An Asymptotic-Preserving IMEX Method for Nonlinear Radiative Transfer Equation

We present an asymptotic preserving method for the radiative transfer equations in framework of $$P_N$$ method. An implicit and explicit numerical scheme is proposed to solve system based on order analysis expansion coefficients specific intensity, where each coefficient derived by Chapman-Enskog The at higher-order are treated explicitly while those lower-order implicitly equation system. Energy inequality proved this scheme. Several examples validate efficiency both optically thick thin regions.