AR = cavity aspect ratio a = speed of sound b = cavity half-width ~ C = dynamic compressibility c = phase speed cp = specific heat at constant pressure f = frequency H = cavity depth k = wave number m = propagation constant P = pressure Pr = Prandtl number R = reflection coefficient p = acoustic pressure pi = initial pulse amplitude Re = acoustic Reynolds number s = cavity spacing T = temperatu...

The pressure reflectance R (omega) is the transfer function which may be defined for a linear one-port network by the ratio of the reflected complex pressure divided by the incident complex pressure. The reflectance is a function that is closely related to the impedance of the 1-port. The energy reflectance R (omega) is defined as magnitude of [R]2. It represents the ratio of reflected to incid...

We propose mathematical models to describe the behaviour of smart obstacles. In the context of acoustic scattering a smart obstacle in an obstacle that when hit b y an incoming acoustic wave reacts circulating on its boundary a “pressure current” to pursue a given goal. A pressure current is a quantity whose physical dimension is pressure divided by time. The goals considered are: 1) to be unde...