LAUSR

A new computational method for droplet concentration was developed to efficiently predict droplet impact efficiency on airplane surface elements. The method computes concentration along a Lagrangian path in combination with a novel Eulerian approach for the particle velocity divergence. The combined approach is termed the globally Eulerian/locally Lagrangian approach. This method was compared to conventional ensemble-based and area-based approaches for impact efficiency in terms of accuracy and efficiency for an inviscid cylinder flow and a Reynolds-averaged Navier–Stokes-based airfoil flow. The globally Eulerian/locally Lagrangian method provided good agreement with analytical and experimental results and avoided the large number of particle paths needed for statistical convergence (unlike bin methods) while allowing extension to unsteady flowfields (unlike area-based methods).