High Velocity Oxygen Fuel Process (HVOF) involves supersonic two-phase flow of gas-solid particles. Two kinds of shocks are formed in a typical HVOF process. Adjustment of the over-expanded flow to the atmospheric pressure at the exit of the nozzle results in formation of shock diamonds while high speed flow impingement on a substrate creates bow shock. The latter is found to be responsible for deviation of the injected particles from their trajectories near the substrate which significantly reduces the chance of some particles landing on the substrate. An attempt is made to study the behavior of particle trajectory as it interacts with the bow shock formed near the substrate. The strength and location of bow shock was found to vary for different substrate geometries and stand-off distances. In this work, various particle sizes impinging on substrates with various configurations (flat, concave and convex) are simulated and the effect of shock diamonds and bow-shock, on particle trajectory is studied.