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[2012-03-21]
Professor Shiyi Chen talks new methods for turbulent flow simulations
Professor Shiyi Chen, dean of the College of Engineering and director of State Key Laboratory for Turbulence and Complex Systems, gave a talk on turbulent flows simulation titled, "Constrained Large Eddy Simulation for Incompressible and Compressible Separated Turbulent Flows," during the Kavli Institute for Theoretical Physics China (KITPC) program, "New Directions in Turbulence," on March 15.
The program is hosted by KITPC of the Chinese Academy of Sciences, which serves as a platform for experts in turbulence to communicate recent developments with a hope to identify promising breakthrough directions. Eighty-four scientists from theory, numerics and experiments have participated.
Chen introduced the framework of constrained large eddy simulation (CLES). He showed how the basic idea of CLES evolved from the constraints of the decimation method and molecular dynamics. The dynamics subgrid scale stress model for large eddy simulation (LES) with an energy flux constraint improved the prediction of energy spectrum. Chen then exhibited an important application of the CLES method. The hybrid RANS/LES methods are the most promising tools for turbulence simulation; the Detached Eddy Simulation (DES) developed by Boeing Company is now most widely used .
The RANS/LES methods have some faults which cause the mismatching of inner and outer flow fields and may lead to inaccurate predictions of mean flow. Chen and his research group developed a Reynolds stress constrained large eddy simulation (R-CLES) method which eliminated the nonphysical buffer layer produced by RANS/LES methods and obtained more precise results than DES, with the same cost of computation. Chen showed the simulations of incompressible and compressible separated around cylinder, airfoil and periodic hills using CLES method. The CLES method has been planted in the CFD software developed by Peking University and has potential use in aviation aerodynamic design.
Among the attendees were Professor Zhensu She, Professor Busse, Professor Biferale, Professor Procaccia, Professor Birnir and other COE teachers and students.