NUMERICAL SIMULATION IN A WAVE TANK FILLED WITH SAND

We develop a pseudospectral modeling algorithm for wave propagation in anelastic media with Dirichlet and Neumman boundary conditions. The method also allows to set non-reflecting boundaries. The modeling can be adapted to laboratory experiments, namely the implementation of free-surface, rigid and non-reflecting boundary conditions at the model boundaries, as for instance, a tank to perform physical modeling. The time-domain equations for propagation in a viscoelastic medium are described by the Zener mechanical model, that gives relaxation and creep functions in agreement with experimental results. The algorithm is based on a two-dimensional Chebyshev differential operator for solving the viscoelastic wave equation. The technique allows the implementation of non-periodic boundary conditions at the four boundaries of the numerical mesh, which requires a special treatment of these conditions based on one-dimensional characteristics. In addition, spatial grid adaptation by appropriate one-dimensional coordinate mappings allows a more accurate modeling of complex media, and reduction of the computational cost by controlling the minimum grid spacing. An example is shown, where we compute microseismograms in a tank filled with lossy sand.