Copyright © 2011 Tech Science Press FDMP, vol.7, no.3, pp.259-278, 2011 Modeling and Simulation of Sealing Spray Application Using Smoothed Particle Hydrodynamics Robert Rundqvist 1 , Andreas Mark 1 , Fredrik Edelvik 1 Johan S. Carlsson 1 Abstract: Multiphase flow simulation using Smoothed Particle Hydrodynamics (SPH) has gained interest during recent years, mostly due to the inherent flexibility of the method and the physically rather intuitive formulation of extra constitutive equations needed when dealing with for instance non-Newtonian flows. In the work presented here, simulations based on an SPH model implemented in the flow solver IBOFlow has been used for simulation of robotic application of sealing material on a car body. Application of sealing materials is done in order to prevent water leak- age into cavities of the body, and to reduce noise. In off-line programming of the robots in the automotive paintshop it is of great interest to predict shape and ap- pearance of sealing material without having to resort to trial and error procedures. The flow of sealing material in the air between applicator and target (car body) is relatively uncomplicated, as the material mostly moves at constant velocity until impact on target. The flow of the material on the target is however more com- plex, applied material flows at the target surface due to inertia, gravity and pressure and in order to predict the appearance of the applied material, flow equations for a non-Newtonian fluid with an open surface needs to be solved. The sealing ma- terial is both thixotropic and viscoelastic; the material is shear thinning but needs to be sheared for some time before the structure of the material is broken down. Conversely, the regain of structure of the material, and thereby also the increase of viscosity when shearing is stopped or reduced, is also connected to a delay time. In the model used, the local viscosity is considered obeying a first order differential equation where the stationary limit is determined by a Bingham relation. The simulation model was built by comparing simulations and experiments at three different stages of complexity. In the most fundamental stage the material proper- ties were determined. Using a rotational rheometer, yield stress, plastic viscosity and thixotropy time constant was determined and implemented in the simulation model. To verify the numerical behaviour of the rheology, simulated rheometer 1 Fraunhofer Chalmers Research Centre, Chalmers Science Park, SE-412 88 Göteborg, Sweden