Time domain filter application in wave propagation problems.

Resumo

Often in wave propagation problems with explicit methods, instabilities at high frequencies appears.
In methods with structured meshes, spatial filters can be used, but with unstructured meshes the construction of
such filters is more complex. In this work, the high frequencies resulting from instability due to numerical errors
are smoothed with the use of filters in the time domain, making a convolution at each time step. Butterworth IIR
(infinite impulse response) digital filters of maximum flatness are used.