CSAR Seminar

SPEAKER: Hongwu Zhao, University of Colorado at Boulder

TITLE: Hypersonic Boundary-Layer Instability, Anisotropic Turbulence Simulation, and Free Wake Modeling

DATE: Thursday, November 30, 2006
TIME: 9:30 A.M.
PLACE: 2240 DCL
1304 W. Springfield Ave., Urbana, IL

ABSTRACT

In this presentation, I will describe three major research projects I have pursued in recent years. First, I will give an introduction to my Ph.D. dissertation research, in which I studied hypersonic boundary-layer instability and flow transition numerically by linear stability theory and direct numerical simulation. The flow transition mechanism in the presence of shock-wave/boundary-layer interaction has been revealed by this study. The most unstable mode was also found and can be useful in the design of the Hyper-X flight vehicle propulsion system inlet flow tripping device.

Next, I will discuss my postdoctoral research projects at the University of Colorado at Boulder. In my first postdoctoral project, I developed a dynamic Lagrangian Averaged Navier-Stokes (LANS-±) model. This model was then tested in decaying isotropic homogenous turbulence simulation, a-priori tests, and turbulent channel flow simulation. All of these tests indicate that the dynamic LANS-± model is suitable for anisotropic turbulence simulation and it also shows some advantages over the traditional RANS and LES model. My second postdoctoral research project is to perform helicopter rotor flow simulation by free wake modeling. In this research, I combined the free wake modeling technique with full Navier-Stokes simulation to simulate the helicopter rotor flow. By this approach, the influence of the rotor far wake on the near field solution is recovered accurately without increasing the simulation domain and mesh resolution. Very accurate simulation results can be achieved by using only partial simulation domain

Finally, I will give a brief introduction to other projects I have performed, including compressible LANS-± model development, compressible turbulence simulation, microfluidic simulation, and zonal RANS/LES for helicopter rotor flow. My future research plans will also be discussed.