Conventional methods of classifying droplet breakup are evaluated in the context of unique variation in environmental and droplet fluid conditions. Most characterization is developed for subsonic speeds and Newtonian fluids, so this study extends understanding on how these forms change to a span of applications outside these conditions. Presented examples include the impact effects on hypersonic vehicles travelling through precipitation, where even smallest of rain drops at such speeds can cause damage. Before the droplet even reaches the vehicle, it interacts with the detached bow shock that leads it. Another example of exceptional recent concern is risk of viral transmission by breakup function within human saliva in sneezes, coughs and speaking. Such biofluid behavior is complicated by viscous and elastic properties, subject to molecular composition that varies person to person by function of their age, gender, and medical conditions. Both phenomena are difficult to image on the scale of internal droplet fluid flow and droplets of aerosolizing diameters. Thus, this study uses a multi-stage model that couples full scale simulations to simulations of a droplet scale. This multi-scale modelling approach develops a low cost computational method for system evaluation. The hypersonic impact model explores droplet breakup physics that resolve shock transmission through the droplet, with analysis of breakup driving factors of evaporation and cavitation. Similar studies are examined for the viscoelastic breakup of ejected saliva. The results indicate neither example can use conventional methods to characterize the droplet breakup seen. Droplets interacting with a shock experience internal fluid dynamics that present before the expected breakup form. Droplets of viscoelastic nature do not reach the expected breakup form, instead snapping back to prior shape. The results indicate that further experimental and simulation work is needed to address these unique conditions.
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Master of Science in Aerospace Engineering (M.S.A.E.)
College of Engineering and Computer Science
Mechanical and Aerospace Engineering
Aerospace Engineering; Thermofluid Aerodynamic Systems
Length of Campus-only Access
Masters Thesis (Open Access)
Anderson, Caroline, "Computational Studies for Extending Understanding of Complex Droplet Breakup Mechanisms" (2021). Electronic Theses and Dissertations, 2020-. 639.