Application of Smoothed Particle Hydrodynamics to simulate multi fluid flows with large density differences and application to mixing of paints

Application of Smoothed Particle Hydrodynamics to simulate multi fluid flows with large density differences and application to mixing of paints

Abstract


Liquid mixing and blending is an important operation before packaging a many fluid product. The blending or mixing process should be cheap and efficient and at the same time result in high product quality in terms of consistency. In order to achieve this goal experimentally one needs to perform many trials involving changes in the motion and geometric dimensions of the packaging container as well as product ratios of the fluid that is being blended together. Simulation can be used as an efficient tool to reduce the number of such experimental trials and/or optimise the system once a reasonable solution is obtained from the experimental trials.

There are three principle issues that arise while modelling such systems which can lead to difficulties for traditional grid-based CFD methods:

1. Tracking of the complex interface between the two phases as well as the free surface behaviour,
2. Dealing with complex motions of the packaging equipment
3. Dealing with large density differences between the fluids in consideration and
4. Tracking of convective movement of different fluid components.

In order to overcome these issues the mesh-free Smoothed Particle Hydrodynamics (SPH) method is explored as an alternative tool for modelling such systems. In this paper we develop a robust methodology to deal with fluids having a density ratio of up to 1:1000. We then demonstrate its application to the mixing of a viscous liquid in a container moving in a complex circular path with varying liquid levels. The simulations presented in this paper are performed in 2D. Extension to 3D and comparison with experimental results will be presented in a subsequent study.