The objective of this research project is to assess and enhance the ability of a recentlyadvanced high-fidelity modeling framework for spray formation to model complex liquid break-up and predict drop size distributions in high viscosity and non-Newtonian liquid atomization systems, such as found in spray drying applications. This framework, which has been developed by the PI’s research group, hinges on two key components: (1) a fully conservative Eulerian interface tracking technique with the ability to capture sub-grid scale liquid features such as thin films and thin ligaments, known to be of critical importance in the break-up of viscous and non-Newtonian fluids, and (2) simple physics-based break-up models to convert these thin liquid features into spray droplets that can be tracked in a Lagrangian fashion.
The focus of the work to date has been studying how complex fluid rheology (e.g., liquids with high viscosity and non-Newtonian behavior) alters atomization physics. Preliminary analysis of high viscosity liquid atomization in a pressure-swirl configuration has shown conventional liquid-gas interface techniques lead to break-up that is not physicsbased (i.e., the break-up is caused by numerical errors) while our newly developed interface tracking method is able to maintain the thin-conical sheet that occurs during pressure-swirl atomization of high viscosity liquids. Additionally, non-Newtonian constitutive models have been implemented and tested in benchmark flow configurations with initial verification and validation matching published works. These models were implemented in a smaller scale flow configuration and were shown to have significant impact on liquid structure break-up, and for the case of high viscosity liquids, impact the mean droplet size.
Going forward, the focus will be to continue studying how complex rheology impacts liquid structure break-up and using those lessons and observations as guidance for how our current model can be adapted to account for complex liquid rheology. An updated model will then be implemented in large-scale, industrial-type atomization systems, which in turn, will allow for comparison will experimental measurements for drop size distributions.