Experimental validation of a numerical model for predicting the trajectory of blood drops in typical crime scene conditions, including droplet deformation and breakup, with a study of the effect of indoor air currents and wind on typical spatter drop trajectories

Kabaliuk, Natalia; Jermy, Mark; Williams, E.G.; Laber, Terry L.; Taylor, Michael

doi:10.1016/j.forsciint.2014.10.020

Cited by 21 publications

(26 citation statements)

References 33 publications

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“…Fundamental consistencies in the stages of blood drop generation and release were observed in both the fixed-spinning device and human-wielded objects. These phenomena are consistent with those described by Kabaliuk et al (18) and with descriptions of rotary atomization (16,17). Cast-off blood typically arose from blood ligaments extending outward from the object endpoints.…”

Section: Discussionsupporting

confidence: 92%

“…It is evident that each drop's linear trajectory is approximately tangential to the circular trajectory of the knife tip at the moment that drop was released. The same blood ligament development and droplet break‐off processes were reported by Kabaliuk et al , using a motorized blood droplet generation device developed by Williams and Taylor .…”

Section: Resultssupporting

confidence: 60%

“…The simple example of the bloodied knife rotating on the fixed apparatus was expected to exhibit the same rotary atomization dynamics as the motorized rotating disk reported by Kabaliuk et al and Williams et al . These apparatus, as well as that of Kunz et al, had a fixed radius length and stationary center of rotation.…”

Section: Discussionmentioning

confidence: 55%

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The Dynamics of Blood Drop Release from Swinging Objects in the Creation of Cast‐off Bloodstain Patterns

Williams

Graham

Jermy

et al. 2018

Journal of Forensic Sciences

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Although the characteristics of cast-off bloodstain patterns are well known, the physics of the mechanism by which they are created is poorly understood. The aim of this work was to describe the process by which blood droplets disengage from swinging objects. Cast-off droplets were recorded using high-speed digital video photography, and the resulting cast-off patterns were analyzed to draw inferences about the trajectories of individual drops. Blood on the object's distal end formed ligaments, which subsequently disintegrated into droplets. Initial droplet trajectories were approximately tangential to the trajectory of the location on the object from which the droplet was released. The application of the laws of physics to the mechanism of cast-off is discussed, and the process of drop formation is compared to that of passive drop formation. A technical description of cast-off is proposed, and a diagram to aid investigators in interpreting cast-off patterns at crime scenes is offered.

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Section: Discussionsupporting

confidence: 92%

Section: Resultssupporting

confidence: 60%

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The Dynamics of Blood Drop Release from Swinging Objects in the Creation of Cast‐off Bloodstain Patterns

Williams

Graham

Jermy

et al. 2018

Journal of Forensic Sciences

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“…Its properties have been further characterized in terms of storage life [12] and extensional viscosity [13]. Trajectory models accounting for the effect of drag and gravity on drops were formulated and calibrated [14,15]. Many of the rationale for these research efforts can be justified by the multiple and natural connections between fluid dynamics and bloodstain pattern analysis [16].…”

Section: Accepted Manuscriptmentioning

confidence: 99%

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

Attinger

2019

Forensic Science International

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The bloodstain pattern analyst sometimes has to judge if 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 one meter to more than 10 meter. Here we formulate the problem in a fluid dynamics and data mining framework. The fluid dynamics is 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 are 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 parameter commended the performance of more than 5 million fluid dynamic simulations. Results of those 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 charts. Those charts are easy to use, and do not require any knowledge of fluid dynamics from the analyst. Disciplines Aerodynamics and Fluid Mechanics | Forensic Science and Technology | Mechanical Engineering Comments This is a manuscript of an article published as Attinger, Daniel. "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."

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“…They include, among many others, forensic applications (Kabaliuk et al 2014), solvent extraction (Petera et al 2007), electrostatic enhancement of liquid-liquid contacting processes (Petera et al 1997), ink-jet printer design (Mohebil and Evans 2005), spray modeling (Sinha et al 2015, Taskiran andErgeneman 2014), and design of nuclear fusion subsystems (Yang et al 2013).…”

Section: Tecnological Aspectsmentioning

confidence: 99%

Theoretical model for droplet deformation and trajectory in continously accelerating flows

Mendi¹

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Experimental validation of a numerical model for predicting the trajectory of blood drops in typical crime scene conditions, including droplet deformation and breakup, with a study of the effect of indoor air currents and wind on typical spatter drop trajectories

Cited by 21 publications

References 33 publications

The Dynamics of Blood Drop Release from Swinging Objects in the Creation of Cast‐off Bloodstain Patterns

The Dynamics of Blood Drop Release from Swinging Objects in the Creation of Cast‐off Bloodstain Patterns

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

Theoretical model for droplet deformation and trajectory in continously accelerating flows

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