Optimising Meshing for Computational Fluid Dynamic Analysis of Nasal Airflow: Balancing Efficiency and Mesh Independence

Abstract: Given the intricate and variable anatomical features of the human nasal cavity and paranasal sinuses, optimising meshing strategy and ensuring mesh independence for computational fluid dynamic (CFD) analysis of this geometry is crucial for accurate simulation of airflow and drug delivery. This study addresses limitations of current meshing methods using ANSYS Fluent, which often rely on increasing element count without considering meshing strategy. This can result in inconsistent and computationally inefficient outcomes. Various meshing strategies are evaluated and compared, with specific focus on surface mesh sizing, boundary layer generation, and volume mesh settings. The performance of each meshing strategy is assessed based on the consistency of velocity contours, nasal resistance calculations, near-wall velocity gradients and overall computational efficiency. Results indicate that use of body sizing with a growth ratio of 1.2 and a boundary layer with 8 uniform prism layers yields the most reliable and computationally efficient outcomes out of the investigated meshes. Meshes using this strategy exhibit asymptotic behaviour above 3.7 million elements. These findings provide a framework for future CFD studies aiming to verify mesh independence for similar anatomical geometries and provide several recommendations for verifying mesh independence for laminar airflow in airways. Keywords: Mesh independence test, Computational Fluid Dynamics, Nasal cavity, Computed tomography reconstructed geometry, Meshing strategy, Chronic Rhinosinusitis, Drug delivery