A computational fluid dynamics model for the simulation of flashboiling flow inside pressurized metered dose inhalers

TL;DR

This paper introduces a novel computational fluid dynamics model for simulating flashboiling flow in pressurized metered dose inhalers, enabling better understanding and optimization of inhaler design.

Contribution

The first CFD tool for simulating metered discharge in inhalers using open-source software with cavitation and multiphase flow modeling.

Findings

Model accurately predicts flow dynamics and thermodynamics.

Validated against experimental visualizations and measurements.

Enables systematic inhaler design optimization.

Abstract

In this work we present, for the first time, a computational fluid dynamics tool for the simulation of the metered discharge in a pressurized metered dose inhaler. The model, based on open-source software, adopts the Volume-Of-Fluid method for the representation of the multiphase flow inside the device and a cavitation model to explicitly account for the onset of flashboiling upon actuation. Experimental visualizations of the flow inside the device and measurements of the mixture density and liquid and vapor flow rates at the nozzle orifice are employed to validate the model and assess the sensitivity of numerical results to modeling parameters. The results obtained for a standard device geometry show that the model is able to quantitatively predict several aspects of the dynamics and thermodynamics of the metered discharge. We conclude by showing how, by allowing to reproduce and understand the fluid dynamics upstream of the atomizing nozzle, our computational tool enables systematic design and optimization of the actuator geometry.