Reference guide to WPP version 2.0

Petersson, A ; Sjogreen, B

关键词: BOUNDARY CONDITIONS;    COMPUTER CODES;    DISTRIBUTION;    RESOLUTION;    SEDIMENTARY BASINS;    SEISMIC WAVES;    SIMULATION;    SOURCE TERMS;    TOPOGRAPHY;    VALIDATION;    WAVE EQUATIONS;   

DOI  :  10.2172/972851
RP-ID  :  LLNL-TR-422928
PID  :  OSTI ID: 972851
Others  :  TRN: US201006%%524

美国|英语

来源: SciTech Connect

【 摘 要 】

WPP is a computer program for simulating seismic wave propagation on parallel machines. WPP solves the governing equations in second order formulation using a node-based finite difference approach. The basic numerical method is described in [9]. WPP implements substantial capabilities for 3-D seismic modeling, with a free surface condition on the top boundary, non-reflecting far-field boundary conditions on the other boundaries, point force and point moment tensor source terms with many predefined time dependencies, fully 3-D heterogeneous material model specification, output of synthetic seismograms in the SAC [4] format, output of GMT [11] scripts for laying out simulation information on a map, and output of 2-D slices of (derived quantites of) the solution field as well as the material model. Version 2.0 of WPP allows the free surface boundary condition to be imposed on a curved topography. For this purpose a curvilinear mesh is used near the free surface, extending into the computational domain down to a user specified level. The elastic wave equations and the free surface boundary conditions are discretized on the curvilinear mesh using the energy conserving technique described in [2]. A curvilinear mesh generator is built into WPP and the curvilinear mesh is automatically generated from the topography. Below the curvilinear grid, the elastic wave equation is discretized on Cartesian meshes, which leads to a more computationally efficient algorithm. In version 2.0 of WPP, Cartesian local mesh refinement can be used to make the computational mesh finer near the free surface, where more resolution often is needed to resolve short wave lenghts in the solution, for example in sedimentary basins. The mesh refinement is performed in the vertical direction and each Cartesian grid is constructed from user specified refinement levels. In this approach, the grid size in all three spatial directions is doubled across each mesh refinement interface, leading to substantial savings in memory and computational effort. The energy conserving mesh refinement coupling method described in [10] is used to handle the hanging nodes along the refinement interface. The examples subdirectory of the WPP source distribution contains several examples and validation tests. Many Matlab/octave scripts are provided in the tools directory.