Application of the Vof methodology for the analysis of transient shear rates in droplet-wall interaction

Abstract

Papers presented to the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 20-23 July 2015.

Sprays are very frequently utilized for the generation of an evenly distributed liquid film on a surface, e.g. in finishing or coating applications. The process liquids in this context usually exhibit a non-Newtonian behaviour, i.e. shear-thinning characteristics plus thixotropy. In order to be able to predict the flow inside the developing liquid film, the local instantaneous viscosities of the fluid need to be available, which are primarily influenced by the viscosity of the droplets deposited on the film surface. For shear-thinning liquids, this viscosity depends upon the transient shear rates occurring during the droplet-wall or better droplet-film interaction. The present paper describes activities applying the VOF methodology to predict the local instantaneous shear rates of droplet-wall interaction in a relevant range of Weber numbers.