WAVE-NUMBER MISMATCH OF INTERACTING MODES IN A PLANE WAKE

A technique is presented to examine the level of wavenumber mismatch b etween nonlinearly interacting components whose frequencies obey reson ant matching conditions. Cross-correlation of the auto-bispectrum is u sed to quantify the level of mismatch, and the concept of bispectrum c oherency is introduced to determine the confidence level in the wavenu mber mismatch measurements. The results show that wavenumber mismatch of the order of one tenth of the fundamental wavenumber can exist betw een interacting triads whose frequencies obey resonance matching.