A Fast Sweeping Model for Calculation of HE Detonation

The programmed burn class of methods pre-calculates the arrival times of detonation waves in high explosives given user-specified geometry and light points. While much less expensive than reactive burn, the assumption of a homogeneous, near ideal CJ detonation velocity is not valid, especially in complicated geometries where local detonation failure will not be modeled accurately. DSD's reliance on detonation shock curvature helps to alleviate this, but it is costly and complicated as it necessitates the solution of parabolic equations. In this work we describe the implementation of a Fast Sweeping Detonation (FSD) programmed burn algorithm in the hydrocode Pagosa via the FSD++ library. This model avoids the bulk of complications and expense of DSD by first computing the normal detonation velocity field Dn(x) using the size-effect curve and edge lag from DSD, and then calculating the arrival time field using the fast sweeping method for the numerical solution of hyperbolic Eikonal equations. Dn(x) need not be a constant nominal Chapman-Jouguet value and may be used during a hydrodynamic simulation by an EOS, such as a velocity adjusted JWL or newly developed DASHER, to account for energy deposition in complicated geometries. This work shows how FSD provides greater than 1000x speedups over traditional, Lund programmed burn models. The verification of this model is demonstrated through problems with analytic solutions, while validation is shown by comparison of the model with experimental data.