Ice Shape Convergence in Multi-Step Ice Accretion Simulations over Straight Wings

Abstract

Local errors in the geometrical description of the ice front are amplified in multi-step simulations over conformal meshes due to the coupling of aerodynamics, water impingement, ice accretion, and grid deformation. Small perturbations in the initial phase of ice formation possibly result in dramatically different ice shapes which can hinder the stability of the multi-step procedure. This problem is analyzed by investigating the combined effects of space and time discretization on the ice growth over airfoils and three-dimensional wings. We propose an automatic procedure for selecting the time interval for the update of the aerodynamics and particle impingement. A local growth limiter 𝜆 is introduced here to bound the local ice thickness growth to be comparable to the local grid spacing on the surface, resulting in an automatic adaptive time-step to be used in the multi-step simulation. Examples are provided for three-dimensional cases under both rime and glaze conditions over straight wings. These examples highlight the different accretion mechanisms of the two ice regimes and preliminary indicate that ice-shape convergence can be achieved for low values of 𝜆.