A new approach to building explicit time-marching stencil computation schemes for the transient two-dimensional acoustic wave equation is implemented. It is based on using Poisson's formula and its three time level modification combined with polynomial stencil interpolation of the solution at each time-step and exact integration. The time-stepping algorithm consists of two explicit stencil computation procedures: a first time-step procedure incorporating the initial conditions and a two-step scheme for the second and next time-steps. Three particular explicit stencil schemes (with 5, 9, and 13 space points) are constructed using this approach. Their stability regions are presented. All of the obtained first time-step computation expressions are different from those used in conventional finite-difference methods. Accuracy advantages of the new schemes in comparison with conventional finite-difference schemes are demonstrated by simulation using an exact benchmark solution. K E Y W O R D S 2D wave equation, first time-step, stencil computation, two-step scheme
INTRODUCTIONStencil computations are widely implemented in many numerical algorithms that involve structured grids. In acoustic field simulation based on two-(2D) or three-dimensional transient wave equations, the finite difference time domain method is a standard approach leading to stencil operations. 1 Finite difference schemes for the 2D wave equation have been extensively employed in seismic simulations and linear modeling of vibrations of membranes. In an explicit time-stepping finite difference scheme, a solution value at each point in a time-space grid is calculated using a linear combination of values at its spatial neighbors from previous time steps. Among such schemes the main attention in the literature has been given to two-step schemes (which operate over three time levels t k+1 = (k + 1) , t k = k and t k−1 = (k − 1) where is a fixed time increment). They have been intensively studied and described in many articles and books (eg, References 2-7). More recent developments on explicit two-step finite difference schemes, particularly on high-order schemes, are reviewed in References 8-11. Some related issues of computational complexity of explicit finite difference schemes are discussed, for example, in References 12,13. Explicit two-step numerical schemes for the scalar wave equation can also be devised based on spherical means representations as it is done in Reference 14 where an integral evolution formula with three time levels is derived. For the This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.