A Multisolver Scheme Based on Robin Transmission Conditions for Electromagnetic Modeling of Highly Complex Objects

A multisolver scheme based on Robin transmission conditions (RTCs) is proposed for electromagnetic modeling of highly complex objects. Different from the traditional finite element-boundary integral (FE-BI) method that applies BI equations to truncate the FE domain, the proposed multisolver scheme employs both FE and BI equations to model an object along with its background. To be specific, the entire computational domain consisting of the object and its background is first decomposed into multiple nonoverlapping subdomains with each modeled by either an FE or BI equation. The equations in the subdomains are then coupled into a multisolver system by enforcing the RTC at the subdomain interfaces. Finally, the combined system is solved iteratively with the application of an extended preconditioner based on an absorbing boundary condition and the multilevel fast multipole algorithm. To obtain an accurate solution, both the Rao-Wilton-Glisson and the Buffa-Christiansen functions are employed as the testing functions to discretize the BI equations. This scheme is applied to a variety of benchmark problems and the scattering from an aircraft with a launched missile to demonstrate its accuracy, versatility, and capability. The proposed scheme is compared with the multisolver scheme based on combined field integral equations to illustrate the differences between the two schemes.