数值模拟 拉格朗日点 理论表达式
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槽道湍流展向振荡电磁力减阻的机理研究 被引量:6
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作者 梅栋杰 范宝春 +1 位作者 陈耀慧 叶经方 《力学学报》 EI CSCD 北大核心 2011年第4期653-659,共7页
对槽道湍流的展向振荡电磁力控制进行了实验和数值研究.实验通过PIV系统和浮动床阻力测试系统记录近壁区的条带变化和壁面阻力变化.计算时,利用谱方法直接模拟电磁力控制下的近壁流场.实验和计算结果定性一致,皆表明展向振荡电磁力可以... 对槽道湍流的展向振荡电磁力控制进行了实验和数值研究.实验通过PIV系统和浮动床阻力测试系统记录近壁区的条带变化和壁面阻力变化.计算时,利用谱方法直接模拟电磁力控制下的近壁流场.实验和计算结果定性一致,皆表明展向振荡电磁力可以减少壁面阻力,并使条带倾斜.计算结果还进一步揭示了电磁力减阻的机理.电磁力诱导产生的流向涡与壁湍流的相互作用,在近壁处形成负的脉动展向涡,该涡将导致流向涡的倾斜和振荡,从而抑制湍流,减少壁面阻力. 展开更多
关键词 展向振荡电磁力 槽道湍流 减阻机理 数值模拟
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Artificial neural network-based subgrid-scale models for LES of compressible turbulent channel flow 被引量:1
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作者 Qingjia Meng Zhou Jiang Jianchun Wang 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2023年第1期58-69,共12页
Fully connected neural networks(FCNNs)have been developed for the closure of subgrid-scale(SGS)stress and SGS heat flux in large-eddy simulations of compressible turbulent channel flow.The FCNNbased SGS model trained ... Fully connected neural networks(FCNNs)have been developed for the closure of subgrid-scale(SGS)stress and SGS heat flux in large-eddy simulations of compressible turbulent channel flow.The FCNNbased SGS model trained using data with Mach number Ma=3.0 and Reynolds number Re=3000 was applied to situations with different Mach numbers and Reynolds numbers.The input variables of the neural network model were the filtered velocity gradients and temperature gradients at a single spatial grid point.The a priori test showed that the FCNN model had a correlation coefficient larger than 0.91 and a relative error smaller than 0.43,with much better reconstructions of SGS unclosed terms than the dynamic Smagorinsky model(DSM).In a posteriori test,the behavior of the FCNN model was marginally better than that of the DSM in predicting the mean velocity profiles,mean temperature profiles,turbulent intensities,total Reynolds stress,total Reynolds heat flux,and mean SGS flux of kinetic energy,and outperformed the Smagorinsky model. 展开更多
关键词 Compressible turbulent channel flow Fully connected neural network model Large eddy simulation
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