Bloodstain Pattern Interpretation

MacDonell, Herbert L.

doi:10.1002/9780470061589.fsa066

Cited by 18 publications

(26 citation statements)

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“…To take these forces into account, the impact velocity is required; a possible avenue is to try to determine this velocity from the size and volume of the bloodstains. Such an approach would allow for a much more accurate reconstruction of events, in contrast to the straight-line approximations that are currently used [7,8].…”

Section: Introductionmentioning

confidence: 99%

Maximum Diameter of Impacting Liquid Droplets

et al. 2014

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The maximum diameter a droplet that impacts on a surface will attain is the subject of controversy, notably for high-velocity impacts of low-viscosity liquids such as water or blood. We study the impact of droplets of simple liquids of different viscosities, and a shear-thinning complex fluid (blood), for a wide range of surfaces, impact speeds, and impact angles. We show that the spreading behavior cannot simply be predicted by equating the inertial to either capillary or viscous forces, since, for most situations of practical interest, all three forces are important. We determine the correct scaling behaviors for the viscous and capillary regimes and, by interpolating between the two, allow for a universal rescaling. The results for different impact angles can be rescaled on this universal curve also, by doing a simple geometrical correction for the impact angle. For blood, we show that the shear-thinning properties do not affect the maximum diameter and only the high-shear rate viscosity is relevant. With our study, we solve a longstanding problem within the fluid-dynamics community: We attest that the spreading behavior of droplets is governed by the conversion of kinetic energy into surface energy or dissipated heat. Energy transfer into internal flows marginally hinders droplet spreading upon impact.

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Section: Introductionmentioning

confidence: 99%

Maximum Diameter of Impacting Liquid Droplets

et al. 2014

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“…Similarly [15] verifies experimentally that the stringing method -over-estimates the point of origin and the error associated with this technique is significant (50% on average).‖ Such error is significant enough to wrongly conclude that a person was standing when in fact they may have been sitting. BPA experts are well aware that the area of origin is determined in an approximate sense [4], either as a maximum height from where the drops could originate, or -within the volume of a grapefruit, or even a basketball‖. This level of accuracy is considered satisfactory for many crime scene reconstruction purposes [4].…”

Section: (B) (B)mentioning

confidence: 99%

“…BPA experts are well aware that the area of origin is determined in an approximate sense [4], either as a maximum height from where the drops could originate, or -within the volume of a grapefruit, or even a basketball‖. This level of accuracy is considered satisfactory for many crime scene reconstruction purposes [4].…”

Section: (B) (B)mentioning

confidence: 99%

“…For instance, Balthazard et al mention [42] that their results are only valid for impact on a specific type of cardboard paper. In [4,119], MacDonell writes about how the substrate roughness can increase spatter, i.e. promote splashing.…”

Section: Normal Impactmentioning

confidence: 99%

“…First, section 2 describes the physical forces driving the dynamics -the motion and its causes-of blood as a fluid. Then, the formation of bloodstains is described as a deterministic sequence of events, in separate sections on (3) drop generation, (4) drop trajectories, (5) drop impact, and (6) stain formation.…”

Section: Introductionmentioning

confidence: 99%

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Fluid dynamics topics in bloodstain pattern analysis: Comparative review and research opportunities

Attinger

Moore

Donaldson

et al. 2013

Forensic Science International

154

139

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This comparative review highlights the relationships between the disciplines of bloodstain pattern analysis (BPA) in forensics and that of fluid dynamics (FD) in the physical sciences. In both the BPA and FD communities, scientists study the motion and phase change of a liquid in contact with air, or with other liquids or solids. Five aspects of BPA related to FD are discussed: the physical forces driving the motion of blood as a fluid; the generation of the drops; their flight in the air; their impact on solid or liquid surfaces; and the production of stains. For each of these topics, the relevant literature from the BPA community and from the FD community is reviewed. Comments are provided on opportunities for joint BPA and FD research, and on the development of novel FD-based tools and methods for BPA. Also, the use of dimensionless numbers is proposed to inform BPA analyses. Keywordsbloodstain pattern analysis, review, dimensionless number, drop generation, trajectory, impact, stain Disciplines Laboratory and Basic Science Research | Other Mechanical EngineeringComments NOTICE: this is the author's version of a work that was accepted for publication in Forensic Science International. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Forensic Science International, [231, 1-3, (2013) Abstract: This comparative review highlights the relationships between the disciplines of bloodstain pattern analysis (BPA) in forensics and that of fluid dynamics (FD) in the physical sciences. In both the BPA and FD communities, scientists study the motion and phase change of a liquid in contact with air, or with other liquids or solids. Five aspects of BPA related to FD are discussed: the physical forces driving the motion of blood as a fluid; the generation of the drops; their flight in the air; their impact on solid or liquid surfaces; and the production of stains. For each of these topics, the relevant literature from the BPA community and from the FD community is reviewed. Comments are provided on opportunities for joint BPA and FD research, and on the development of novel FD-based tools and methods for BPA. Also, the use of dimensionless numbers is proposed to inform BPA analyses.

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Serology: Bloodstain Pattern Analysis

Wolson

2016

Encyclopedia of Forensic and Legal Medicine

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Bloodstain Pattern Interpretation

Cited by 18 publications

References 0 publications

Maximum Diameter of Impacting Liquid Droplets

Maximum Diameter of Impacting Liquid Droplets

Fluid dynamics topics in bloodstain pattern analysis: Comparative review and research opportunities

Serology: Bloodstain Pattern Analysis

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