HIGH-PRECISION ARTIFICIAL BOUNDARY CONDITION FOR SCALAR WAVE PROPAGATION IN VERTICAL STRATIFIED MEDIA

To realize the efficient and high precision solution of the scalar wave propagation problem in the field with vertical stratified media and irregular surface topography, a high-precision artificial boundary condition is established based on continuous fraction expansion and the extension of consistent boundary. The proposed artificial boundary condition can be applied to sites with zigzag surfaces by introducing an independent oblique coordinate transformation in each vertical layer. The frequency-domain artificial boundary condition only has the continuous fraction order as an undetermined parameter, which can be used to adjust the calculation accuracy and is independent of frequency and incidence angle of outgoing propagating waves. The artificial boundary conditions can be seamlessly coupled with finite element methods for the inner finite domain, which is easy to use. Due to the high precision of the boundary condition, the size of the finite domain can be very small, or even directly added to the ground surface or around the structure, thus greatly improving the computational efficiency. The validity and accuracy of the artificial boundary condition are verified by comparing with the finite element model in typical numerical examples.