DGTD Introduced Incident Plane Wave And 2D DGTD/FDTD Hybrid Algorithm

As a new time domain algorithm,the Discontinuous Galerkin Time Domain(DGTD)method,has been widely used in the calculation of Radar Cross Sections(RCS).When calculating the scattering properties of the target,the introduced plane waves into the computational domain plays a crucial role.At present,there are analytical method and 1D Incident Field Array(IFA)method for introducing incident plane waves in DGTD domain.Due to the algorithm mismatch between the 1D-FDTD method and DGTD algorithm,the leakage into scattered field is large.In order to make up for the error caused by the mismatch,this paper proposes a 1D-DGTD method for introducing incident plane waves,in which 1D-DGTD uses a one-dimensional linear basis function to discretize in space,and uses Leap-frog(LF)to discretize in time.The upwind flux is used as the information flow between units.Compared to the 1D-FDTD method,the numerical results show that the 1D-DGTD method has less leakage.Aiming at the two-dimensional DGTD and FDTD hybrid algorithms,this paper proposes a boundary coupling technique based on virtual elements,so that the two algorithms can be well coupled.At the same time,in order to reduce the reflected wave of the coupling boundary and improve the calculation accuracy,the DGTD grid adopts a specific subdivision method.Two-dimensional DGTD/FDTD numerical examples verify the correctness of the method.Specific research work includes:1.Research on incident plane wave of DGTD algorithm.The DGTD updated iterative formula of the 2D TM-wave and the calculation of the cell matrix and surface flux matrix in the formula are derived in detail.On this basis,the total field/scattered field(TF/SF)technique and the specific realization method of two-dimensional DGTD introduced incident plane waves are given.Aiming at the problem of large leakage caused by the traditional method of introducing incident waves,the 1D-DGTD method is proposed to be improved.Compared with the traditional method,the correctness of the method is verified in the two-dimensional DGTD numerical example of TM wave.2.Research on DGTD/FDTD hybrid algorithm.For the hybrid algorithm of DGTD and FDTD,a boundary coupling technique based on virtual element is proposed.Taking the two-dimensional TM wave as an example,the implementation of this technique is discussed in detail,and the iterative steps of DGTD/FDTD are given.Besides,a specific meshing method is used to reduce the reflected waves generated when the algorithm is coupled.A two-dimensional numerical example shows the correctness of the method.