Numerical investigation of local heat transfer characteristics of an oblique droplet impacting a wetted wall

Abstract

In this study, the flow dynamics and heat transfer process of a single droplet obliquely impacting a wall covered by a thin liquid film are investigated numerically based on the volume of fluid method, with the impact angle ranging from 0° to 45°. The results show that the flow and heat transfer for the oblique impact of a droplet show asymmetric pattern and differ significantly from those for a normal impact. The asymmetric heat transfer pattern for oblique impact of a droplet primarily lied in the asymmetric influenced area caused by asymmetric crown jets spreading on the bilateral sides and asymmetric heat transfer oscillation in the valley region caused by asymmetric recirculation. These asymmetries originate indirectly from the asymmetric droplet impaction energy transfer to the bilateral liquid film induced by the oblique impact angle. In addition, parametric studies suggest that the asymmetry of the heat transfer distribution becomes more significant for a larger oblique impact angle, higher Weber number, or smaller dimensionless film thickness. Keywords: Oblique, Droplet impact, Liquid film, Heat transfer, VOF