Premium
Predicting the Position of the Source of Blood Stains for Angled Impacts
Author(s) -
Knock Clare,
Davison Marie
Publication year - 2007
Publication title -
journal of forensic sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.715
H-Index - 96
eISSN - 1556-4029
pISSN - 0022-1198
DOI - 10.1111/j.1556-4029.2007.00505.x
Subject(s) - stain , drop (telecommunication) , position (finance) , materials science , geometry , analytical chemistry (journal) , mechanics , chemistry , physics , mathematics , chromatography , staining , biology , computer science , telecommunications , genetics , finance , economics
Droplets of pig’s blood were dropped onto paper at different angles to the horizontal to produce blood stains. Impact velocities varied from 1.82 to 5.76 m/sec, drop size from 3.7 to 5.0 mm in diameter, and the surface sloped at angles between 22.7° and 90° to the horizontal. From the data a single equation relating stain size to drop size and velocity for all impact angles was produced; ab = 111.74 (Re 1/2 We 1/4 ) 0.75 D o D o + 0.00084 with R 2 = 0.88, where a is the stain width, b the stain length, Re the Reynolds number, and We the Weber number. A second equation related the number of spines, N , to drop size, velocity, and surface slope for all impact angles as N = 0.76 We 0.5 sin 3 θ with R 2 = 0.9, where θ is the impact angle. Combining these equations the impact velocity can be determined and hence the position of the stain’s source.