Dynamics of Waves in Hydrogels

ORAL

Abstract

Dynamics of compression/rarefaction in hydrogels is an emerging new field of fluid mechanics. In the present work it is treated in the framework of forensic research. Formation of the blood and brain tissue backspatter after penetrating gunshots to the head is preceded and driven by formation and evolution of the bullet channel and filling it with muzzle gases and/or the surrounding air. This process is accompanied by formation and propagation of compression/rarefaction waves in such a hydrogel as brain tissue is. In the present work the dynamics of waves is explored using novel rheological constitutive equation of brain tissue. The equations of motion supplemented by this constitutive equation reveal the dynamics of the compression and rarefaction waves propagating through brain tissue following the formation of bullet channel filled with muzzle gases resulting from a short-range shooting. The predicted wave propagation and reflection from a skull and the bullet channel surface proceeds in concert with gas inflow and outflow from the bullet channel, as well as by fragmentation of brain tissue, with the debris issued into the channel, entrained by the outflowing gas, and formation of backspatter toward a gun bore.

–

Publication: P. M. Comiskey, A. L. Yarin, S. Kim, D. Attinger. Prediction of blood backspatter from a gunshot in bloodstain pattern analysis. Physical Rev. Fluids v. 1, 043201 (2016).

A. Kolbasov, P.M. Comiskey, R. P. Sahu, S. Sinha-Ray, A. L. Yarin, B. S. Sikarwar, S. Kim, T.Z. Jubery, D. Attinger. Blood rheology in shear and uniaxial elongation. Rheologica Acta v. 55, 901-908 (2016).

P.M. Comiskey, A.L. Yarin, D. Attinger. High-speed video analysis of forward and backward spattered blood droplets. Forensic Science International, 276, 134-141 (2017).

P.M. Comiskey, A.L. Yarin, D. Attinger. Hydrodynamics of back spatter by blunt bullet gunshot with a link to bloodstain pattern analysis. Phys. Rev. Fluids 073906 (2017).

P.M. Comiskey, A.L. Yarin. Friction coefficient of an intact free liquid jet moving in air. Experiments in Fluids 59:65 (2018).

P.M. Comiskey, A.L. Yarin, D. Attinger. Theoretical and experimental investigation of forward spatter of blood from a gunshot. Physical Review Fluids 3, 063901 (2018).

D. Attinger, Y. Liu, R. Faflak, Y. Rao, B.A. Struttman, K. De Brabanter. P.M. Comiskey, A.L. Yarin. A data set of bloodstain patterns for teaching and research in bloodstain pattern analysis: gunshot backspatters. Data inBrief 22, 269–278 (2019).

D. Attinger, K. P.M. Comiskey, A.L. Yarin, K. de Brabanter. Determining the region of origin of blood spatters using probabilities and fluid dynamics. Forensic Science International 298, 323-331 (2019).

P.M. Comiskey, D. Attinger, A.L. Yarin. Implications of two backward blood spatter models based on fluid dynamics for bloodstain pattern analysis. Forensic Science International, 301, 299–305 (2019).

P.M. Comiskey, A.L. Yarin, D. Attinger. Hydrodynamics of forward blood spattering caused by a bullet of general shape. Phys. Fluids 31, 084103 (2019).

P.M. Comiskey, A.L. Yarin. Self-similar turbulent vortex rings: Interaction of propellant gases with blood backspatter and the transport of gunshot residue. J. Fluid Mech. 876, 859-880 (2019).

G. Li, N. Sliefert, J.B. Michael, A.L. Yarin. Blood backspatter interaction with propellant gases. Phys. Fluids 33, 043318 (2021).

N.Sliefert, G. Li, J.B. Michael, A.L. Yarin. Experimental and numerical study of blood backspatter interaction with firearm propellant gases. Phys. Fluids 33, 043319 (2021).

K. Chen, J. Michael, A.L. Yarin. Effect of secondary atomization on blood backspatter affected by muzzle gases. Phys. Fluids 35, 044115 (2023).

Presenters

  • Valentina Kosmerl

    University of Illinois at Chicago

Authors

  • Valentina Kosmerl

    University of Illinois at Chicago

  • Alexander L Yarin

    University of Illinois Chicago, University of Illinois at Chicago