Hanging variables in finite element time domain method with hexahedral edge elements

Treatment of hanging variables for nested rectangular and hexahedral elements is formulated. The Galerkin-type treatment that involves the construction of intergrid boundary operator leads to symmetric mass and stiffness matrices, /spl otimes/-method is used for the temporal discretization in the finite element time domain method. The conditions for numerical stability of both implicit and explicit FETD method with hanging variables is obtained via analysis of the spectral properties of the resulting finite element matrices. Numerical examples confirm the stability of the proposed treatment hanging variables.