Spray: Air Freshener in a Restroom

Air Freshener Spray in Restroom CFD Simulation, ANSYS Fluent Training

Description

This project simulates air freshener spray within a restroom using ANSYS Fluent. The 3D geometry was designed in Design Modeler, representing the interior of a restroom, and meshed in ANSYS Meshing using an unstructured grid with the curvature method applied to focus refinement on grid-sensitive areas, totaling 1,187,006 cells.

Methodology

This project investigates air freshener spray behavior using the two-way DPM method. Fragrance particles are physically expelled from the device as water droplets that evaporate into the surrounding space, defined at a temperature of 310 K, a velocity of 50 m/s, and a mass flow rate of 0.018 kg/s, emitted over an interval of 0 to 0.1 seconds. Since droplet diameter isn't constant during diffusion, the Rosin-Rammler logarithmic distribution method was used to represent the resulting range of particle sizes, with minimum, maximum, and average diameters, the distribution's spread parameter, and the number of size classes per injection all determined through this formulation. This droplet-based approach required activating the Species Transport model alongside DPM.

Discrete phase boundary conditions were defined as Escape at the device outlet, the restroom inlet, and the toilet outlet — allowing particles to pass freely through these boundaries — while a Trap condition was applied at all walls and heater surfaces, capturing and collecting particles that reach these surfaces. The simulation was run as unsteady, using a time step of 0.01 seconds, with the RNG k-epsilon model and energy equation enabled to resolve turbulent flow behavior and temperature distribution throughout the domain.

Conclusion

The results show that the restroom's heater establishes a suitable ambient temperature while also driving rotational airflow throughout the space, which in turn promotes particle evaporation. The accompanying animation further reveals that larger-diameter particles tend to settle at lower positions than smaller particles, owing to their greater mass, before eventually evaporating — offering a clear picture of how fragrance particles disperse, settle, and evaporate throughout the restroom under the combined influence of airflow and heating.