Unconditional optimal first-order error estimates of a full pressure segregation scheme for the magnetohydrodynamics equations

In this article, a first-order linear fully discrete pressure segregation scheme is studied for the time-dependent incompressible magnetohydrodynamics (MHD) equations in three-dimensional bounded domain. Based on an incremental pressure projection method, this scheme allows us to decouple the MHD system into two sub-problems at each time step, one is the velocity-magnetic field system, the other is the pressure system. Firstly, a coupled linear elliptic system is solved for the velocity and the magnetic field. Next, a Poisson-Neumann problem is treated for the pressure. We analyze the temporal error and the spatial error, respectively, and derive the temporal-spatial error estimates of (Formula presented.) for the velocity and the magnetic field in the discrete space (Formula presented.) and for the pressure in the discrete space (Formula presented.) without imposing constraints on the mesh width (Formula presented.) and the time step size (Formula presented.). Finally, some numerical results are presented to confirm the theoretical predictions and demonstrate the efficiency of the method.