In this work, we have formulated a class of asymptotic-preserving (AP) semi-Lagrangian (SL) discontinuous Galerkin (DG) methods, designed for kinetic transport equations under a diffusive scaling. They are built upon a characteristics-based model reformulation, which comprises a convection-diffusion-like equation for the macroscopic density and another evolution equation for the distribution function. We employ the equations in a weak form to enjoy the advantages of a DG method. We also leverage a semi-Lagrangian (SL) approach to achieve higher efficiency than a fully implicit scheme, without loss of unconditional stability. A damping technique is introduced to control spurious numerical oscillations for high-order DG methods. We establish formal AP and Fourier stability analyses for fully discrete schemes in a linear scenario. Numerical experiments, covering 1D to 3D in space problems, confirm the accuracy, AP property, uniformly unconditional stability, and high parallel efficiency of the proposed methods.

This is a joint work with Yi Cai, Guoliang Zhang and Hongqiang Zhu.