Use of Skeletonization Techniques for the Analysis of Thin Structures in Multiphase Flows

Measurements of velocity, vorticity, and energy profiles have long been used for the analysis and validation of fluid flow simulations, but proper analysis of multiphase flow simulations requires the consideration of the geometric properties of the flow. Previous Volume-of-Fluid (VOF) studies reported on the statistical analysis of droplet sizes in primary atomization. We expand the analysis to the formation of ligaments and thin films. First, we apply standard methods of skeletonization used in image processing such as thinning and levelset methods to identify and localize thin films and ligaments from the VOF color function. We then measure the length, shape, and thickness of identified structures and perform deterministic and statistical analysis of these measurements. Last, we demonstrate the use of skeletonization techniques to improve the efficiency and physical accuracy of primary atomization simulations, using skeleton characteristics as criteria for adaptive mesh refinement and the identification of locations for film perforation. In the future, skeletons could also be used to replace thin structures with thin film asymptotic approximations which would greatly speed up simulations where the bottleneck is the large range of length scales in the fluid flow structures.