Changes and Challenges in the '60's

Acoustic radiation from weakly wrinkled premixed flames

“…We next take the Fourier transform of Eq. (8). Since from this point forward we only consider each variable's Fourier transform, we will utilize the same symbol for the time domain and Fourier-transformed variable; i.e., u (r, θ, t) → u (r, θ, ω):…”

“…Theoretical work on the subject appears to have been initiated by an analysis of Bragg [8]. Subsequent studies by Chiu and Summerfeld [9], Strahle [1], Hassan [10], and others developed approximate wave equations describing the sound generation by unsteady heat-release processes.…”