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detached-eddy simulation of turbulent coherent structures around groynes in a trapezoidal open channel

Journal of Hydrodynamics 2020年第2期32卷 326-336页

作者： Jing-xin Zhang Jian Wang Xiang Fan Dongfang Liang Key Laboratory of Hydrodynamics(Ministry of Education) shanghai Jiao Tong UniversityShanghai200240China School of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China

The hydrodynamics in a straight open channel with a multiple-embayment groyne field was investigated using the detached-eddy simulation(DES).A series of short groynes were included on a 1:3 side slope of the channel.This work focuses on the turbulent coherent structures around groynes on an uneven bottom.Flows around groyne fields are characterized by massive separation and highly unsteady vortices.DES can capture a wide spectrum of eddies at a lower computational cost than the large eddy simulation(LES)or direct numerical simulation(DNS).In the present work,a zonal DES model(ZDES)was used to simulate the flow around groynes.The ZDES model is a modified version of the DES designed to overcome the model-stress depletion(MSD)of the RANS/LES hybrid model.The vortex system consists of the horseshoe vortex(HV)formed at the base of the obstructions,the necklace vortex(NV)that wrapped the groyne tips near the free surface,and the shedding vortex(SV)underneath the free surface.The effects of the incident flow and local topography on the vortex evolution were investigated by analyzing the mean flow structures and the instantaneous turbulent flow fields.Some important vortices cannot be captured because of the averaging process,while some flow structures cannot be observed in the instantaneous flow.The mean flow is only a reflection of the averaging process when complex vortices are present.

关键词： Open channel flow groyne free surface detached eddy simulation turbulent coherent structure

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Numerical simulation and a hybrid method of supersonic turbulent base heating

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航空动力学报 2018年第10期33卷 2442-2450页

作者： YUAN Junya CAI Guobiao ZHAO Lu School of Astronautics Beijing University of Aeronautics and Astronautics Beiiing 100191 China

detached eddy simulation(DES)model was used to better capture large vortex structure and unsteady flow feature near cone base.Good base heating results were achieved using proper grid and numerical method.The influence of inflow conditions(like Mach number,Reynolds number)and configuration(bluntness ratio of the cone)on base heating was discussed based on numerical computational results.Compared with base heat flux,base pressure can be predicted more accurately by numerical simulation and the time consuming was shorter.A hybrid method combining numerical simulation with experimental correlation was proposed to predict supersonic turbulent base heating.A review of base heating experiment and correlations for slender cone was presented,and a revised correlation was proposed based on the above simulation results.Compared with the experiment data,the maximum error was 24%,agood result for base heating prediction.This proves that the hybrid method using the revised correlation performs well in predicting supersonic turbulent base heating of slender sphere cone and can meet needs of engineering design.

关键词： base heating detached eddy simulation hybrid method experimental correlation slender sphere cone

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DEVELOPMENT OF HYBRID RANS / LES CODE AND ITS VALIDATION

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Transactions of Nanjing University of Aeronautics and Astronautics 2013年第1期30卷 24-32页

作者：吴晶峰宁方飞 School of Jet Propulsion Beijing University of Aeronautics and Astronautics

A computational code based on the hybrid RANS-LES approach is developed.The hybrid approach combines the delayed detached-eddy simulation ( DDES ) with an improved RANS-LES hybrid model aiming at wall modeling in LES ( WMLES ) .In the code , the convective flux is solved using the fourth-order skew-symmetric scheme so as to diminish the negative effect of numerical dissipation.The Spalart-Allmaras ( S-A ) model is applied as a subgrid scale ( SGS ) model.To validate the developed code , homogeneous isotropic turbulence and turbulent channel flow are simulated and the results are compared with experimental data and DNS results.The results of the isotropic turbulence show that the fourth-order skew-symmetric scheme is adequate enough and the model works well coupling with the convective scheme.The results of the turbulent channel flow agree well with the DNS data , the predicted velocity profiles at Reynolds number from 178to 2 700match well with the Reichardt′s law , and the organized vortical structures are well captured.

关键词： turbulent channel flow detached eddy simulation convection scheme

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