CFD Analysis of Asthma Spray Delivery in Human Lungs

This study presents a computational fluid dynamics simulation examining the delivery and distribution of asthma medication spray within a simplified human lung model using ANSYS Fluent software.

Model Development

A three-dimensional lung model was created using SpaceClaim software, featuring a simplified representation of human pulmonary airways with an inlet diameter of 50cm. The computational mesh was generated using ANSYS Meshing software with 3,734,238 elements to ensure accurate resolution of both airflow patterns and particle trajectories throughout the complex airway geometry.

Given the time-dependent nature of inhaler spray delivery and particle transport, a transient solver approach was implemented.

Simulation Methodology

The one-way Discrete Phase Model (DPM) was employed to track medication particles within the continuous airflow medium. Key simulation parameters included:

• Continuous phase: Air
• Discrete phase: Medication particles
• Air inlet velocity: 5 m/s
• Gravitational acceleration: -9.81 m/s² (along z-axis)
• Particle diameter: 100 microns
• Injection method: Surface velocity injection
• Turbulence model: Realizable k-epsilon

The one-way coupling approach was selected as appropriate for this application, as the relatively low concentration of medication particles would have minimal impact on the overall airflow patterns, while the airflow significantly influences particle transport.

Results and Analysis

The simulation produced comprehensive visualization outputs including:

• Two-dimensional velocity contours
• Three-dimensional velocity fields
• Pressure distribution throughout the airways
• Particle tracking animations showing medication transport

The results demonstrated how the airflow patterns within the bronchial tree significantly influence the distribution and deposition of medication particles. Areas of flow recirculation, velocity gradients, and geometric features (such as bifurcations) were shown to affect particle trajectories and potential deposition sites.

This analysis provides valuable insights for pulmonary drug delivery optimization, potentially informing the design of inhalation devices and delivery protocols to maximize therapeutic efficacy for asthma patients by ensuring medication reaches intended target regions within the lungs.