Amplitude modulation of pressure in turbulent boundary layer

The interaction between pressure fluctuations associated with large- and small-scale motions is studied. Using a small pressure probe, both static pressure and wall pressure fluctuations were measured inside the zero-pressure gradient boundary layer at relatively high Reynolds numbers. How the large scales in the log-region affect the small scales near the wall is analyzed by means of an amplitude modulation procedure. Analyzing the wall pressure fluctuations, it was found that the large scale interacts with the small scale but there is a time-lag between them.