One difficulty in developing numerical methods for tsunami modeling is the
fact that solutions contain regions where much higher resolution is required
than elsewhere in the domain, particularly since the solution may contain
discontinuities or other localized features. The Clawpack software deals with
this issue by using block-structured adaptive mesh refinement to selectively
refine around propagating waves. For problems where only a target area of the
total solution is of interest (e.g. one coastal community), a method that
allows identifying and refining the grid only in regions that influence this
target area would significantly reduce the computational cost of finding a
solution.
In this work, we show that solving the time-dependent adjoint equation and
using a suitable inner product with the forward solution allows more precise
refinement of the relevant waves. We present examples solving the shallow water
equations in one and two dimensions. To perform these simulations, the use of
the adjoint method has been integrated into the adaptive mesh refinement
strategy of the open source GeoClaw software. We also present results that show
that the accuracy of the solution is maintained and the computational time
required is significantly reduced through the integration of the adjoint method
into adaptive mesh refinement.Comment: Much of this material appeared in a previous pre-print, which can be
found at arXiv:1511.03645 . Here, the material has been rewritten to focus on
shallow water equations and submitted to a more application focused journa