ACOUSTICAL FINITE-DIFFERENCE TIME-DOMAIN SIMULATIONS OF SUBWAVELENGTHGEOMETRIES

Accurate simulation of wave propagation around subwavelength geometrie s using standard finite-difference time-domain (FDTD) techniques requi re a fine spatial and temporal sampling resulting in high computationa l costs. In this paper an extension to this standard FDTD technique is proposed by means of quasi-stationary solutions on a subwavelength sc ale. The FDTD equations in the region near the subwavelength geometry are extended with some correction terms of which the magnitude is extr acted from the quasi-stationary pressure distribution around these geo metries. These pressure distributions can be calculated from the Lapla ce equation. Using this new technique, FDTD simulations can be based o n a more coarse grid, thus reducing computational cost considerably. T he accuracy of this technique is mainly determined by the accuracy of the Laplace solutions. This technique was tested with success on the s imulation of resonators. It was also shown that the new FDTD equations can be extended to include viscosity effects. (C) 1998 Acoustical Soc iety of America. [S0001-4966(98)06908-2].