Based on unstructured grids

the ice accretions on airfoils have been numerically simulated.The air flowfield was solved using the Euler equations.A permeable wall was used to simulate the droplet impingement on airfoils.An iterative method was developed to solve the governing equations for droplets.The collection efficiency was calculated from the droplet flowfield.The different freezing models corresponding to the rime and glaze ice were employed to simulate the freezing process.The process of ice accretions was simulated with the assumption that ice accumulates layer-by-layer and the ice shape was built with the assumption that ice grows in the direction normal to the airfoil surface.The rime and glaze ice accretions on a NACA 0012 airfoil were investigated and the comparison with the experimental data indicates that the numerical method proposed is effective.The effects of ice accretions on aerodynamic performance of the airfoil were also analyzed.