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Charts Based on Millions of Fluid Dynamics Simulations Provide a Simple Tool To Estimate How Far From Its Source a Specific Blood Stain Can Be Found

NCJ Number
254149
Journal
Forensic Science International Volume: 298 Dated: May 2019 Pages: 97-105
Date Published
May 2019
Length
9 pages
Author(s)
Daniel Attinger
Annotation

This article reports on the production and mining of a large dataset of just over five million of numerically calculated trajectories of blood drops, so as to determine the maximum distance between a blood stain and the source of the blood.

Abstract

The bloodstain pattern analyst sometimes must determine whether a given stain could originate from a specific location. A wide range of values of the maximum distance that a blood drop can travel have been reported from experiments, ranging from less than 1 meter to more than 10 meters. The current project formulated the problem in a fluid dynamics and data mining framework. The fluid dynamics was solved with Newton's classical equation of motion coupled with well-established models for the gravity and drag forces that bend the trajectories of drops. The parameters screened were the drop size, initial velocity and launch angle, as well as the height of a blood source and the ceiling height. Combining a wide range of values of those five parameters commended the performance of more than 5 million fluid dynamic simulations. Results of these simulations have been searched and mined for parameters directly measurable on a crime scene, such as the stain size and stain ellipticity. The results are presented in simple, easy to use charts, which do not require any knowledge of fluid dynamics from the analyst. (publisher abstract modified)

Date Created: December 21, 2021