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Large-eddy simulations of oscillatory flow around a cylinder at high Keulegan-Carpenter and Reynolds numbers 认领 引用
1
作者 Shaoshi Dai Dan Tang +1 位作者 Bassam A.Younis Chengwang Xiong 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2026年第5期134-148,共15页
Large-eddy simulation based on a newly developed wall-adaptive local eddy-viscosity model is used to study the viscous oscillatory flow around a cylinder at high Keulegan-Carpenter(KC)and Reynolds(Re)numbers.The effic... Large-eddy simulation based on a newly developed wall-adaptive local eddy-viscosity model is used to study the viscous oscillatory flow around a cylinder at high Keulegan-Carpenter(KC)and Reynolds(Re)numbers.The efficacy of the new model,which was implemented in OpenFOAM,was first checked via simulations of a standard benchmark flow,namely that around a single cylinder in oscillatory flow at Re-600 and KC-2.08.These simulations accurately captured the Honj vortices observed in the measurements of Honji.Thereafter,simulations were performed for values of KC in the range 1.67≤KC≤66.7,where it was found that the evolution of the Honji vortices and streaked flow is influenced by the interactions that occur between the outer oscillation flow and the inner separated boundary layer.Further,it was found that these interactions are strongly dependent on this parameter,as are all the dimensionless coefficients for both the mean and fluctuating components of the hydrodynamic forces.At low values of KC and Re,frequency doubling resonance between the vortex shedding(fvo)and that of the oscillatory flow(fos)was observed.A new empirical relationship between fvo/fos,KC and Re is proposed. 展开更多
关键词 Large-eddy simulation Oscillatory flow Vortex shedding Hydrodynamic forces
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Quantum-enriched large-eddy simulation with the incompressible Schrodinger flow 认领 引用 被引量：2
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作者 Zishuo Han Yue Yang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2025年第1期95-105,共11页
We propose a hybrid quantum-classical method,the quantum-enriched large eddy simulation(QELES),for simulating turbulence.The QELES combines the large-scale motion of the large eddy simulation(LES)and the subgrid motio... We propose a hybrid quantum-classical method,the quantum-enriched large eddy simulation(QELES),for simulating turbulence.The QELES combines the large-scale motion of the large eddy simulation(LES)and the subgrid motion of the incompressible Schrodinger flow(ISF).The ISF is a possible way to be simulated on a quantum computer,and it generates subgrid scale turbu-lent structures to enrich the LES field.The enriched LES field can be further used in turbulent combustion and multi-phase flows in which the subgrid scale motion plays an important role.As a conceptual study,we perform the simulations of ISF and LES separately on a classical computer to simulate decaying homogeneous isotropic turbulence.Then,the QEI ES velocity is obtained by the time matching and the spectral blending methods.The QEL ES achieves significant improvement in predicting the energy spectrum,probaility density functions of velocity and vorticity components,and velocity structure functions,and reconstructs coherent small-scales vortices in the direct numerical simulation(DNS).On the other hand,the vortices in the QELES are less elongated and tangled than those in the DNS,and the magnitude of the third-order structure function in the QELES is less than that in the DNS,due to the diferent constitutive relations in the viscous flow and ISE. 展开更多
关键词 Quantum computing Large-eddy simulation Subgrid motion
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Wall-modeling for large-eddy simulation of flows around an axisymmetric body using the diffuse-interface immersed boundary method 认领 引用 被引量：13
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作者 Beiji SHI Xiaolei YANG +2 位作者 Guodong JIN Guowei HE Shizhao WANG 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2019年第3期305-320,共16页
A novel method is proposed to combine the wall-modeled large-eddy simulation(LES) with the diffuse-interface direct-forcing immersed boundary(IB) method.The new developments in this method include:(i) the momentum equ... A novel method is proposed to combine the wall-modeled large-eddy simulation(LES) with the diffuse-interface direct-forcing immersed boundary(IB) method.The new developments in this method include:(i) the momentum equation is integrated along the wall-normal direction to link the tangential component of the effective body force for the IB method to the wall shear stress predicted by the wall model;(ii) a set of Lagrangian points near the wall are introduced to compute the normal component of the effective body force for the IB method by reconstructing the normal component of the velocity. This novel method will be a classical direct-forcing IB method if the grid is fine enough to resolve the flow near the wall. The method is used to simulate the flows around the DARPA SUBOFF model. The results obtained are well comparable to the measured experimental data and wall-resolved LES results. 展开更多
关键词 wall model large-eddy simulation(LES) immersed boundary(IB)method diffuse-interface
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Large-eddy simulation of shock-wave/turbulent boundary layer interaction with and without Spark Jet control 认领 引用 被引量：12
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作者 Yang Guang Yao Yufeng +3 位作者 Fang Jian Gan Tian Li Qiushi Lu Lipeng 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2016年第3期617-629,共13页
The efficiency and mechanism of an active control device ＂＇Spark Jet＂ and its application in shock-induced separation control are studied using large-eddy simulation in this paper. The base flow is the interaction ... The efficiency and mechanism of an active control device ＂＇Spark Jet＂ and its application in shock-induced separation control are studied using large-eddy simulation in this paper. The base flow is the interaction of an oblique shock-wave generated by 8° wedge and a spatially-developing Ma = 2.3 turbulent boundary layer. The Reynolds number based on the incoming flow property and the boundary layer displacement thickness at the impinging point without shock-wave is 20000. The detailed numerical approaches were presented. The inflow turbulence was generated using the digital filter method to avoid artificial temporal or streamwise periodicity. The , merical results including velocity profile, Reynolds stress profile, skin friction, and wall pressure were sys- tematically validated against the available wind tunnel particle image velocimetry （PIV） measure- ments of the same flow condition. Further study on the control of flow separation due to the strong shock-viscous interaction using an active control actuator ＂＇Spark Jet＇＂ was conducted. The single-pulsed characteristic of the device was obtained and compared with the experiment. Both instantaneous and time-averaged flow fields have shown that the jet flow issuing from the actuator cavity enhances the flow mixing inside the boundary layer, making the boundary layer more resis- tant to flow separation. Skin friction coefficient distribution shows that the separation bubble length is reduced by about 35% with control exerted. 展开更多
关键词 Large-eddy simulation Shock-wave：Turbulent boundary layer Interaction Spark Jet control
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The Probability Density Function Related to Shallow Cumulus Entrainment Rate and Its Influencing Factors in a Large-Eddy Simulation 认领 引用 被引量：5
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作者 Lei ZHU Chunsong LU +5 位作者 Xiaoqi XU Xin HE Junjun LI Shi LUO Yuan WANG Fan WANG 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第1期173-187,共15页
The process of entrainment-mixing between cumulus clouds and the ambient air is important for the development of cumulus clouds.Accurately obtaining the entrainment rate(λ)is particularly important for its parameteri... The process of entrainment-mixing between cumulus clouds and the ambient air is important for the development of cumulus clouds.Accurately obtaining the entrainment rate(λ)is particularly important for its parameterization within the overall cumulus parameterization scheme.In this study,an improved bulk-plume method is proposed by solving the equations of two conserved variables simultaneously to calculateλof cumulus clouds in a large-eddy simulation.The results demonstrate that the improved bulk-plume method is more reliable than the traditional bulk-plume method,becauseλ,as calculated from the improved method,falls within the range ofλvalues obtained from the traditional method using different conserved variables.The probability density functions ofλfor all data,different times,and different heights can be well-fitted by a log-normal distribution,which supports the assumed stochastic entrainment process in previous studies.Further analysis demonstrate that the relationship betweenλand the vertical velocity is better than other thermodynamic/dynamical properties;thus,the vertical velocity is recommended as the primary influencing factor for the parameterization ofλin the future.The results of this study enhance the theoretical understanding ofλand its influencing factors and shed new light on the development ofλparameterization. 展开更多
关键词 large-eddy simulation cumulus clouds entrainment rate probability density functions spatial and temporal distribution
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Recent improvements of actuator line-large-eddy simulation method for wind turbine wakes 认领 引用 被引量：5
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作者 Zhiteng GAO Ye LI +2 位作者 Tongguang WANG Shitang KE Deshun LI 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2021年第4期511-526,共16页
In a large wind farm,the wakes of upstream and downstream wind turbines can interfere with each other,affecting the overall power output of the wind farm.To further improve the numerical accuracy of the turbine wake d... In a large wind farm,the wakes of upstream and downstream wind turbines can interfere with each other,affecting the overall power output of the wind farm.To further improve the numerical accuracy of the turbine wake dynamics under atmosphere turbulence,this work proposes some improvements to the actuator line-large-eddy simulation(AL-LES)method.Based on the dynamic k-equation large-eddy simulation(LES),this method uses a precursor method to generate atmospheric inflow turbulence,models the tower and nacelle wakes,and improves the body force projection method based on an anisotropic Gaussian distribution function.For these three improvements,three wind tunnel experiments are used to validate the numerical accuracy of this method.The results show that the numerical results calculated in the far-wake region can reflect the characteristics of typical onshore and offshore wind conditions compared with the experimental results.After modeling the tower and nacelle wakes,the wake velocity distribution is consistent with the experimental result.The radial migration velocity of the tip vortex calculated by the improved blade body force distribution model is 0.32 m/s,which is about 6%different from the experimental value and improves the prediction accuracy of the tip vortex radial movement.The method proposed in this paper is very helpful for wind turbine wake dynamic analysis and wind farm power prediction. 展开更多
关键词 actuator line(AL)method large-eddy simulation(LES) wake tip vortex wind turbine
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Evaluation of Subgrid-scale Models in Large-eddy Simulations of Turbulent Flow in a Centrifugal Pump Impeller 认领 引用 被引量：17
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作者 YANG Zhengjun WANG Fujun ZHOU Peijian 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2012年第5期911-918,共8页
The current research of large eddy simulation （LES） of turbulent flow in pumps mainly concentrates in applying conventional subgrid-scale （SGS） model to simulate turbulent flow, which aims at obtaining the flow fi... The current research of large eddy simulation （LES） of turbulent flow in pumps mainly concentrates in applying conventional subgrid-scale （SGS） model to simulate turbulent flow, which aims at obtaining the flow field in pump. The selection of SGS model is usually not considered seriously, so the accuracy and efficiency of the simulation cannot be ensured. Three SGS models including Smagorinsky-Lilly model, dynamic Smagorinsky model and dynamic mixed model are comparably studied by using the commercial CFD code Fluent combined with its user define function. The simulations are performed for the turbulent flow in a centrifugal pump impeller. The simulation results indicate that the mean flows predicted by the three SGS models agree well with the experimental data obtained from the test that detailed measurements of the flow inside the rotating passages of a six-bladed shrouded centrifugal pump impeller performed using particle image velocimetry （PIV） and laser Doppler velocimetry （LDV）. The comparable results show that dynamic mixed model gives the most accurate results for mean flow in the centrifugal pump impeller. The SGS stress of dynamic mixed model is decompose into the scale similar part and the eddy viscous part. The scale similar part of SGS stress plays a significant role in high curvature regions, such as the leading edge and training edge of pump blade. It is also found that the dynamic mixed model is more adaptive to compute turbulence in the pump impeller. The research results presented is useful to improve the computational accuracy and efficiency of LES for centrifugal pumps, and provide important reference for carrying out simulation in similar fluid machineries. 展开更多
关键词 large-eddy simulation subgrid-scale model dynamic mixed model centrifugal pump
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Scaling law of resolved-scale isotropic turbulence and its application in large-eddy simulation 认领 引用 被引量：6
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作者 Le Fang Bo Li Li-Peng Lu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2014年第3期339-350,共12页
Eddy-damping quasinormal Markovian(EDQNM)theory is employed to calculate the resolved-scale spectrum and transfer spectrum,based on which we investigate the resolved-scale scaling law.Results show that the scaling law... Eddy-damping quasinormal Markovian(EDQNM)theory is employed to calculate the resolved-scale spectrum and transfer spectrum,based on which we investigate the resolved-scale scaling law.Results show that the scaling law of the resolved-scale turbulence,which is affected by several factors,is far from that of the full-scale turbulence and should be corrected.These results are then applied to an existing subgrid model to improve its performance.A series of simulations are performed to verify the necessity of a fixed scaling law in the subgrid modeling. 展开更多
关键词 Scaling law Large-eddy simulation CZZSmodel
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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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Advances in Large-eddy Simulation of Two-phase Combustion (I) LES of Spray Combustion 认领 引用 被引量：5
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作者 周力行 李科 王方 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2012年第2期205-211,共7页
Spray combustion is widely used in power, transportation, chemical and metallurgical, iron and steel making, aeronautical and astronautical engineering. In recent years, large-eddy simulation (LES) becomes more and mo... Spray combustion is widely used in power, transportation, chemical and metallurgical, iron and steel making, aeronautical and astronautical engineering. In recent years, large-eddy simulation (LES) becomes more and more attractive, because it can give the instantaneous flow and flame structures, and may give more accurate statistical results than the Reynolds averaged Navier-Stokes (RANS) modeling. In this paper, the present status of the studies on LES of spray combustion is reviewed, and the future research needs are discussed. 展开更多
关键词 spray combustion large-eddy simulation sub-gnd scale model
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Large-eddy simulation for the aero-vibro-acoustic analysis:plate-cavity system excited by turbulent channel flow 认领 引用 被引量：3
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作者 Lixing Zhu Ting Wu Guowei He 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2022年第10期38-55,共18页
The large-eddy simulation(LES)with the dynamic Smagorinsky model is used to predict the interior sound of an idealized vehicle cabin under the excitation of the wall pressures from turbulent channel flows.In compariso... The large-eddy simulation(LES)with the dynamic Smagorinsky model is used to predict the interior sound of an idealized vehicle cabin under the excitation of the wall pressures from turbulent channel flows.In comparison with direct numerical simulation(DNS),the LES results overpredict the sound pressure level(SPL)at low frequencies and underpredict the SPL at high frequencies.The incorrect predictions result from the incorrect prediction of LES on surface pressures,where the LES over-estimates the wavenumber and frequencies spectra of surface pressures at small wavenumbers and frequencies and under-estimates the spectra at large wavenumbers and frequencies.However,the LES results are close to the filtered-DNS results,implying that the unresolved scales are also important to surface pressures and interior sound.The Euler-Bernoulli beam under the excitation of exterior pressures,which serves as a simple model for aero-vibro-acoustics in the case of hydrodynamical fast,is used to explain the observed predictions and show that the Corcos model cannot represent the variation of turbulence pressure spectra at wavenumbers and frequencies.Therefore,the new requirement for the LES method,when applied to fluid-structural-acoustic interaction problems at high Reynolds numbers,is the correct prediction of wavenumber and frequency spectra of turbulence wall pressure. 展开更多
关键词 Large-eddy simulation Turbulent flow Aero-vibro-acoustics Surface pressure
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Large-eddy simulations of a forced homogeneous isotropic turbulence with polymer additives 认领 引用 被引量：3
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作者 王璐 蔡伟华 李凤臣 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第3期348-360,共13页
Large-eddy simulations （LES） based on the temporal approximate deconvolution model were performed for a forced homogeneous isotropic turbulence （FHIT） with polymer additives at moderate Taylor Reynolds number. Fin... Large-eddy simulations （LES） based on the temporal approximate deconvolution model were performed for a forced homogeneous isotropic turbulence （FHIT） with polymer additives at moderate Taylor Reynolds number. Finitely extensible nonlinear elastic in the Peterlin approximation model was adopted as the constitutive equation for the filtered conformation tensor of the polymer molecules. The LES results were verified through comparisons with the direct numerical simulation results. Using the LES database of the FHIT in the Newtonian fluid and the polymer solution flows, the polymer effects on some important parameters such as strain, vorticity, drag reduction, and so forth were studied. By extracting the vortex structures and exploring the flatness factor through a high-order correlation function of velocity derivative and wavelet analysis, it can be found that the small-scale vortex structures and small-scale intermittency in the FHIT are all inhibited due to the existence of the polymers. The extended self-similarity scaling law in the polymer solution flow shows no apparent difference from that in the Newtonian fluid flow at the currently simulated ranges of Reynolds and Weissenberg numbers. 展开更多
关键词 forced homogeneous isotropic turbulence polymer additives large-eddy simulation temporal ap-proximate deconvolution model
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Large-eddy simulation of fluid mixing in tee with sintered porous medium 认领 引用 被引量：2
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作者 王永伟 卢涛 +2 位作者 姜培学 程鹏飞 王奎生 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2012年第7期911-922,共12页
Mixing processes of hot and cold fluids in a tee with and without sin- tered copper spheres are simulated by FLUENT using the large-eddy simulation （LES） turbulent flow model and the sub-grid scale （SGS） Smagorins... Mixing processes of hot and cold fluids in a tee with and without sin- tered copper spheres are simulated by FLUENT using the large-eddy simulation （LES） turbulent flow model and the sub-grid scale （SGS） Smagorinsky-Lilly （SL） model with buoyancy. Comparisons of numerical results of the two cases with and without sintered copper spheres show that the porous medium significantly reduces velocity and temper- ature fluctuations because the porous medium can effectively restrict the fluid flow and enhance heat transfer. The porous medium obviously increases the pressure drop in the main duct. The porous medium reduces the power spectrum density （PSD） of tempera- ture fluctuations in the frequency range from 1 Hz to 10 Hz. 展开更多
关键词 large-eddy simulation mixing tee sintered porous medium
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Large-eddy Simulation of Bubble-Liquid Confined Jets 认领 引用 被引量：4
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作者 杨玟 周力行 L.S.Fan 《Chinese Journal of Chemical Engineering》 SCIE EI CAS 2002年第4期381-384,共4页
The Large-eddy simulation (LES) with two-way coupling is used to study bubble-liquid two-phase confined multiple jets discharged into a 2D channel.The LES results reveal the large-eddy vortex structures of both liquid... The Large-eddy simulation (LES) with two-way coupling is used to study bubble-liquid two-phase confined multiple jets discharged into a 2D channel.The LES results reveal the large-eddy vortex structures of both liquid flow and bubble motion,the shear-generated and bubble-induced liquid turbulence,and indicate much stronger bubble fluctuation than that of the liquid,the enhancement of liquid turbulence by bubbles.Both shear and bubble-liquid interaction are important for the liquid turbulence generation in the case studied. 展开更多
关键词 large-eddy simulation bubble-liquid flow two-phase jet
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Large-eddy Simulation of Fluid Flow and Heat Transfer in a Mixing Tee Junction 认领 引用 被引量：2
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作者 LU Tao WANG Yongwei WANG Kuisheng 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2012年第6期1144-1150,共7页
The temperature fluctuation caused by thermal striping phenomena of hot and cold fluids mixing results in cyclical thermal stress fatigue failure of the pipe wall. Mean temperature difference between hot and cold flui... The temperature fluctuation caused by thermal striping phenomena of hot and cold fluids mixing results in cyclical thermal stress fatigue failure of the pipe wall. Mean temperature difference between hot and cold fluids was often used as thermal load in previous analysis of thermal fatigue failure, thereby the influences of the amplitude and frequency of temperature fluctuation on thermal fatigue failure were neglected. Based on the mechanism of flow and heat transfer which induces thermal fatigue, the turbulent mixing of hot and cold water in a tee junction is simulated with FLUENT platform by using the Large-eddy simulation（LES） turbulent flow model with the sub-grid scale（SGS） model of Smagorinsky-Lilly（SL） to capture the amplitude and frequency of temperature fluctuation. In a simulation case, hot water with temperature of 343.48 K and velocity of 0.15 m/s enters the horizontal main duct with the side length of 100 mm, while cold water with temperature of 296.78 K and velocity of 0.3 m/s enters the vertical branch duct with the side length of 50 mm. The numerical results show that the mean and fluctuating temperatures are in good agreement with the previous experimental data, which describes numerical simulation with high reliability and accuracy; the power spectrum density（PSD） on top wall is higher than that on bottom wall（as the frequency less than 1 Hz）, while the PSD on bottom wall is relatively higher than that on top wall （as the frequency of 1-10Hz）. The temperature fluctuations in full mixing region of the tee junction can be accurately captured by LES and can provide the theoretical basis for the thermal stress and thermal fatigue analyses. 展开更多
关键词 Large-eddy simulation flow heat transfer tee junction
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Large-eddy Simulation of Ethanol Spray-Air Combustion and Its Experimental Validation 认领 引用 被引量：2
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作者 李科 周力行 CHAN C.K 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2014年第2期214-220,共7页
Large-eddy simulation of spray combustion is under its rapid development.Different combustion models were used by different investigators.However,these models are less validated by detailed experimental data.In this p... Large-eddy simulation of spray combustion is under its rapid development.Different combustion models were used by different investigators.However,these models are less validated by detailed experimental data.In this paper,large-eddy simulation(LES)of ethanol spray-air combustion was made using an Eulerian-Lagrangian approach,a subgrid-scale kinetic energy stress model,and a filtered finite-rate combustion model,neglecting the sub-grid scale reaction rate.The simulation results are compared with experimental dada in the literature and validated in detail.The LES obtained statistically averaged gas temperature is in much better agreement with the experimental results than Reynolds averaged(RANS)modeling using the most complex probability density function(PDF)equation combustion model.The instantaneous LES results show the coherent structures of the shear region near the high-temperature flame zone and the fuel vapor concentration map,indicating that the droplets are concentrated in this shear region.The instantaneous temperature,oxygen and carbon dioxide concentration maps show the close interaction between the coherent structures and the combustion reaction. 展开更多
关键词 ethanol-air two-phase flow spray combustion large-eddy simulation
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Investigation of flow characteristics in a rotor-stator cavity under crossflow using wall-modelled large-eddy simulation 认领 引用 被引量：1
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作者 Lei XIE Qiang DU +3 位作者 Guang LIU Zengyan LIAN Yaguang XIE Yifu LUO 《Journal of Zhejiang University-SCIENCE A》 SCIE EI CAS CSCD 2023年第6期473-496,共24页
Rotor-stator cavities are frequently encountered in engineering applications such as gas turbine engines.They are usually subject to an external hot mainstream crossflow which in general is highly swirled under the ef... Rotor-stator cavities are frequently encountered in engineering applications such as gas turbine engines.They are usually subject to an external hot mainstream crossflow which in general is highly swirled under the effect of the nozzle guide vanes.To avoid hot mainstream gas ingress,the cavity is usually purged by a stream of sealing flow.The interactions between the external crossflow,cavity flow,and sealing flow are complicated and involve all scales of turbulent unsteadiness and flow instability which are beyond the resolution of the Reynolds-average approach.To cope with such a complex issue,a wall-modeled large-eddy simulation(WMLES)approach is adopted in this study.In the simulation,a 20°sector model is used and subjected to a uniform pre-swirled external crossflow and a stream of radial sealing flow.It is triggered by a convergent Reynoldsaveraged Navier-Stokes(RANS)result in which the shear stress transport(SST)turbulent model is used.In the WMLES simulation,the Smagoringsky sub-grid scale(SGS)model is applied.A scalar transportation equation is solved to simulate the blending and transportation process in the cavity.The overall flow field characteristics and deviation between RANS and WMLES results are discussed first.Both RANS and WMLES results show a Batchelor flow mode,while distinct deviation is also observed.Deviations in the small-radius region are caused by the insufficiency of the RANS approach in capturing the small-scale vortex structures in the boundary layer while deviations in the large-radius region are caused by the insufficiency of the RANS approach in predicting the external crossflow ingestion.The boundary layer vortex and external ingestion are then discussed in detail,highlighting the related flow instabilities.Finally,the large-flow structures induced by external flow ingress are analyzed using unsteady pressure oscillation signals. 展开更多
关键词 Wall-modeled large-eddy simulation(WMLES) Rotor-stator cavity Flow instability Reynolds-averaged Navier-Stokes(RANS)
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LARGE-EDDY SIMULATION OF TWO-PHASE REACTING FLOW IN MODEL COMBUSTOR 认领 引用 被引量：2
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作者 颜应文 赵坚行 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2005年第1期1-8,共8页
The gas-droplet two-phase reacting flow in a model combustor with the V-gutter flame holder is studied by an Eulerian-Lagrangian large-eddy simulation (LES) approach. The k-equation subgrid-scale model is used to simu... The gas-droplet two-phase reacting flow in a model combustor with the V-gutter flame holder is studied by an Eulerian-Lagrangian large-eddy simulation (LES) approach. The k-equation subgrid-scale model is used to simulate the subgrid eddy viscosity, and the eddy-break-up (EBU) combustion subgrid-scale model is used to determine the chemical reaction rate. A two-step turbulent combustion subgrid-scale model is employed for calculating carbon monoxide CO concentration, and the NO subgrid-scale pollutant formation model for the evaluation of the rate of NO formation. The heat flux model is applied to the prediction of radiant heat transfer. The gas phase is solved with the SIMPLE algorithm and a hybrid scheme in the staggered grid system. The liquid phase equations are solved in a Lagrangian frame in reference of the particle-source-in-cell (PSIC) algorithm. From simulation results, the exchange of mass, moment and energy between gas and particle fields for the reacting flow in the afterburner with a V-gutter flame holder can be obtained. By the comparison of experimental and simulation results, profile temperature and pollutant of the outlet are quite in agreement with experimental data. Results show that the LES approach for predicting the two-phase instantaneous reacting flow and pollutant emissions in the afterburner is feasible. 展开更多
关键词 two-phase reacting flow large-eddy simulation pollutant emission afterburner
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A study of a supersonic capsule/rigid disk-gap-band parachute system using large-eddy simulation 认领 引用 被引量：1
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作者 Sheng GONG Chuijie WU 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2021年第4期485-500,共16页
The aerodynamic performances and flow features of the capsuleigid disk-gap-band(DGB)parachute system from the Mach number 1.8 to 2.2 are studied.We use the adaptive mesh refinement(AMR),the hybrid tuned center-differe... The aerodynamic performances and flow features of the capsuleigid disk-gap-band(DGB)parachute system from the Mach number 1.8 to 2.2 are studied.We use the adaptive mesh refinement(AMR),the hybrid tuned center-difference and weighted essentially non-oscillatory(TCD-WENO)scheme,and the large-eddy simulation(LES)with the stretched-vortex subgrid model.The simulations reproduce complex interaction of the flow structures,including turbulent wakes and bow shocks,as well as bow shocks and expansion waves.The results show that the calculated aerodynamic drag coefficient agrees well with the previou simulation.Both the aerodynamic drag coefficient and the aerodynamic drag oscillation of the parachute system decrease with the increase of the initial Mach number of the fluid.It is found that the position and angle of the bow shock ahead of the canopy change as the Mach number increases,which makes the flow inside the canopy and the turbulent wake behind the canopy more complex and unstable. 展开更多
关键词 compressible flow adaptive mesh refinement(AMR) large-eddy simulation(LES) supersonic flow rigid disk-gap-band(DGB)parachute
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Large-eddy structures of turbulent swirling flows and methane-air swirling diffusion combustion 认领 引用 被引量：4
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作者 Liyuan Hu Lixing Zhou Jian Zhang 《Acta Mechanica Sinica》 SCIE EI CAS 2005年第5期419-424,共6页
Turbulent swirling flows and methane-air swirling diffusion combustion are studied by large-eddy simulation （LES） using a Smagorinsky-Lilly subgrid scale turbulence model and a second-order moment （SOM） SGS combus... Turbulent swirling flows and methane-air swirling diffusion combustion are studied by large-eddy simulation （LES） using a Smagorinsky-Lilly subgrid scale turbulence model and a second-order moment （SOM） SGS combustion model, and also by RANS modeling using the Reynolds Stress equation model with the IPCM＋wall and IPCM pressure-strain models and SOM combustion model. The LES statistical results for swirling flows give good agreement with the experimental results, indicating that the adopted subgrid-scale turbulence model is suitable for swirling flows. The LES instantaneous results show the complex vortex shedding pattern in swirling flows. The initially formed large vortex structures soon break up in swirling flows. The LES statistical results of combustion modeling are near the experimental results and are as good as the RANS-SOM modeling results. The LES results show that the size and range of large vortex structures in swirling combustion are different from those of isothermal swirling flows, and the chemical reaction is intensified by the large-eddy vortex structures. 展开更多
关键词 Swirling combustion . Swirling flows .Large-eddy simulation
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