Interactive Control in Turbulent Shear Layers
Final rept. Feb 1990-Jan 1993
ILLINOIS INST OF TECH CHICAGO FLUID DYNAMICS RESEARCH CENTER
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Investigations of wall-bounded shear flow at IIT have been primarily focused on the following issues 1 inner- and outer-layer effects on the dynamics of a turbulent boundary layer TBL, 2 a PIV study of fully developed turbulent pipe flow, 3 the effects of intermittency on the wall-layer dynamics and 4 the visualization of active events near the wall. The motivations behind these investigations are to understand the Reynolds number sensitivity and relative importance of the different scales of motion, with regard to the dynamics of turbulent wall-bounded flow and to document and study the instantaneous structure of the flow vis-a-vis the numerous coherent structure studies of the last two decades. A temporal filtering scheme was devised to separate the contribution of the different scales of motion to the u signal and the Reynolds stress in the buffer and logarithmic region. Also, using PIV, instantaneous large-scale structures were observed, which are not seen in low Reynolds number direct numerical simulations of bounded turbulent shear flows. The analysis of flow visualization records of active events in a TBL was performed in the frame of a conjectured model that is based on Theodorsens original hairpin vortex flow module. Information on the character, size, location, intensity and duration of the events was documented and tabulated.
- Radiofrequency Wave Propagation