Simulation of Aerosol Flow in a Nose-only Inhalation Exposure System Using Ansys Computational Fluid Dynamics (CFD) Software
SEONGGI MIN, Dong-Jin Yang, Jae-Hyun Kim, Gregory Pellar, Jinghai Yi, Susan Chemerynski, Steven Yee, Reema Goel, Pamela Roqué, Prabha Kc, NCTR/FDA
Abstract Number: 148
Working Group: Aerosol Physics
Abstract
Inhalation chambers are widely used for evaluating the toxicity of chemicals in aerosols, including particulate matter. Ensuring consistent and uniform spatial distribution of aerosols within the inhalation chamber is crucial for accurately assessing toxicity. The CTP/NCTR Inhalation Toxicology Core Facility uses a 5-tier (10 ports/tier) nose-only inhalation exposure system in animal studies. Previous studies have investigated the air flow dynamics within the inhalation chamber. However, the impact of the flow on the concentration and distribution of aerosols is not fully understood. In this study, we used the Ansys CFX 17.2 computational fluid dynamics software to simulate the trajectories and distribution of aerosols across all tiers and ports of the inhalation chamber. A cylindrical rod (crown shaped at the top to minimize air resistance) was inserted into the inhalation chamber. A tier without any output ports was added on the top of the 5th tier of the inhalation chamber to help equilibrate the pressure distribution.
Simulation of aerosol flow (75% propylene glycol/25% water) was performed with 25 rods of varying sizes using k-ω shear stress transport turbulence and discrete phase models. The 5 rods with the smallest relative standard deviation of aerosol flow in the simulation were selected for experimental testing. The aerosol spatial distributions were compared from 8 ports across all 5-tiers of the inhalation chamber simultaneously. Aerosols were generated using a collision nebulizer at 25 LPM of air flow. The rod sizes selected were 40x35, 40x40, 40x45, 40x50, and 45x45 mm.
The difference of aerosol flow between the simulation and experimental results ranged between 0.7-10.44% for all the 5 selected rods. Aerosol concentration throughout the study was within 90-110% of the average value. Overall, this work supports the utilization of simulations in the development of homogenous aerosol flow for uniform dosing in animal inhalation exposures.