FORMULATION AND VALIDATION OF BERENGERS PML ABSORBING BOUNDARY FOR THE FDTD SIMULATION OF ACOUSTIC SCATTERING

Berenger's perfectly matched layer (PML) absorbing boundary condition for electromagnetic (EM) waves is derived to absorb 2-D and 3-D acoust ic waves in finite difference time domain (FDTD) simulation of acousti c wave propagation and scattering, A PML medium suitable for acoustic waves is constructed, Plane wave propagation in the PML medium is solv ed for both 2-D and 3-D cases and explicit FDTD boundary conditions ar e derived, The equations show that a matched PML medium is a perfect s imulation of free space in that a plane wave does not change its direc tion of propagation or its speed when it propagates from free space in to a matched PML medium, FDTD simulation of a pulsed point source prop agating in two dimensions is carried out to test the performance of th e PML boundary for acoustic waves. Results show that an eight layer PM L boundary condition reduces the reflected error 40 dB over Mur's seco nd order boundary condition.