Forensics Puzzle Cracked via Fluid Mechanical Principles

 

Olivia Gunther

Forensics

Current Event 6

10/30/21

 

“F"Forensics Puzzle Cracked via Fluid Mechanical Principles.” ScienceDaily, ScienceDaily, 20 Apr. 2021, https://www.sciencedaily.com/releases/2021/04/210420121529.htm. 

https://www.sciencedaily.com/releases/2021/04/210420121529.htm

For my current event, I chose to review the article “Forensic Puzzle Cracked via Fluid Mechanical Principles,” whose information came from the American Institute of Physics. The “forensic puzzle” referenced in the title is how a person’s clothes manage to stay clean even after they have shot someone. The research presented in Physics of Fluids includes “...​​theoretical results revealing an interaction of the incoming vortex ring of propellant muzzle gases with backward blood spatter”. Alexander Yarin, a distinguished professor at the University of Illinois at Chicago, stated that the name of this “...physical mechanism of backward spatter” is the Raleigh-Taylor instability, which is also the effect that occurs when water drips from a ceiling. Yarin, along with other researchers, was able to determine that this backward spatter was triggered by the acceleration of a denser fluid (blood) towards a lighter fluid (air). Because backward spatter droplets fly from the victim toward the shooter after being hit by a penetrating bullet, the researchers decided to focus on how droplets of blood interact with the turbulent vortex ring of muzzle gases moving from the shooter toward the victim. They predicted that blood droplets could get caught up in the flow of the turbulent vortex ring, and could even be turned around. As a result, the blood spatters end up either on the victim or behind them, leaving the shooter free of any physically incriminating evidence (besides the murder weapon of course). 

The information discovered in this study will be helpful in the future for the forensic analysis of murder or other criminal cases. One situation brought up in the article where this type of analysis could be used was the 2003 murder of actress Lana Clarkson, who was shot in the face from a short distance. The person who was ultimately convicted for her murder in 2009, music producer Phil Spector, did not have a single spatter of blood on his white clothing, even though there was significant blood spatter at the crime scene itself. At the time, the cause of this lack of blood spatter was a mystery, but we now know that blood spatters can sometimes fly backwards, leaving the shooter completely unscathed. Now, using fluid mechanical principles, cases such as these can be solved in a more timely and accurate manner. 

This article was very strong overall, as it provided significant information and specific quotes and details from one of the researchers who was actually part of the study and an author of Physics of Fluids. However, the scientific language used in the article was a bit hard to understand at times, as I didn’t know what some of the terms meant. I would suggest that the author go into more detail on what some of these words mean, in order to make the article easier to understand for the reader. This piece was a very interesting read and completely surprised me, as I had no idea that blood spatters could even go backwards or the positive implications this study held for the future of forensic analysis.