On the assumption of steadiness of nasal cavity flow

The unsteady flow through a model of the human nasal cavity is analyzed at a Strouhal number of Sr=0.791Sr=0.791 for the complete respiration cycle. A comparison of the essential flow structures in the model geometry and a real nasal cavity shows the relevance of the model data. The analysis of the steady and unsteady solutions indicate that at Reynolds numbers Re≥1500Re≥1500 the differences of the solutions of the unsteady and steady flow field can be neglegted. To be more precise, the comparison of the total pressure loss distribution as a function of mass flux for the steady state and unsteady solutions shows the major differences to occur at increasing mass flux. At transition from inspiration to expiration the unsteady results differ the most from the steady state solutions. At high mass fluxes the total pressure loss of the nasal cavity flow almost matches that of the steady state solutions. The comparison with rhinomanometry measurements confirms the present numerical findings.