How important is it to consider target properties and hematocrit in bloodstain pattern analysis?

Kim, Sun-Gu; Ma, Youguang; Agrawal, Prashant; Attinger, Daniel

doi:10.1016/j.forsciint.2016.05.015

Cited by 20 publications

(25 citation statements)

References 23 publications

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“…Meanwhile, in 2016, Kim al. investigated the influence of the target properties on the trajectory reconstruction of blood 295 droplets impacting different surfaces using glass, polycarbonate bare, aluminium mirror and cardstock [16]. To quantify the influence, they correlated the Ohnesorge number (Oh = √ W e/Re), which relates the energy of the impact to the resistant work of surface tension and viscous 300 forces, to the spreading ratio.…”

Section: Surface Influencementioning

confidence: 99%

Wetting and spreading of human blood: Recent advances and applications

Smith

Brutin

2018

Current Opinion in Colloid & Interface Science

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Investigation of the physical phenomena involved in blood interactions with real surfaces present new exciting challenges. The fluid mechanical properties of such a fluid is singular due its non-Newtonian and complex behaviour, depending on the surrounding ambient conditions and the donor/victim's blood biological properties. The fundamental research on the topic remains fairly recent; although it finds applications in fields such as forensic science, with bloodstain pattern analysis, or biomedical science with the prospect of disease detection from dried blood droplets. In this paper, we review the understanding that has been achieved by interpreting blood wetting, spreading and drying when in contact, ex-vivo, with non-coated surfaces. Ultimately, we highlight the applications with the most up to date research, future perspectives, and the need of advancing further in this topic for the benefit of researchers, engineers, bloodstain pattern analysts, and medical practitioners.

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Section: Surface Influencementioning

confidence: 99%

Wetting and spreading of human blood: Recent advances and applications

Smith

Brutin

2018

Current Opinion in Colloid & Interface Science

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“…Results are not directly applicable to stains found on a vertical wall or on the ceiling. f) The spreading of stains on the non-absorbing target of interest is similar to that characterized on smooth cardstock [3]. g) The stain ellipticity is a simple function of the impact angle, shown in Figure 1, for any fluid dynamic conditions.…”

Section: The Problem Inmentioning

confidence: 79%

“…Uncertainties related to fluid dynamic conditions on the determination of the impact angle from stain inspection have been investigated quantitatively [2]. The fate of a dripping drop was characterized as a function of the impact conditions, with respect to spreading on various target materials [3]. Quantitative measurements were made of the wicking, rotation and deformation of stains caused by fabrics [4].…”

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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“…It should be emphasized that the Ohnesorge number involves viscosity μ blood , which was taken as the asymptotic value obtained in the simple shear flow, μ blood = 5 mPa × s [27], because high shear rates accompany droplet spreading on impact [48,49]. This leads to the following expression for the FIG.…”

Section: Resultsmentioning

confidence: 99%

“…As such, it is nearly impossible to really prove that one correlation is better or more appropriate than the other unless the correlation is tested and found for each possible deposition scenario. Note also that using the dependence of the blood viscosity on temperature and hematocrit from [49] and of the surface temperature of blood on temperature from [53], it was found that the theoretical predictions of the dependence of the average stain area on distance (cf. Fig.…”

Section: Resultsmentioning

confidence: 99%

Theoretical and experimental investigation of forward spatter of blood from a gunshot

2018

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A theoretical model predicting forward blood spatter patterns resulting from a round nose bullet gunshot wound is proposed. The chaotic disintegration of a blood layer located ahead and aside of the bullet is considered in the framework of percolation theory. The size distribution of blood drops is determined, which allows for the prediction of a blood spatter cloud being ejected from the rear side of the target where the bullet exits. Then, droplet trajectories are numerically predicted accounting for gravity and air drag, which is affected by the collective aerodynamic interaction of drops through air. The model predicts the number and area of individual stains, as well as the stain distribution as a function of distance from the region of origin. The theoretical predictions are compared with experimental data acquired in this work from 9 mm Luger copper full metal jacket bullets fired from a handgun. The agreement between the predicted and experimentally measured parameters is found to be good. Disciplines

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How important is it to consider target properties and hematocrit in bloodstain pattern analysis?

Cited by 20 publications

References 23 publications

Wetting and spreading of human blood: Recent advances and applications

Wetting and spreading of human blood: Recent advances and applications

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 and experimental investigation of forward spatter of blood from a gunshot

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