“…Recently, a two-level strategy has been studied for steady semi-linear elliptic equations and nonlinear PDEs by Xu [33,34], and two-level strategy or multi-level strategy has been studied for the steady Navier-Stokes equations by Layton [21], Layton and Tobiska [26], Layton and Lenferink [23,24] and Layton, Lee and Peterson [25] and Girault and Lions [4] and He et al [11,14,15] and Liu and Hou [27], and two level discretization of flows of electrically conducting, incompressible fluids has been provided by Ervin, Layton and Maubach in [3]. Moreover, a combination of two-level methods and iterative methods for solving the 2D/3D steady Navier-Stokes equations is provided by He et al [17,18].…”