Absorption of Sound by Sound at Degenerative Interaction of Acoustical Waves

O.A.Savitsky (Department of Mathematics, Taganrog State University of Radio Engineering, Taganrog, Russia); A.M.Gavrilov (Department of Electro Hydroacoustics and Medical Engineering, Taganrog State University of Radio Engineering, Taganrog, Russia)

e-mail: caviton@tgn.ru

The comparative analysis of a sound by sound absorption (SSA) is given at different frequency relations between a signal and pump waves. It is shown, what the extreme display of SSA effect has a place at a pump wave frequency fp twice greater than a signal frequency fs, which corresponds to degenerate three-wave interaction. The "resonant" character of frequency and phase dependence of SSA in a degenerate case is marked. It is offered to distinguish SSA at fp/fs=2 and interference signal wave suppression at fp/fs=0.5, which is caused by process antiphase generation on a signal frequency. The monotonic character of spatial decrease of signal wave amplitude is characteristic for a case SSA.  The quantitative assessment SSA, and its comparison with a nonlinear self-absorption is given.  The results of experimental examinations confirming regularities of SSA obtained from Burgers equation are given. Is shown, that in a beam the signal absorption in a near-field zone has oscillating, and in a far-field - monotonic character. Simultaneously there is a change of an interference pattern of a field and isotropization of an angular distribution of signal wave amplitude. The problems of practical use SSA are considered.


Section : 4