Numerical simulation of airflow movement in human mouth-throat model during cyclic respiratory pattern

The method of CFD was used to study airflow movementcharacteristics in human mouth-throat model. We investigated the airflowpatterns in human mouth-throat model, and the effect of airflow movement onthe wall of the mouth-throat model and the aerosols deposition werediscussed. During the inhalation phase, the airflow separates gradually nearthe outer wall of the pharynx and near the outer wall for the upper part ofthe trachea downstream of the glottis with, and the features of theseparation zone appearing is gradually formed. During the exhalation phase,the high velocity zone is created near the outer wall of pharynx and nearthe outer wall of the larynx. During the cyclic respiratory pattern, thehigh axial velocity zone and secondary flow are generated intermittently,eventually to induce the intermittent appearance of the high shearingstrength stress zone appears intermittently. The direction of the shearstress acting on the wall vary varies periodically, which not onlyresult in the increase of the probability of the wall strain and tissueinjury, but also lead to aerosol deposition easily in these areas at thesame time.