Frequency-domain Full-waveform Modeling Using a Hybrid Direct-iterative Solver Based On a Parallel Domain Decomposition Method: a Tool For 3D Full-waveform Inversion?

We present a parallel domain decomposition method for frequency-domain modeling of wave propagation. The domain decomposition method, based on the Schur complement method, uses an hybrid direct-iterative solver. The main interest of mixing solvers is to overcome the huge memory complexity of direct solvers while partially preserving the efficiency of multi-RHS simulations and mitigate the iteration count in iterative solvers. To improve the convergence rate of the iterative solver, a preconditioning provided by the local assembled Schur complement is used. Discretization of the time-harmonic wave equation (Helmholtz equation) is based on a parsimonious staggered finite-difference grid method but the domain decomposition method could apply to any numerical scheme such as finite-element or finite-volume methods. We developed this method as a tool for frequency-domain fullwaveform inversion.