In this dissertation, a study of the atomization mechanisms in the immediate moments after impact on a film of blood is presented.
Both blunt and projectile impacts have been examined using high-speed imaging, which show distinct drop breakup characteristics due to ligament formation and high velocity impact. Digital in-line holography (DIH), in conjunction with high-speed imaging at kHz-rates, was used to quantify drop diameters and velocities milliseconds after impact. The Sandia HOLOSAND code was utilized to process holograms and identify droplet trajectories over multiple frames, thus improving overall out-of-plane accuracy of position and velocity estimation. The merits of DIH over traditional backlit imaging in terms of three-dimensional measurement is significant. The temporal evolution of blood droplets in blunt impact (flat-to-flat surface) at up to 4 m/s is reported and comparisons are made with water as a reference fluid. The characteristic velocities and diameters of blood droplets from a bullet impact are also reported. This quantitative dataset would be helpful in verification of theoretical models of droplet trajectories, which is a positive step towards connecting BPA and fluid dynamics communities. (Published abstract provided)
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