A Numerical Analysis on the Correlation Between Impact Conditions of Blood Drop on the Wall and its Resulting Bloodstain Pattern

At the crime scene in case of homicide, spattered bloodstains at the incident site are important evidence. The patterns of the bloodstain on the floors and walls are determined by the impact conditions of blood drop such as drop size, impact angle and velocity. By analyzing the bloodstain pattern, one can retrace the origin of blood drops to reconstruct the crime scene. In the present study, motions of blood drop are analyzed to figure out the correlation between impact conditions of blood drop and bloodstain patterns. Two phase interfacial flows of blood drop impacting the wall are numerically simulated with the VOF method. To get the accurate results of bloodstains on the wall, non-Newtonian fluid viscosity and dynamic contact angle are used as the blood properties. By using these methods, patterns of bloodstains created from the blood drop are predicted for various Reynolds and Weber numbers.