Multi-step ice accretion on complex three-dimensional geometries

Abstract. This work presents the Politecnico di Milano Icing Research Group's contribution to developing new numerical tools and methodologies for simulating long-term in-flight icing over complex three-dimensional geometries. PoliMIce is an in-house ice accretion software that includes state-of-the-art solvers for the dispersed phase to compute the droplets’ impact on the aircraft, and ice accretion models, including the exact local solution of the unsteady Stefan problem. PoliMIce has also been extensively developed for the simulation and robust design optimization of thermal ice protection systems. A crucial aspect that characterizes and makes numerical simulations challenging is the formation, and evolution in time of complex ice geometries, resulting from the ice accretion over the body surface and/or previously formed ice. A multi-step procedure is implemented since the aerodynamic flow field is coupled with ice accretion. The total icing exposure time is subdivided into smaller time steps. At each time step, a three-dimensional body-fitted mesh suitable for the computation of the aerodynamic flow field around the updated geometry is generated automatically. The novel remeshing procedure is based on an implicit domain representation of the ice-air interface through a level-set method and Delaunay triangulation to generate a new conformal body-fitted mesh. In this work, the unique capabilities of the PoliMIce suite are employed to perform automatic multi-step ice accretion simulations over a swept wing in glaze ice conditions. Numerical simulations are hence compared with the available experimental data.