Ear, Nose, and Throat (ENT) Department, University Hospital of Bordeaux, Hôpital Pellegrin, Bordeaux, France.
Centre d'Investigation Clinique et d'Innovation Technologique de Bordeaux (CIC-IT 14-01), University Hospital of Bordeaux, France.
Int Forum Allergy Rhinol. 2018 Jun;8(6):676-685. doi: 10.1002/alr.22086. Epub 2018 Jan 16.
Computational fluid dynamic (CFD) simulations have greatly improved the understanding of nasal physiology. We postulate that simulating the entire and repeated respiratory nasal cycles, within the whole sinonasal cavities, is mandatory to gather more accurate observations and better understand airflow patterns.
A 3-dimensional (3D) sinonasal model was constructed from a healthy adult computed tomography (CT) scan which discretized in 6.6 million cells (mean volume, 0.008 mm ). CFD simulations were performed with ANSYS©FluentTMv16.0.0 software with transient and turbulent airflow (k-ω model). Two respiratory cycles (8 seconds) were simulated to assess pressure, velocity, wall shear stress, and particle residence time.
The pressure gradients within the sinus cavities varied according to their place of connection to the main passage. Alternations in pressure gradients induced a slight pumping phenomenon close to the ostia but no movement of air was observed within the sinus cavities. Strong movements were observed within the inferior meatus during expiration contrary to the inspiration, as in the olfactory cleft at the same time. Particle residence time was longer during expiration than inspiration due to nasal valve resistance, as if the expiratory phase was preparing the next inspiratory phase. Throughout expiration, some particles remained in contact with the lower turbinates. The posterior part of the olfactory cleft was gradually filled with particles that did not leave the nose at the next respiratory cycle. This pattern increased as the respiratory cycle was repeated.
CFD is more efficient and reliable when the entire respiratory cycle is simulated and repeated to avoid losing information.
计算流体动力学（CFD）模拟极大地提高了对鼻腔生理学的理解。我们假设，模拟整个和重复的呼吸鼻腔周期，在整个鼻旁窦腔内，是强制性的，以收集更准确的观察和更好地了解气流模式。
从健康成人的计算机断层扫描（CT）扫描构建了一个三维（3D）鼻旁窦模型，该模型离散化了 660 万个细胞（平均体积为 0.008 毫米）。使用 ANSYS©FluentTMv16.0.0 软件进行了 CFD 模拟，具有瞬态和湍流气流（k-ω 模型）。模拟了两个呼吸周期（8 秒），以评估压力、速度、壁面剪切应力和颗粒停留时间。
窦腔内的压力梯度根据其与主通道的连接位置而变化。压力梯度的变化在接近口处引起了轻微的泵送现象，但在窦腔内没有观察到空气的运动。在呼气时，在下鼻甲内观察到强烈的运动，与吸气时相反，同时在嗅裂处也是如此。由于鼻阀阻力，颗粒在呼气时的停留时间比吸气时长，就好像呼气阶段正在为下一个吸气阶段做准备。在整个呼气过程中，一些颗粒仍然与下鼻甲接触。下鼻甲的后部分逐渐充满了在下一个呼吸周期内不会离开鼻子的颗粒。这种模式随着呼吸周期的重复而增加。
当整个呼吸周期被模拟和重复时，CFD 更有效和可靠，以避免丢失信息。
