There is widespread industrial interest in wire arc spraying as it has proven to be a relatively inexpensive alternative providing high quality coatings in many applications. Modeling and experimental studies have been conducted with different nozzle geometries to study the influence of fluid dynamics on the behavior of the particles which form the coating. Schlieren optical diagnostics and image analysis are used to study flow patterns obtained with different nozzle geometries. Supplementary measurements are made with static and total pressure probes. A particle breakup model is used to predict the trajectory and breakup of molten particles in the jet. This investigation indicates that nozzle designs that minimize or eliminate shock formation before the atomizing gas reaches the wire tips result in lower coating porosity and a more uniform particle size distribution.