Propagation of nonlinear acoustic waves and beams

• In the project basic problems of nonlinear acoustic wave propagation are studied. The aim of the project is to generalize the results to more complicated problems, such as propagation of nonlinear sound beams and nonlinear wave propagation in dispersive or layered media. Applications are found to propagation of shocks and signals in the sea and in the atmosphere. Examples of problems studied by use of equations of Burgers' type are: finding asymptotic waveforms originating from spherical and cylindrical sine waves, short pulses and stochastic pulses, finding information on original waves from nonlinearly deformed waves and design of effective shock pulses in sound beams. 
  Researchers: B.Enflo, S.Gurbatov (Nizhny Novgorod), C.Hedberg (Karlskrona)
  Source of funding:  TFR 

 

Diffraction of sound by noise barriers

• Noise from traffic, fans, motors etc. is often shielded by barriers. In normal design the top edge of a noise barrier is straight. The edge may act as a string of highly correlated point sources. The effectiveness of the barrier is reduced by the coherence of these secondary sources. Experiments at The University of Texas show that the effectiveness of the barrier can be increased if it is made irregular. The project aims at understanding of these phenomena by theoretical methods. It will continue with theoretical and experimental investigations of possibilities of increasing the efffect of sound barriers. 
  Researchers: B.Enflo, I.Pavlov
  Source of funding BFR, KFB