Investigation of blood dynamics: surface flow and droplet stain morphology on fabrics

Nik Elena Nik Mohamed

    Research output: ThesisMaster's Thesis

    276 Downloads (Pure)

    Abstract

    This thesis is divided into two parts, each of which examines aspects of bloodstain analysis where gravity is the main force applied to blood. Part I is a preliminary study on the dynamics of blood flow on various inclined surfaces and examines the use of blood analogs for easy test replication. The flow of uncoagulated human blood at different volumes and temperatures was examined on wood at a set angle of 1.5°, and on glass at varying incline angles. Glycerol solutions of 59% and 42% were used to represent blood at 23°C and 37°C respectively. Glycerol flow trials of similar volumes were conducted on wood, PVC and glass. Fluid flow plots of distance versus time exhibited double exponential curve behaviour, although a power-law relationship derived by H. E. Huppert's (1982) flow expression was obtained for blood flowing on inclined wood. Blood flow exhibited several observable characteristics; a decreasing width of the leading edge over time, and streaking and component separation of the leading region at very low speeds. On a glass surface, the width of the initial flow region decreased and initial speed increased with increasing angles. The glycerol analogs used in this study did not represent their blood counterparts well due to differences in physical properties of the fluids. Part II of this study focuses on the forensic value of passive bloodstains on three fabrics; 100% cotton drill, 65/35 polyester cotton, and 100% Shantung silk. 26 μL drops of 37°C human blood were deposited onto the three fabrics and paper from a height of 14 cm at various impact angles. The stains were photographed and analysed qualitatively and quantitatively using computational methods. 100% cotton drill, 65/35 polyester cotton and ironed 100% Shantung silk provided useful forensic values such as direction of travel and angle of impact. Overall, this study has provided useful preliminary data for further research work.
    Original languageEnglish
    QualificationMasters
    Publication statusUnpublished - 2009

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