A new iterative solver for the time-harmonic wave equation

The time-harmonic wave equation, also known as the Helmholtz equation, is obtained if the constant-density acoustic wave equation is transformed from the time domain to the frequency domain. Its discretization results in a large, sparse, linear system of equations. In two dimensions, this system can be solved efficiently by a direct method. In...

Closing the performance gap between an iterative frequency-domain solver and an explicit time-domain scheme for 3D migration on parallel architectures

Three-dimensional reverse-time migration with the constant-density acoustic wave equation requires an efficient numerical scheme for the computation of wavefields. An explicit finite-difference scheme in the time domain is a common choice. However, it requires a significant amount of disk space for the imaging condition. The frequency-domain...

Improving multigrid for 3-D electro-magnetic diffusion on stretched grids

We evaluated multigrid techniques for 3D diffusive electromagnetism. The Maxwell equations and Ohm's law were discretised on stretched grids, with stretching in all coordinate directions. We compared standard multigrid to alternative multigrid approaches with linewise smoothing and semi-coarsening, both as a stand-alone solver and as a...

Improving multigrid for 3-D electro-magnetic diffusion on stretched grids

We evaluated multigrid techniques for 3D diffusive electromagnetism. The Maxwell equations and Ohm's law were discretised on stretched grids, with stretching in all coordinate directions. We compared standard multigrid to alternative multigrid approaches with linewise smoothing and semi-coarsening, both as a stand-alone solver and as a...