LISA simulations of time reversed ultrasonic experiments

Time Reversed Acoustics (TRA) is a new research field that has generated considerable excitement over the past few years, both as an area of basic science and for its potential applications in several fields [I]. Experiments investigating TRA have been conducted in water, human tissues, flawed materials and in the ocean and are currently being performed on earth materials at the Los Alamos National Laboratory. To complement this experimental work, numerical simulations of Time Reversed Acoustic (TRA) and Elastic (TRE) wave propagation are also performed in the framework of the Local Interaction Simulation Approach (LISA) [2]. These simulations can be useful to investigate the extension of TRA to elastic media and the optimization of the focusing procedures in waveguides and heterogeneous media, both in cavities and TR with mirrors. They can also be used to investigate the application of the method called DORT (Decomposition de l'Operateur de Retournement Temporel)[3] in elastic heterogeneous media. DORT allows one to decompose recorded waveforms and to focus into those that are caused not only by the strongest scatterers, but also by relatively weaker ones.