Wall jets generate a high-intensity broadband noise compared to free jets. As discussed in the previous section, a wall jet flow can be related to a number of practical applications, from a simple household appliance to aerospace applications. The current scenario demands quieter flow appliances with lower noise emissions. For instance, the cabin noise of aircraft, high-speed locomotives, and automobiles is influenced by the outer flow and demands a detailed study to understand noise mitigation. Moreover, the prolonged exposure to flow noise is annoying that may cause serious psychological and health issues. Thus, according to the norms laid by the noise regulatory bodies, priority is given to the mitigation of acoustic emissions from flow-related appliances. Over the past few decades, significant noise reduction strategies have been accomplished by varying the surface conditions. The major noise emissions from wall jets are due to the interaction of a turbulent jet with a rigid wall and the trailing edge of the plate.
