title: Predicting the position of the source of blood stains for angled impacts.
abstract: 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 degrees and 90 degrees 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)theta with R(2) = 0.9, where theta is the impact angle. Combining these equations the impact velocity can be determined and hence the position of the stain's source.
authors.affiliation: Engineering Systems Department, Cranfield University, Shrivenham, Swindon, Wilts SN6 8BB, UK. c.knock@cranfield.ac.uk
authors.forename: Clare
authors.initials: C
authors.lastname: Knock
authors.forename: Marie
authors.initials: M
authors.lastname: Davison
mesh_terms: D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D001801:Blood Stains; D005554:Forensic Medicine / Q000379:methods*; D008954:Models, Biological; D010781:Photography; D013552:Swine