“…To construct bound-preserving schemes for equation (1.1), we can first consider bound-preserving schemes for a convection-diffusion equation, e.g., F (φ) ≡ 0. In the literature, there are many fully explicit high order accurate bound-preserving schemes for a scalar convection-diffusion equation [3,7,9,17,19,20,22]. In these schemes, the time discretizations are high order explicit time strong stability preserving (SSP) Runge-Kutta and multistep methods, which are convex combinations of forward Euler steps.…”