  Airflow through the nasal cavity exhibits a wide variety of fluid
dynamicsbehaviour due to the intricacy of the nasal geometry. The flow is
naturallyunsteady and perhaps turbulent, despite CFD in the literature that
assumesa steady laminar flow. Time-dependent simulations can be used to
generatedetailed data with the potential to uncover new flow behaviour,
although theyare more computationally intensive compared with steady-state
simulations. Furthermore, verification of CFD results has relied on reported
pressure drop(e.g. nasal resistance) across the nasal airway although the
geometries usedare different. This study investigated the unsteady nature of
inhalation atflow rates of 10, 15, 20, and 30 L/min. A scale resolving CFD
simulationusing a hybrid RANS-LES model was used and compared with
experimentalmeasurements of the pressure distribution and the overall pressure
drop in thenasal cavity. The experimental results indicated a large pressure
drop acrossthe nasal valve, as well as across the nasopharynx with the latter
attributedto a narrow cross-sectional area. At a flowrate of 30 L/min, the CFD
simula-tions showed that the anterior half of the nasal cavity displayed
dominantlylaminar but disturbed flow behaviour in the form of velocity
fluctuations. Theposterior half of the nasal cavity displayed turbulent
activity, characterised byerratic fluctuating velocities, which was enhanced by
the wider cross-sectionalareas in the coronal plane. At 15L/min, the flow field
was laminar dominantwith very little disturbance confirming a steady-state
laminar flow assumptionis viable at this flow rate.
