The graph only looks like it has two plots because the first Euler method fits so well compared to the backwards ordered one. Notice that the backwards ordered Euler gets worse over time.

Euler–Maruyama Method: A numerical scheme for approximating solutions of stochastic differential equations through discrete time stepping.

We show that the increased spatial accuracy of the postprocessing procedure is not affected by the errors arising from any convergent time-stepping procedure. Further refined bounds are obtained when ...

Two parallel, non-iterative, multi-physics, domain decomposition methods are proposed to solve a coupled time-dependent Stokes-Darcy system with the Beavers-Joseph-Saffman-Jones interface condition.