Simulation of compressible turbulent flows

Air Force Office of Scientific Research           Graduate Student: Yucheng Hou 
Hypersonics Center

 

                  

Our work on compressible turbulence is motivated by two problems - acoustic instabilities in gas -turbine combustors and shock wave / boundary layer interaction in high-speed flows. Acoustic instabilities are challenging to simulate because they result from pressure fluctuations in reacting flows at very low Mach number. Large differences between convective time-scales and the speed of sound (i.e. low Mach number) result in numerically stiff systems. We have developed a novel computational algorithm (publication 1 below), which handles this stiffness by solving a rescaled form of the governing equations so that the fast acoustic modes are naturally projected out at low Mach numbers. Also, the algorithm is non-dissipative, and recovers the incompressible equations in the low Mach number limit. It is discretely energy-conserving in the incompressible limit, which makes it very robust without numerical dissipation at high Reynolds numbers in the absence of shock waves.

Publications

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