Keyhani K, Scherer P W, Mozell M M
Department of Bioengineering, University of Pennsylvania Philadelphia 19104-6392, USA.
J Biomech Eng. 1995 Nov;117(4):429-41. doi: 10.1115/1.2794204.
An anatomically correct finite element mesh of the right human nasal cavity was constructed from CAT scans of a healthy adult nose. The steady-state Navier-Stokes and continuity equations were solved numerically to determine the laminar airflow patterns in the nasal cavity at quiet breathing flow rates. In the main nasal passages, the highest inspiratory air speed occurred along the nasal floor (below the inferior turbinate), and a second lower peak occurred in the middle of the airway (between the inferior and middle turbinates and the septum). Nearly 30 percent of the inspired volumetric flow passed below the inferior turbinate and about 10 percent passed through the olfactory airway. Secondary flows were induced by curvature and rapid changes in cross-sectional area of the airways, but the secondary velocities were small in comparison with the axial velocity through most of the main nasal passages. The flow patterns changed very little as total half-nasal flow rate varied between resting breathing rates of 125 m/s and 200 ml/s. During expiration, the peaks in velocity were smaller than inspiration, and the flow was more uniform in the turbinate region. Inspiratory streamline patterns in the model were determined by introducing neutrally buoyant point particles at various locations on the external naris plane, and tracking their path based on the computed flow field. Only the stream from the ventral tip of the naris reached the olfactory airway. The numerically computed velocity field was compared with the experimentally measured velocity field in a large scale (20x) physical model, which was built by scaling up from the same CAT scans. The numerical results showed good agreement with the experimental measurements at different locations in the airways, and confirmed that at resting breathing flow rates, airflow through the nasal cavity is laminar.
利用一位健康成年男性鼻子的CAT扫描数据构建了一个解剖学上正确的右鼻腔有限元模型。通过数值求解稳态Navier-Stokes方程和连续性方程，确定安静呼吸流速下鼻腔内的层流气流模式。在主要鼻道中，吸气时最高气流速度出现在鼻底（下鼻甲下方），第二个较低峰值出现在气道中部（下鼻甲与中鼻甲和鼻中隔之间）。近30%的吸入体积流量从下鼻甲下方通过，约10%的流量通过嗅觉气道。气道曲率和横截面积的快速变化会引发二次流，但与大部分主要鼻道中的轴向速度相比，二次流速度较小。当半鼻腔总流速在静息呼吸速率125ml/s至200ml/s之间变化时，气流模式变化很小。呼气时，速度峰值小于吸气时，且鼻甲区域的气流更均匀。通过在鼻孔平面的不同位置引入中性浮力点粒子，并根据计算出的流场跟踪其路径，确定了模型中的吸气流线模式。只有来自鼻孔腹侧尖端的气流能到达嗅觉气道。将数值计算得到的速度场与通过相同CAT扫描数据按比例放大构建的大型（20倍）物理模型中实验测量的速度场进行了比较。数值结果与气道不同位置的实验测量结果吻合良好，证实了在静息呼吸流速下，鼻腔内的气流是层流。
