Development of an OpenFOAM solver for particle migration in the casting process of solid rocket motors

The aim of this thesis work is the study the solid particles migration phenomenon in concentrated suspension and the development of an OpenFOAM solver able to successfully predict the behaviour of such event. It is, in fact, common knowledge how the solid particles will tend to spread into an heterogeneous arrangement when the fluid is subjected to a non-uniform shear flow. As a consequence, the viscosity field will become uneven as well, giving rise to a non-Newtonian behaviour of the flow. In order to approach the problem, the OpenFOAM transient solver pimpleFoam has been modified, changing the implementation of the equation of motion to make it suitable for a variable viscosity field. Additionally, an iterative cycle for the resolution of the partial differential equation describing the particle migration process has been included in the algorithm. The model chosen to describe the viscosity field is the Krieger’s correlation, which consists of a power law linking the local volume fraction to the dynamic viscosity of the fluid. For the validation of the solver a bidimensional channel flow has been selected; the results of the simulation will be compared to experimental measurements and data provided by a 1D and a 2D finite volume implementations of the model from literature. Following the global trend deduced from the experiment, the distribution profile predicted via OpenFOAM also proved to follow in a quite satisfactory way the results of the 2D model. Subsequently a mesh sensitivity analysis is going to be performed in order to understand how is the solution affected by employing coarser discretizations.