3-Dimensional Parallel Simulations of Streamer Discharges in Air Considering Photoionization

We perform the 3-D parallel simulations of the streamer discharges in air using the minimal fluid model considering the photoionization. The SP 3 photoionization model, which consists of a series of elliptic equations with coupled boundary conditions, is solved using an alternating iteration method, which separates the coupled elliptic equations into independent equations; during each alternating iteration, a geometric multigrid-preconditioned flexible generalized minimal residual method (FGMRES) solver is used to efficiently solve the elliptic equation in the photoionization model. It is numerically shown that the proposed photoionization solver typically converges to a relative residual of 10 −6 with two to four alternating iterations and has a very good parallel efficiency. The interaction of two double-headed streamers is studied considering the photoionization, using 1000 CPU cores and more than 2 billion mesh cells.