Spray Injection: DPM

Description: This project simulates a water spray issuing from a small circular inlet into a larger cubic enclosure, tracking the behavior of the spray particle by particle, and serves as a standard introduction to the Discrete Phase Model — the Lagrangian approach Fluent uses when the goal is to resolve the trajectory, velocity, and dispersion of individual droplets rather than treating the spray as a continuous second phase.

Methodology: The geometry is a rectangular cube with a circular inlet on the top wall, built in Design Modeler and meshed in ANSYS Meshing with an unstructured grid of 25,464 cells. Because droplets move discretely through a continuous medium, the case couples a Lagrangian DPM with the continuous Eulerian air flow and is run as transient to capture how the spray develops over time. Water is released as a surface injection from the inlet, with droplets treated as inert particles, specifying how, where, and at what size and velocity the particles enter so Fluent can integrate each trajectory through the flow field.

Analysis: Results include velocity and mass-concentration contours of the water particles at the final time step, along with 3-D particle tracks colored by speed and droplet diameter. The tracks confirm the injection behaves as expected, with droplets dispersing discretely from the top inlet and distributing through the enclosure — the kind of behavior relevant to sizing nozzles or predicting spray coverage in practical applications.