Modeling the Space-Time Correlations in the Wake Region of a Turbulent Boundary Layer

An empirical turbulence model has been developed for boundary layer flows. The goal is to simulate the statistical behavior of turbulent velocity fluctuations in both space and time using the two-point correlation field. The new model is based on physical concepts from earlier measurements and flow visualizations. In particular, it is useful to think of packets of turbulent fluid that are angled to towards the wall and convect with a velocity similar to the local mean. However, the actual behaviors which exist are complicated and sometimes quite subtle (but physically important). For instance, measurements show that the correlation field is only strongly peaked at zero time delay. This is interpreted in wavenumber space as a rapid decorrelation of the small scale eddies, and is modeled in a way that captures the transition. The new turbulence model has been calibrated using recent measurements and is now available for general studies. Efforts are underway to refine the model, improve its theoretical basis, and confirm its application to high Reynolds number flows.