FDTD算法的线性预测吸收边界条件

Linear Prediction Absorbing Boundary Condition of Finite-difference Time-domain Method

提出了一种全新的FDTD吸收边界条件———线性预测吸收边界条件 (LinearPredictionAbsorbingBoundaryCondition———LPABC)。通过对吸收边界上的入射场进行深入的分析研究 ,发现在某些条件下吸收边界上的场值与入射方向上其相邻区域的场值是线性相关的 ,从而提出了一种利用入射方向相邻区域的场值对吸收边界上的场值进行线性预测的吸收边界条件。采用这种吸收边界条件 ,计算域内的场为行波场 ,在边界处是无反射的。此外 ,这种吸收边界条件不需要设置额外的吸收层 ,也不需要存储前一时刻的场值。最后进行了FDTD实际计算 。

Linear prediction absorbing boundary condition(LPABC) is developed in this paper. The property of linear dependence can be found out in some cases between the field on the boundary and the field in the incidence space when analyzing the incidence field. Based on the linear dependence property, LPABC is developed which use the field in the incidence space to linearly predict the field on the absorbing boundary. With LPABC, the wave in the calculating space is traveling wave, and there are no reflections on the boundary. Additional absorbing layer is not needed with LPABC, and the storage of previous time field is also not needed. The result of numerical calculation also demonstrates that LPABC is effective.