“…Note that, in the absence of initial conditions, only time approximations are required, as the boundary consists only of the two nodes at x = 0 and at x = L. The second formulation, named D-BEM, where D means domain, employs a static, or steady-state, fundamental solution instead of a time-dependent one, e.g. [5,12,21]. As a consequence, a domain integral containing the second-order time derivative of the potential, or the acceleration, appears in the BEM basic integral equation: this domain integral is responsible for the designation D-BEM, as the solution of the problem requires the discretization of the entire domain, diversely from the TD-BEM formulation, where the domain discretization is required only when non-homogeneous initial conditions appear.…”