Large-Scale, Explicit Wave Simulations on the CRAY-2
Abstract
Most time-domain, wave problems in geophysics are intractable by classical analysis methods, due principally to non-separability and to a lesser extent material nonlinearity. Therefore discrete numerical solutions are often necessary for the simulation of realistic models. Applications in 2-D and 3-D geophysical modeling are the subject of this paper, particularly as solved on a Cray-2 supercomputer. Implementation and performance differences between earlier CRAYs and the CRAY-2 are described, including the discrepancy between scalar fetch and vector processing speeds. Explicit finite element solvers are applied to applications involving 2-D simulation of a seismic refraction experiment across the state of Maine, 3-D simulation of near-source scattering experiments, and both linear and nonlinear axisymmetric source simulation. Results show that the CRAY-2 allows cost-effective 2-D simulations of truly large-scale models, but only begins to be effective in 3-D for models of interest in geophysics. The large memory (256 megawords) is adequate but a speed increase of at least an order of magnitude is necessary for cost-effective 3-D. True multiprocessor capability (rather than 'multi-computer') provides an alternative to raw speed but involves another set of difficulties. (Reprints).
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 11, 1988
- Accession Number
- ADA201531
Entities
People
- D. K. Vaughan
- G. L. Wojcik
- J. Mould
- M. B. Hulit
- M. Barenberg