CFD Analysis of Transport Process of Virus Concentration in an Airway with Consideration of Adhesion

An airway is likely to be contacted with virus. When the virus is adhered to the airway by breath, some humans maybe get infected. Therefore, the infection risk is important to predict by evaluating quantitatively the adhesion area and the amount of virus. The airway consists of the nasal cavity (such as the maxillary sinus, ethmoid sinus, frontal sinus, and sphenoidal sinus), pharynx, larynx, trachea, bronchi, and lungs. In this study, CFD analysis of transport process of virus concentration in the airway was conducted by considering adhesion and breathing waveform, and the infection risk at sinuses were predicted. The 3D geometry of the nasal cavity can be constructed from 2D-CT (Computed Tomography) image data utilizing ITK-SNAP. The flow within the nasal cavity is assumed to an incompressible, unsteady (pulsatile flow), and turbulent. The continuity equation and the Navier-Stokes equations are used in computational fluid dynamics (CFD) analysis. In CFD analysis, the boundary condition at the inlet is defined that the pressure is zero, and the concentration is dependent on inlet mass flow. The boundary condition at outlet is defined that the velocity is the simulated breathing waveform, and the gradient of concentration is free. The wall boundary condition of concentration is adhesion. It has been determined that the Ethmoid Sinus exhibits a heightened propensity for viral adhesion within the nasal cavity, based on the evaluation of the amount of adhesion. In addition, it was found that the flow is complexed by considering the breathing waveforms. It was found that the concentration diffusion in Maxillary Sinus (Region 1) and Ethmoid Sinus (Region 2) was increased by the generated vortexes. Besides, it was found that the amount of adhesion increases more than twice by considering the adhesion.