Mesh Sensitivity of Blast Wave Propagation

Calculation of blast propagation in air from a high explosive detonation is an often-used feature of LS-DYNA®’s Eulerian capabilities. To obtain credible results, a suitably fine mesh is needed, particularly in the vicinity of the explosive, to represent the nearly instantaneous rise of shock pressure and its gradual decay. In this paper, we aim to present a set of generally applicable guidelines for mesh refinement, using both 2-D axisymmetric and fully 3-D meshes. Models of a Composition B spherical detonation were exercised using various mesh sizes and for charges of varying mass. Simulations made use of the high explosive burn material model and initial detonation card within LS-DYNA. The results were evaluated based on the total impulse at various scaled standoff distances, and then characterized in terms of a scaled mesh dimension (scaled by the cube root of the charge mass). This relationship can be used in future studies to evaluate the trade-off between computational intensity and accuracy of results.