Water Evaporation CFD Method with the Meshfree Volume-Volume-Coupling Approach for Wet Automotive Component Dry-Out Time Prediction

A new two-phase mass transfer Computational Fluid Dynamics (CFD) method is developed using a meshfree collocation approach, or Generalized Finite Difference Method (GFDM), to resolve the evaporation phenomenon at the waterair interface since it is essential to estimate the water dry-out-time for corrosion protection schemes on automotive components. Thereby, the volume-volume-coupling to couple the phases – air and water – is used in order to keep a stable phase interface. At the interface, it is assumed that the main driving force of the liquid mass transfer into vapor is diffusion driven by the vapor concentration gradient. The automatized adaptive refinement based on the humidity- and velocity-gradient enabling the automation of the whole process is also developed. The newly developed method is validated with one simple and actual vehicle geometries. In vehicle geometry case, the total-dry-out times of an accumulated water source at the corner of a sunroof are measured. In order to extend the time scale of the simulation to real, the water reduction rate at the free surface is artificially accelerated once the evaporation rates are quasi stabilized. The validation results are promising, and the method could be extended into further complex vehicle applications.