A numerical study on wind-driven runback characteristics of a thin water film flow over a solid surface

An unsteady numerical simulation is conducted to examine the dynamic runback characteristics of a water film flow driven by a boundary layer airflow over a solid surface pertinent to the dynamic glaze ice accretion process over aircraft wing surfaces. The multiphase flow simulation results of the wind-driven water runback (WDWR) flow are compared quantitatively with the experimental results in terms of the time-dependent variations of the water film thickness profiles and evolution of the front contact point of the runback water film flow. The underlying mechanism of the intermittent water runback behavior is elucidated by analyzing the time evolution of the airflow velocity and vorticity fields above the runback water film flow over the solid surface. To the best knowledge of the authors, the work presented here is the first successful attempt to numerically examine the transient runback characteristics of WDWR flows. It serves as an excellent benchmark case for the development of best practices to model the important micro-physical processes responsible for the transient water transport over aircraft wing surfaces.