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Experimental study on particle dispersion between particle-laden jet and supersonic crossflow in cavity-structured channel 认领 引用
1
作者 Likun MA Pengnian YANG +5 位作者 Zhixun XIA Yifan DUAN Yunchao FENG Libei ZHAO Kangchun ZHAO Luxi XU 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2025年第6期260-271,共12页
Dispersion of Particle-laden Jet in Supersonic Crossflow(PJSC)is an essential process in many applications,experimental study on which,however,has rarely been reported.In order to gain physical insights into PJSC,a sp... Dispersion of Particle-laden Jet in Supersonic Crossflow(PJSC)is an essential process in many applications,experimental study on which,however,has rarely been reported.In order to gain physical insights into PJSC,a specialized experimental setup capable of producing a supersonic crossflow at Mach 2.6 and a particle-laden jet with particle mass loading up to 60%is developed.Visualization of the particles motion is achieved with the help of high-speed planar laser scattering technology.The dispersion characteristics of PJSC within a supersonic channel structured by cavity are systematically analyzed through six experimental cases.The results indicate that the vortices have a significant influence on particle dispersion,leading to preferential concentration of particles.i.e.particle clusters.The particle dispersion is summarized as the"scale dispersion"pattern.The primary pathways for particles entering the cavity are identified as the shear layer above the cavity and collisions at the cavity rear edge.Among the studied factors,the momentum flux ratio exerts the most substantial influence on the dispersion process.Importantly,a reduction in the injection distance is correlated with less particles entering the cavity.The insights gained from this research provide essential references for furthering understanding particle dispersion mechanisms in supersonic flows and developing highly accurate numerical models. 展开更多
关键词 Supersonic crossflow Particle-laden jet Particledispersion Scaledispersion Cavity
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Characteristics of turbulence transport for momentum and heat in particle-laden turbulent vertical channel flows 认领 引用 被引量：4
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作者 Caixi Liu Shuai Tang +1 位作者 Lian Shen Yuhong Dong 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2017年第5期833-845,共13页
The dynamic and thermal performance of particle-laden turbulent flow is investigated via direction numerical simulation combined with the Lagrangian point-particle tracking under the condition of two-way coupling, wit... The dynamic and thermal performance of particle-laden turbulent flow is investigated via direction numerical simulation combined with the Lagrangian point-particle tracking under the condition of two-way coupling, with a focus on the contributions of particle feedback effect to momentum and heat transfer of turbulence. We take into account the effects of particles on flow drag and Nusselt number and explore the possibility of drag reduction in conjunction with heat transfer enhancement in particle-laden turbulent flows. The effects of particles on momentum and heat transfer are analyzed, and the possibility of drag reduction in conjunction with heat transfer enhancement for the prototypical case of particle-laden turbulent channel flows is addressed. We present results of turbulence modification and heat transfer in turbulent particle-laden channel flow, which shows the heat transfer reduction when large inertial particles with low specific heat capacity are added to the flow. However, we also found an enhancement of the heat transfer and a small reduction of the flow drag when particles with high specific heat capacity are involved. The present results show that particles, which are active agents, interact not only with the velocity field, but also the temperature field and can cause a dissimilarity in momentum and heat transport. This demonstrates that the possibility to increase heat transfer and suppress friction drag can be achieved with addition of particles with different thermal properties. 展开更多
关键词 Direction numerical simulation (DNS) Lagrangian tracking approach Flow drag Heat transfer Particle-laden flow
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Large-eddy Simulation of Near-field Dynamics in a Particle-laden Round Turbulent Jet 认领 引用 被引量：4
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作者 王兵 张会强 王希麟 《Chinese Journal of Aeronautics》 SCIE EI CAS 2010年第2期162-169,共8页
This article investigates the near-field dynamics in a particle-laden round turbulent jet in a large-eddy simulation （LES）. A point-force two-way coupling model is adopted in the simulation to reveal the particle mo... This article investigates the near-field dynamics in a particle-laden round turbulent jet in a large-eddy simulation （LES）. A point-force two-way coupling model is adopted in the simulation to reveal the particle modulation of turbulence. The particles mainly excite the initial instability of the jet and bring about the earlier breakup of vortex rings in the near-field. The flow fluc- tuating intensity either in the axial or in the radial directions is hence increased by particles. The article also describes the mean velocity modulated by particles. The changing statistical velocity induced by particle modulation implies the effects of modulation of the local flow structures. This study is expected to be useful to the control of two-phase turbulent jets. 展开更多
关键词 large-eddy simulation particle-laden jet turbulence structures jet near-fields two-way coupling
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Transient growth in turbulent particle-laden channel flow 认领 引用 被引量：3
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作者 Yang Song Chunxiao Xu +1 位作者 Weixi Huang Lili Wang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2020年第1期1-11,共11页
Linear transient growth of optimal perturbations in particle-laden turbulent channel flow is investigated in this work.The problem is formulated in the framework of a Eulerian-Eulerian approach,employing two-way coupl... Linear transient growth of optimal perturbations in particle-laden turbulent channel flow is investigated in this work.The problem is formulated in the framework of a Eulerian-Eulerian approach,employing two-way coupling between fine particles and fluid flow.The model is first validated in laminar cases,after which the transient growth of coherent perturbations in turbulent channel flow is investigated,where the mean particle concentration distribution is obtained by direct numerical simulation.It is shown that the optimal small-scale structures for particles are streamwise streaks just below the optimal streamwise velocity streaks,as was previously found in numerical simulations of particle-laden channel flow.This indicates that the optimal growth of perturbations is a dominant mechanism for the distribution of particles in the near-wall region.The current study also considers the transient growth of small-and large-scale perturbations at relatively high Reynolds numbers,which reveals that the optimal large-scale structures for particles are in the near-wall region while the optimal large-scale structures for fluid enter the outer region. 展开更多
关键词 Optimal transient growth Wall turbulence Coherent structures Particle-laden turbulence
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Experimental Research on Dynamic Erosion of EPDM Insulation Subjected to Particle-Laden Flow 认领 引用 被引量：2
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作者 徐义华 胡春波 +1 位作者 张胜敏 陈剑 《Defence Technology（防务技术）》 CAS 2010年第4期225-233,共9页
The instantaneous degradation of erosion surface of ethylene propylene diene monomer(EPDM)insulation subjected to the particle-laden flow in two operating conditions was measured by using a real-time X-ray radiography... The instantaneous degradation of erosion surface of ethylene propylene diene monomer(EPDM)insulation subjected to the particle-laden flow in two operating conditions was measured by using a real-time X-ray radiography system.The images of its erosion state and dynamic ablation rate were obtained.And the charring-layer was analyzed by using SEM and energy spectrum.The experimental results indicate that the erosion rate of EPDM insulation layer impacted by low speed and low concentration particle flow is relatively small in the 1st second since the motor starting,but increases rapidly in 1 to 2.5 s,while the erosion rate of EPDM insulation layer impacted by high speed and high concentration particle flow increases rapidly in the 1st second;the ablation rate at the section eroded intensively by particle flow increases at first,then decreases,and goes to stabilization after 4.5 s;the higher speed and concentration particle flow are,the deeper particles get into charring layer,which lead to more thermal increment and thinner charring layer. 展开更多
关键词 propulsion system of aviation & aerospace particle-laden flow EPDM dynamic ablation charring layer
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On the hydrodynamic stability of a particle-laden flow in growing flat plate boundary layer 认领 引用 被引量：4
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作者 XIE Ming-liang LIN Jian-zhong XING Fu-tang 《Journal of Zhejiang University-SCIENCE A》 SCIE EI CAS 2007年第2期275-284,共10页
The parabolized stability equation (PSE) was derived to study the linear stability of particle-laden flow in growing Blasius boundary layer. The stability characteristics for various Stokes numbers and particle concen... The parabolized stability equation (PSE) was derived to study the linear stability of particle-laden flow in growing Blasius boundary layer. The stability characteristics for various Stokes numbers and particle concentrations were analyzed after solving the equation numerically using the perturbation method and finite difference. The inclusion of the nonparallel terms produces a reduction in the values of the critical Reynolds number compared with the parallel flow. There is a critical value for the effect of Stokes number, and the critical Stokes number being about unit, and the most efficient instability suppression takes place when Stokes number is of order 10. But the presence of the nonparallel terms does not affect the role of the particles in gas. That is, the addition of fine particles (Stokes number is much smaller than 1) reduces the critical Reynolds number while the addition of coarse particles (Stokes number is much larger than 1) enhances it. Qualitatively the effect of nonparallel mean flow is the same as that for the case of plane parallel flows. 展开更多
关键词 Hydrodynamic stability Blasius boundary layer Particle-laden nonparallel flow Numerical simulation
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Two-phase micro-and macro-time scales in particle-laden turbulent channel flows 认领 引用
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作者 Bing Wang Michael Manhart 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2012年第3期595-604,共10页
The micro- and macro-time scales in two-phase turbulent channel flows are investigated using the direct nu- merical simulation and the Lagrangian particle trajectory methods for the fluid- and the particle-phases, res... The micro- and macro-time scales in two-phase turbulent channel flows are investigated using the direct nu- merical simulation and the Lagrangian particle trajectory methods for the fluid- and the particle-phases, respectively. Lagrangian and Eulerian time scales of both phases are cal- culated using velocity correlation functions. Due to flow anisotropy, micro-time scales are not the same with the theo- retical estimations in large Reynolds number （isotropic） tur- bulence. Lagrangian macro-time scales of particle-phase and of fluid-phase seen by particles are both dependent on particle Stokes number. The fluid-phase Lagrangian inte- gral time scales increase with distance from the wall, longer than those time scales seen by particles. The Eulerian inte- gral macro-time scales increase in near-wall regions but de- crease in out-layer regions. The moving Eulerian time scales are also investigated and compared with Lagrangian integral time scales, and in good agreement with previous measure- ments and numerical predictions. For the fluid particles the micro Eulerian time scales are longer than the Lagrangian ones in the near wall regions, while away from the walls the micro Lagrangian time scales are longer. The Lagrangian integral time scales are longer than the Eulerian ones. The results are useful for further understanding two-phase flow physics and especially for constructing accurate prediction models of inertial particle dispersion. 展开更多
关键词 Micro-time scale Lagrangian integral timescale ~ Moving Eulerian time scale Particle-laden turbulentflow ~ Particle Stokes number Direct numerical simulation（DNS） Lagrangian trajectory method
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Interscale analysis of sediment clusters amid turbulence 认领 引用 被引量：1
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作者 Wai Hong Ronald Chan Ahmed Elnahhas +3 位作者 Hanul Hwang Lucy J.Brown Andrew J.Banko S.Balachandar 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2026年第1期73-80,共8页
Noncohesive particle clusters are identified and tracked in turbulent flows to determine the breakdown and time evolution of cluster statistics and their implications for interscale mass transfer,which has connections... Noncohesive particle clusters are identified and tracked in turbulent flows to determine the breakdown and time evolution of cluster statistics and their implications for interscale mass transfer,which has connections to the classical turbulent energy cascade and its mass cascade counterpart running in parallel.In particular,the formation and dynamics of sediment and larvae clusters are of interest to coral larvae settlement in coastal regions and particularly the resilience of green-gray coastal protection solutions.Analogous cluster behavior is relevant to cloud microphysics and precipitation initiation,radiation transport and light transmission through colloids and suspensions,heat and mass transfer in particle-laden flows,and viral and pollutant transmission.Following a comparison between various clustering techniques,we adopt a density-based cluster identification algorithm based on its simplicity and efficiency,where particles are clustered based on the number of neighboring particles in their individual spheres of influence.We establish parallels with lattice-based percolation theory,as evident in the power-law scaling of the cluster size distribution near the percolation threshold.The degree of discontinuity of the phase transition associated with this percolation threshold is observed to broaden with larger Stokes numbers and thereby large-scale clustering.The sensitivity of our findings to the employed clustering algorithm is discussed.A novel cluster tracking algorithm is deployed to determine the interscale transfer rate along the particle-number phase-space dimension via accounting of cluster breakup and merger events,extending previous work on the bubble breakup cascade beneath surface breaking waves.Our findings shed light on the interaction between particle clusters and their carrier turbulent flows,with an eye toward transport models incorporating cluster characteristics and dynamics. 展开更多
关键词 Particle-laden flows Particle-laden turbulence Sediment transport Computational fluid dynamics Multiphase turbulence Particle clustering Percolation theory
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Algorithms in a Robust Hybrid CFD-DEM Solver for Particle-Laden Flows 认领 引用 被引量：11
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作者 Heng Xiao Jin Sun 《Communications in Computational Physics》 SCIE 2011年第2期297-323,共27页
A robust and efficient solver coupling computational fluid dynamics(CFD)with discrete element method(DEM)is developed to simulate particle-laden flows in various physical settings.An interpolation algorithm suitable f... A robust and efficient solver coupling computational fluid dynamics(CFD)with discrete element method(DEM)is developed to simulate particle-laden flows in various physical settings.An interpolation algorithm suitable for unstructured meshes is proposed to translate between mesh-based Eulerian fields and particle-based Lagrangian quantities.The interpolation scheme reduces the mesh-dependence of the averaging and interpolation procedures.In addition,the fluid-particle interaction terms are treated semi-implicitly in this algorithm to improve stability and to maintain accuracy.Finally,it is demonstrated that sub-stepping is desirable for fluid-particle systems with small Stokes numbers.A momentum-conserving sub-stepping technique is introduced into the fluid-particle coupling procedure,so that problems with a wide range of time scales can be solved without resorting to excessively small time steps in the CFD solver.Several numerical examples are presented to demonstrate the capabilities of the solver and the merits of the algorithm. 展开更多
关键词 Fluid-particle interaction particle-laden flow discrete element method computational fluid dynamics hybrid model
REVIEW OF SOME RESEARCHES ON NANO-AND SUBMICRON BROWNIAN PARTICLE-LADEN TURBULENT FLOW 认领 引用 被引量：1
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作者 LIN Jian-zhong HUANG Li-zhong 《Journal of Hydrodynamics》 SCIE EI CSCD 2012年第6期801-808,共8页
The study of nano- and submicron Brownian particle-laden turbulent flow has wide industrial applicability and hence has received much attention. The purpose of the present paper is to provide and review some researche... The study of nano- and submicron Brownian particle-laden turbulent flow has wide industrial applicability and hence has received much attention. The purpose of the present paper is to provide and review some researches in this field. The topics are related to the universality, particularity, complexity and importance of nano- and submicron Brownian particle-laden turbulent flow, the models of particle general dynamical equation, the collision behavior of particles. Finally, several open research issues are identified. 展开更多
关键词 particle-laden flow nano-particle submicron particle Brownian turbulence
Numerical study of the near-wall vortical structures in particle-laden turbulent flow by a new vortex identification method-Liutex 认领 引用 被引量：3
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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
Effect of particle inertia on temperature statistics in particle-laden homogeneous isotropic turbulence 认领 引用 被引量：8
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作者 HE Zhu LIU Zhaohui +2 位作者 CHEN Sheng LIU Yaming ZHENG Chuguang 《Science China(Technological Sciences)》 CAS 2006年第2期210-221,共12页
The fluid temperature statistics along particle trajectories is crucial to under-stand the mechanisms of turbulent non-isothermal or reactive fluid-particle flow,especially for the Lagrangian model of non-isothermal p... The fluid temperature statistics along particle trajectories is crucial to under-stand the mechanisms of turbulent non-isothermal or reactive fluid-particle flow,especially for the Lagrangian model of non-isothermal particle-laden turbulent flow.In the present study,direct numerical simulations were utilized to generate temperature field statistics in particle-laden incompressible stationary homogeneous isotropic turbulent flows,which is focused on the effect of particle response time on the Lagrangian statistics of the particle and the fluid temperature seen by particles.It shows that,for the particles withτp/τk1),the trend is inversed.For small parti-cles(τp/τk<5),the Lagrangian autocorrelation coefficient of the particle temperature RpTdecreases as the particle inertia(τp/τk)increases.The trend is reversed for larger particles.The autocorrelation of fluid temperature along the particle path,RpfT,decreased as the particle inertia increased.And as the particle inertia increased,the autocorrelation coeffi-cient of the fluid temperature seen by particle decreased more rapidly than that of the particle temperature.The mean temperature gradient contributes to the correlation be-tween the particles velocity component and temperature fluctuations in the direction of the gradient.For the particles withτp/τk<1,the magnitude of the correlation coefficient in-creases as the particle inertia increases,while this value is independent of the particle time constant for larger particles. 展开更多
关键词 direct numerical simulation temperature statistics particle-laden turbulent flow Lagrangian statistics.
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Effect of Stokes number on energy modulation of the fluid in turbulent particle-laden channel flows 认领 引用 被引量：1
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作者 Zhi-feng Wu Jian-zhao Wu +1 位作者 Bo-fu Wang Zhi-ming Lu 《Journal of Hydrodynamics》 SCIE EI CSCD 2022年第3期510-521,共12页
The effect of Stokes number on the kinetic energy(KE)budget in particle-laden turbulent channel flows is examined by conducting two-way coupled direct numerical simulations using the Eulerian-Lagrangian approach.The f... The effect of Stokes number on the kinetic energy(KE)budget in particle-laden turbulent channel flows is examined by conducting two-way coupled direct numerical simulations using the Eulerian-Lagrangian approach.The friction Reynolds number of the single phase channel flow is Reτ=180,the particle mass loading and volume fraction areφm=0.2,φv≈10−4,and the Stokes numbers range from St+=14–92.The statistics show that due to the presence of solid particles,the mean velocity is reduced in the vicinity of the wall but enhanced in the outer region,and the off-streamwise intensity of fluctuated velocity and the Reynolds stress are reduced in the whole channel.The analysis on the budgets of turbulent kinetic energy(TKE)finds that the presence of particles induces a significant reduction on both the production and dissipation rates.With increasing Stokes number St+,both the production and dissipation rates exhibit non-monotonical trends,i.e.,both initially decrease for St+40.This suggests that the particle-induced suppression on TKE production and dissipation is the strongest nearly at St+=40.It is also found that particles act as an additional sink/source term in the budgets of both mean-flow kinetic energy(MKE)and TKE.In addition,we investigate the influence of St+on the“zero point”which indicates the balance of exchanging energy between the particle and fluid phases.It is shown that with increasing St+,the“zero point”moves toward the wall,suggesting that the position of perfect following between particle and fluid is closer to the wall with larger St+.The present results reveal the Stokes number effects on the spatial transport mechanisms of MKE,TKE in turbulent channel flows laden with inertial particles. 展开更多
关键词 Particle-laden flows two-way coupling Stokes numbers kinetic energy budgets
On Kelvin-Helmholtz instability of particulate two-fluid flow 认领 引用
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作者 C.Q.Ru 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2025年第4期41-52,共12页
A hydrodynamic model is used to study Kelvin-Helmholtz(KH)instability of the interface between two particle-laden inviscid fluids moving with two different uniform mean velocities.Explicit eigen-equation is derived to... A hydrodynamic model is used to study Kelvin-Helmholtz(KH)instability of the interface between two particle-laden inviscid fluids moving with two different uniform mean velocities.Explicit eigen-equation is derived to study the effect of suspended particles on the growth rate of KH instability.For dusty gases with negligible volume fraction of heavy particles and small particle-to-fluid mass ratio,the real and imaginary parts of leading-order asymptotic expression derived by the present model for the growth rate are shown to be identical to the earlier results derived by the classical Saffman model established for dusty gases.Beyond the known results,explicit leading-order asymptotic expressions for the effect of suspended particles on the growth rate are derived for several typical cases of basic interest.It is shown that the suspended particles can decrease or increase the growth rate of KH instability depending on the Stokes numbers of the particles and whether the particles are heavier or lighter than the clean fluid.Compared to the mass density of the clean fluid,our results based on leading-order asymptotic solutions show that heavier particles and lighter particles have opposite effects on the growth rate of KH instability,while the effect of neutrally buoyant particles on the growth rate of KH instability is negligible. 展开更多
关键词 Kelvin-Helmholtz Instability Particle-laden Particulate flow Inviscid
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Analysis of particle dispersion in a turbulent flow considering particle rotation 认领 引用 被引量：1
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作者 Wenshi Huang Yang Zhang +2 位作者 Yuxin Wu Jingyu Wang Minmin Zhou 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2023年第6期29-39,共11页
Non-spherical particles exist widely in natural and industrial fluid systems and the motions of nonspherical particles are significantly different from that of spherical particles.In this paper,a simplified model of n... Non-spherical particles exist widely in natural and industrial fluid systems and the motions of nonspherical particles are significantly different from that of spherical particles.In this paper,a simplified model of non-spherical particles considering particle drag correction,lift,and rotation was established.Based on the Eulerian-Lagrangian simulation,the dispersion characteristics of spherical and nonspherical particles with different Stokes numbers in a high-speed turbulent jet were analyzed and compared considering the effect of particle rotation.The results show that,the differences in particle dispersion and radial velocity fluctuation between non-spherical particles and spherical particles in the jet are significant,especially when Stokes number is large.Moreover,the effects of different type of forces on the dispersion of non-spherical particles and spherical particles were compared in detail,which revealed that the change of the Magnus force caused by the increase in the angular velocity of non-spherical particles plays a dominant role in the differences of particle dispersion. 展开更多
关键词 Dispersion Particle Particle-laden flows Particle rotation Turbulent flow
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A Novel Lattice Boltzmann Model For Reactive Flows with Fast Chemistry 认领 引用 被引量：1
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作者 陈胜 柳朝晖 +4 位作者 贺铸 张超 田智威 施保昌 郑楚光 《Chinese Physics Letters》 SCIE EI CAS 2006年第3期656-659,共4页
A novel lattice Boltzmann model, in which we take the ratio of temperature difference in the temperature field to the environment one to be more than one order of magnitude than before, is developed to simulate two-di... A novel lattice Boltzmann model, in which we take the ratio of temperature difference in the temperature field to the environment one to be more than one order of magnitude than before, is developed to simulate two-dimensional reactive flows with fast chemistry. Different from the hybrid scheme for reactive flows [Comput. Phys. Commun. 129 （2000）267], this scheme is strictly in a pure lattice Doltzmann style （i.e., we solve the flow, temperature, and concentration fields using the lattice Boltzmann method only）. Different from the recent non-coupled lattice Boltzmann scheme lint. J. Mod. Phys. B 17（2003）197], the fluid density in our model is coupled directly with the temperature. Excellent agreement between the present results and other numerical data shows that this scheme is an efficient numerical method for practical reactive flows with fast chemistry. 展开更多
关键词 MACH NUMBER COMBUSTION PARTICLE-LADEN FLOW NEWTONIAN FLUID POROUS-MEDIA SIMULATION EQUATION SCHEME
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Alignment of inertialess spheroidal particles in flow-structure-dominated regions of turbulent channel flow:shape effect 认领 引用 被引量：3
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作者 Zhiwen Cui Lihao Zhao 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2024年第8期45-66,共22页
The alignment of elongated fibers and thin disks is known to be significantly influenced by the presence of fluid coherent structures in near-wall turbulence(Cui et al.2021).However,this earlier study is confined to t... The alignment of elongated fibers and thin disks is known to be significantly influenced by the presence of fluid coherent structures in near-wall turbulence(Cui et al.2021).However,this earlier study is confined to the spheroids with infinitely large or small aspect ratio,and the shape effect of finite aspect ratio on the alignment is not considered.The current study investigates the shape-dependent alignment of inertialess spheroids in structure-dominated regions of channel flow.With utilizing an ensemble-averaged approach for identifying the structure-dominated regions,we analyze the eigensystem of the linear term matrix in the Jeffery equation,which is governed by both particle shape and local fluid velocity gradients.In contrast to earlier conventional analysis based on local vorticity and strain rate,our findings demonstrate that the eigensystem of the Jeffery equation offers a convenient,effective,and universal framework for predicting the alignment behavior of inertialess spheroids in turbulent flows.By leveraging the eigensystem of the Jeffery equation,we uncover a diverse effect of fluid coherent structures on spheroid alignment with different particle shapes.Furthermore,we provide explanations for both shape-independent alignments observed in vortical-core regions and shape-dependent alignments around near-wall streamwise vortices. 展开更多
关键词 Non-spherical particle Direct numerical simulation Wall turbulence Particle-laden flow
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Particle modulations to turbulence in two-phase round jets 认领 引用 被引量：1
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作者 Bing Wang Huiqiang Zhang +2 位作者 Yi Liu Xiaofen Yan Xilin Wang 《Acta Mechanica Sinica》 SCIE EI CAS 2009年第5期611-617,共7页
The particle modulations to turbulence in round jets were experimentally studied by means of two-phase velocity measurements with Phase Doppler Anemometer(PDA).Laden with very large particles,no significant attenuatio... The particle modulations to turbulence in round jets were experimentally studied by means of two-phase velocity measurements with Phase Doppler Anemometer(PDA).Laden with very large particles,no significant attenuations of turbulence intensities were measured in the farfields,due to small two-phase slip velocities and particle Reynolds number.The gas-phase turbulence is enhanced by particles in the near-fields,but it is significantly attenuated by the small particles in the far-fields.The smaller particles have a more profound effect on the attenuation of turbulence intensities.The enhancements or attenuations of turbulence intensities in the far-fields depends on the energy production,transport and dissipation mechanisms between the two phases,which are determined by the particle prop-erties and two-phase velocity slips.The non-dimensional parameter CTI is introduced to represent the change of turbulence intensity. 展开更多
关键词 Particle modulations Turbulence intensity Particle sizes Two-phase slip velocity Particle-laden round turbulent jet
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Rotational dynamics of bottom-heavy rods in turbulence from experiments and numerical simulations 认领 引用 被引量：1
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作者 Linfeng Jiang Cheng Wang +2 位作者 Shuang Liu Chao Sun Enrico Calzavarini 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2021年第1期26-31,共6页
We successfully perform the three-dimensional tracking in a turbulent fluid flow of small axisymmetrical particles that are neutrally-buoyant and bottom-heavy,i.e.,they have a non-homogeneous mass distribu-tion along ... We successfully perform the three-dimensional tracking in a turbulent fluid flow of small axisymmetrical particles that are neutrally-buoyant and bottom-heavy,i.e.,they have a non-homogeneous mass distribu-tion along their symmetry axis.We experimentally show how a tiny mass inhomogeneity can affect the particle orientation along the preferred vertical direction and modify its tumbling rate.The experiment is complemented by a series of simulations based on realistic Navier-Stokes turbulence and on a point-like particle model that is capable to explore the full range of parameter space characterized by the gravi-tational torque stability number and by the particle aspect ratio.We propose a theoretical perturbative prediction valid in the high bottom-heaviness regime that agrees well with the observed preferential ori-entation and tumbling rate of the particles.We also show that the heavy-tail shape of the probability distribution function of the tumbling rate is weakly affected by the bottom-heaviness of the particles. 展开更多
关键词 Particle-laden flows Turbulent flows Direct numerical simulations Particle tracking
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The influence of sub-grid scale motions on particle collision in homogeneous isotropic turbulence 认领 引用 被引量：1
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作者 Yan Xiong Jing Li +1 位作者 Zhaohui Liu Chuguang Zheng 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2018年第1期22-36,共15页
The absence of sub-grid scale(SGS) motions leads to severe errors in particle pair dynamics, which represents a great challenge to the large eddy simulation of particle-laden turbulent flow. In order to address this i... The absence of sub-grid scale(SGS) motions leads to severe errors in particle pair dynamics, which represents a great challenge to the large eddy simulation of particle-laden turbulent flow. In order to address this issue,data from direct numerical simulation(DNS) of homogenous isotropic turbulence coupled with Lagrangian particle tracking are used as a benchmark to evaluate the corresponding results of filtered DNS(FDNS). It is found that the filtering process in FDNS will lead to a non-monotonic variation of the particle collision statistics, including radial distribution function, radial relative velocity, and the collision kernel. The peak of radial distribution function shifts to the large-inertia region due to the lack of SGS motions, and the analysis of the local flowstructure characteristic variable at particle position indicates that the most effective interaction scale between particles and fluid eddies is increased in FDNS. Moreover,this scale shifting has an obvious effect on the odd-order moments of the probability density function of radial relative velocity, i.e. the skewness, which exhibits a strong correlation to the variance of radial distribution function in FDNS.As a whole, the radial distribution function, together with radial relative velocity, can compensate the SGS effects for the collision kernel in FDNS when the Stokes number based on the Kolmogorov time scale is greater than 3.0. However,it still leaves considerable errors for St< 3.0. 展开更多
关键词 Particle-laden turbulence Homogenous isotropic turbulence Large eddy simulation Particle collisions
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