A theoretical model for predicting and interpreting blood-spatter patterns resulting from a gunshot wound is proposed. The physical process generating a backward spatter of blood is linked to the Rayleigh-Taylor instability of blood accelerated toward the surrounding air, allowing the determination of the initial distribution of drop sizes and velocities. Then the motion of many drops in air is considered with governing equations accounting for gravity and air drag. Based on these equations, a numerical solution is obtained. It predicts the atomization process, the trajectories of the back-spatter drops of blood from the wound to the ground, the impact angle, and the impact Weber number on the ground, as well as the distribution and location of bloodstains and their shape and sizes. A parametric study is undertaken to predict patterns of backward blood spatter under realistic conditions corresponding to the experiments conducted in the present work. The results of the model are compared to the experimental data on back spatter generated by a gunshot impacting a blood-impregnated sponge.
Bibliographical noteFunding Information:
Support of this work by the US National Institute of Justice (Grant No. NIJ 2014-DN-BX-K036) is greatly appreciated. The authors gratefully acknowledge the skillful shooting of Christopher O’Brian for the acquisition of the experimental data, and Craig Moore who provided sponge targets.
© 2016 American Physical Society.
ASJC Scopus subject areas
- Computational Mechanics
- Modelling and Simulation
- Fluid Flow and Transfer Processes