In spray painting paint primer, color layers and clear coating are applied through the Electrostatic Rotary Bell Sprayer (ERBS) technique. Paint is injected at the centre of a rotating bell; the paint forms a film on the bottom side of the bell and is atomized at the edge. In the current version of the FCC software IPS Virtual Paint the atomization step is not simulated instead measurements of droplet size and velocity distributions close to the bell are required as input.

PROJECT
In order to reduce the costly near-bell measurements, simulations of the initial break-up of paint into droplets forming a spray after exiting the bell will be performed. The break-up is a complex process with large relative velocities between the paint and the surrounding air flow, and in addition the rheology of the paint material may be complicated. Furthermore, strong electrostatic fields may be present affecting the atomization process.

The objective is to predict the size and velocity distributions of the droplets at some small distance away from the bell where the break-up is completed. To achieve this, the Lagrangian method Smoothed Particle Hydrodynamics (SPH) is chosen for the liquid paint phase. The larger volume fraction of the air part is on the other hand handled with an Eulerian Finite Volume solver. In the project the two discretization methods are coupled and models of the relevant physics in the paint break-up are developed and implemented.
 

1. Virtual Paint Shop - Spray Painting
    
   
2. B. Andersson, S. Jakobsson, A. Mark, L. Davidson, F. Edelvik
   Modeling Surface Tension in SPH by Interface Reconstruction using Radial Basis Functions, 5th international SPHERIC workshop, Manchester, UK, June 2010.
   View PDF file
    
   
3. Andersson, B.
   "Droplet Breakup in Automotive Spray Painting", thesis of Lic. of Engng, Division of Fluid Dynamics, Dept. of Applied Mechanics, Chalmers University of Technology, Göteborg, Sweden, 2012.
   View PDF file of thesis
    
   
4. B. Andersson, V. Golovitchev, S. Jakobsson, A. Mark, F. Edelvik, L. Davidson, J. S. Carlson
   Modified TAB Model for Viscous Fluids applied to Breakup in Rotary Bell Spray Painting, ICLASS 2012, 12th Triennial International Conference on Liquid Atomization and Spray Systems, Heidelberg, Germany, September 2-6, 2012.
   View PDF file