Lagrangian and Eulerian algorithms for water droplets in in-flight ice accretion

A particle tracking framework for the computation of the collection efficiency for in-flight ice accretion is presented. Algorithms for the computation of the collection efficiency are presented for both Lagrangian and Eulerian descriptions of the droplets equations. Strengths and weaknesses of each method are analyzed and possible solutions are described and implemented. For the Lagrangian solver, a method for automatic resolution adaptation is introduced, and a strategy for exploiting parallelism is described. In the Eulerian frame a scheme is presented for the solution of the equations on unstruc-tured 3D grids using a relaxation approach. An hybrid Lagrangian Eulerian approach for the computation of the collection efficiency is also introduced which is relevant for Super-cooled Large Droplet condition. All presented algorithms are thoroughly verified, and a comprehensive validation is performed.