Full Waveform Inversion in generalized coordinates for zones of curved topography

Full waveform inversion (FWI) has been recently used to estimate subsurface parameters, such as velocity models. This method, however, has a number of drawbacks when applied to zones with rugged topography due to the forced application of a Cartesian mesh on a curved surface. In this work, we present a simple coordinate transformation that enables the construction of a curved mesh. The proposed transformation is more suitable for rugged surfaces and it allows mapping a physical curved domain into a uniform rectangular grid, where acoustic FWI can be applied in the traditional way by introducing a modified Laplacian. We prove that the proposed approximation can have a wide range of applications, producing precise near-surface velocity models without increasing the computing time of the FWI.

Three-Dimensional Flowfield Prediction

The development, use and application of a three-dimensional fluid flow computer code is described. The code runs on microcomputers with effective 3-D perspective color graphic displays of the results. The present version of the code retains several simplifications, uses a uniform rectangular grid system, and runs on microcomputers, thus providing a powerful and economical software capability. Equations are solved for the fully 3-D problem, including pressure, three velocity components and species mass fractions. The simulation is a finite difference time-marching procedure using an explicit formulation of the conservation equations, followed at each step by an iteration updating pressures and velocities so as to impose the continuity requirement. The present paper documents the problem, describes briefly its simulation, theory and assumptions, and gives results showing an application of the code to co-flowing round jet mixing.