An application of spray painting

Simulation of near bell paint break-up in electrostatic painting

PhD student: Björn Andersson, Fraunhofer-Chalmers Centre/Chalmers
Supervisor: Lars Davidson
Co-supervisor: Valeri Golovichev, Chalmers
Industrial co-supervisor: Andreas Mark, Fraunhofer-Chalmers Centre
Sponsors: Fraunhofer-Chalmers Centre, Vinnova
Publications: [1-4]
Start of project: November 2009

Paint and surface treatment processes in the car paint shop are to a large extent automated and performed by robots. Having access to tools that incorporate the flexibility of robotic path planning with fast and efficient simulation of the processes is important to reduce the time required for introduction of new car models, reduce the environmental impact and increase the quality.

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.

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

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Ingalena Ljungström