Incompressible Smoothed Particle Hydrodynamics Simulation Of Droplet Impact, Transforming And Solidification In Thermal Sprayed Coating

Smoothed Particle Hydrodynamics (SPH) is one kind of meshfree method that is developed rapidly in the last ten years. This method has high adaptability for capturing the complex fluid mechanics problem with large deformable domain and multiphase interface. In this dissertation, a meshfree numerical model based on the incompressible smoothed particle hydrodynamics (ISPH) is proposed for the process of droplet impact, transforming, spreading, heat-conducting and solidification on the substrate. Fourier's law holds for the heat conduction and van der Waals interaction is taken into account for the droplet surface tension. Droplet solidification is determined from the conservation of internal energy, and the solidification interface is predicted from the temperature distribution.This ISPH model is firstly validated with analytical solution of the Couette flow. Secondly, the Madjeski model of flattening ratio defined by the splat diameter and the droplet diameter is used to compare the numerical results of droplet impact. And both of above comparison show good agreement. Then, this tested ISPH model is applied to the thermal-sprayed droplets on different substrates, i.e., smooth or rough, perpendicular or inclined. The influence of roughness and incline angle on the flattening ratio is parametrically studied. Results show that the flattening ratio increases with the incline angle, and decreases as the substrate gets rougher.