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Show CHAPTER 4 SAMPLE SIMULATIONS Using the parallel distributed algorithm presented in Chapter 3, a number of models were selected to verify the robustness and stability of its implementation. The examples in this chapter aim to show that the parallel distributed program implemented in this work is capable of handling arbitrary models including a multilayered model, acoustic-elastic boundaries, as well as complex structures with lateral velocity variations. 4.1 Snapshots from a Homogeneous Jlalfspace The first simulation involves a simple homogeneous halfspace with P-wave velocity of 3000 mjs, S-wave velocity of 1730 m/s, and a density of 2500 Kg/m3 • The corresponding Poisson's ratio is 0.25. The model used was a 3D cube of 100x100x100 grid points, with a grid spacing of 5 meter and a simulation time step of 0.0007 seconds. The stability criterion used was 0.420 (Vmax~t/h) for this and the following simulations. Snapshots of the vertical component of displacement were taken every 50 time steps (35 ms) for 350 ms at the three central planes of the model parallel to each of the three coordinates. The source used was an explosive point source with a dominant frequency of 30 Hz placed at the center of the model, i.e., the point (50,50,50). The resulting frames recorded at the planes parallel to the X, Y, and Z coordinates are shown in Figures 4.1, 4.2, and 4.3, respectively. |
