基于改进型绕射非局部边界条件的三维抛物方程分解模型预测电波传播

Combination of the Improved Diffraction Nonlocal Boundary Condition and Three-dimensional Parabolic Equation Decomposed Model for Predicting Radiowave Propagation

绕射非局部边界条件是基于有限差分法求解抛物方程时使用的一种透明边界条件。它的最大优点是只用一层网格就能很好完成波地吸收,而缺点是由于涉及到卷积积分的计算,因此计算速度低。针对此问题,该文首先引入可以加快其计算速度的递归卷积法和矢量拟合法。这里把结合了这两种数值计算方法的绕射非局部边界条件称为改进型绕射非局部边界条件。在此基础之上,提出将这种改进型的绕射非局部边界条件应用到3维抛物方程(3DPE)分解模型中。最后通过数值计算,证明了改性型绕射非局部边界条件3DPE分解模型在计算精度和计算速度方面的优势。

Diffraction nonlocal boundary condition is one kind of the transparent boundary condition which is used in the Finite Difference （FD） Parabolic Equation （PE）. The biggest advantage of the diffraction nonlocal boundary condition is that it can absorb the wave completely by using of one layer of grid. However, the computation speed is low because of the time consuming spatial convolution integrals. To solve this problem, the recursive convolution and vector fitting method are introduced to accelerate the computational speed. The diffraction nonlocal boundary combined with these two kinds of methods is called as improved diffraction nonlocal boundary condition. Based on the improved nonlocal boundary condition, it is applied to Three-Dimensional Parabolic Equation （3DPE） decomposed model. Numeric computation results demonstrate the computational accuracy and the speed of this three-dimensional parabolic equation decomposed model combined with the improved diffraction nonlocal boundary condition.