Importance of the numerical schemes in the CFD of the human nose

TL;DR

This study highlights the critical impact of numerical scheme choices in CFD simulations of the human nose, demonstrating that such decisions significantly influence flow results and emphasizing the need for standardized reporting.

Contribution

It systematically assesses how different discretization schemes affect CFD results in nasal airflow simulations, revealing the importance of numerical scheme selection.

Findings

Choice of numerical scheme greatly affects pressure and velocity results.

Global pressure drop can vary by over 50% based on scheme choice.

All modeling parameters influence the solution, but scheme choice is most critical.

Abstract

Computational fluid dynamics of the air flow in the human nasal cavities, starting from patient-specific Computer Tomography (CT) scans, is an important tool for diagnostics and surgery planning. However, a complete and systematic assessment of the influence of the main modeling assumptions is still lacking. In designing such simulations, choosing the discretization scheme, which is the main subject of the present work, is an often overlooked decision of primary importance. We use a comparison framework to quantify the effects of the major design choices on the results. The reconstructed airways of a healthy, representative adult patient are used to set up a computational study where such effects are systematically measured. It is found that the choice of the numerical scheme is the most important aspect, although all varied parameters impact the solution noticeably. For a physiologically meaningful flow rate, changes of the global pressure drop up to more than 50\% are observed; locally, velocity differences can become extremely significant. Our results call for an improved standard in the description of this type of numerical studies, where way too often the order of accuracy of the numerical scheme is not mentioned.