This is the Final Research Report on a project whose major goals were to incorporate experimental and numerical simulations to capture blood fluid atomization, bloodstain patterns, and in-flight droplet behavior.
Experimental methods included high-speed and laser-based holographic imaging to provide three-dimensional information about the trajectories and mechanisms of blood droplets and blood atomization processes relevant to forensic analysis of bloodstain patterns. A series of studies proceeded relevant blood-letting events that ranged from blunt impact to high-velocity bullet impact. Experimental results are available for continued use by both the forensics and fluid dynamics communities for test and comparison models. The major achievements of this project have included contributions to the fluid mechanics and forensic pattern analysis associated with bloodstain patterns. The theoretical modeling developments have contributed to dealing with arbitrary bullet shapes, predicted the distribution of backspatter droplets, and examined the influence of muzzle gases from a self-similar vortex theory. These contributions have significantly advanced the fluid mechanics associated with backspatter events with consideration of the formation of droplets, their propagation, and the potential for interaction with oncoming muzzle bases. Coupled with experimental observations, these advances will enable further refinement of fluid mechanic models. The project has also resulted in datasets of blood droplet size and velocities in situ, using high-speed imaging and holography techniques. Comparison of such results with resulting bloodstain patterns will permit analysis of drag-based models and enable assessment of other potential uncertainties in the analysis of bloodstain patterns.