A computational fluid dynamic model of the cold gas dynamic spray process is presented. The gas dynamic flow field and particle trajectories within an oval shaped supersonic nozzle as well as in the immediate surroundings of the nozzle exit, before and after the impact with the substrate, are predicted. The ultimate objective is to determine details of the pattern of particle release into the surroundings for particle collection considerations. The particles are assumed to be spherical in shape and the model used for drag force calculation takes into account Mach number effects. Due to the low concentration of particulate matter being simulated, the particle-particle interactions are considered to be negligible. A discrete-phase Lagrangian particle trajectory model is also assumed where the fluid motion is not affected by the particle drag. Heat transfer between the particle and the carrier gas is included as the critical velocity of a particle depends, to some extent, on its temperature at the time of impact. It is assumed that there is negligible internal resistance to heat transfer within the particle. The equations of impact dynamics as well as the hardness characteristics of the impact materials are used to determine the normal and tangential components of particle velocity after impact. It also is capable of giving an estimate of the deposition efficiency of the impact process.

Predicted particle velocity results at the nozzle exit are compared with experimental data. A forward-scatter laser Doppler anemometer with frequency shifting capability is used for this purpose. The numerical results are in qualitative agreement with the velocity profiles along the major and minor axis at the nozzle exit.  The locations and concentrations of particles leaving the boundaries of the domain of interest are determined and presented in a graphical manner that is easy to interpret.