In the setting of widespread severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) community transmission, reducing the exposure risk on dental professionals and the next patients is the key to reopening dental services in this pandemic environment. The study is motivated by the lack of understanding of the flow-field characteristics and droplet distribution during aerosol-generating procedures. The particle image velocimetry measurements with high temporal and spatial resolutions were performed under ultrasonic scaling in the mockup experimental dental clinic. Compared with other methods focusing on the settled droplet particles, the study focused on the visualization of suspended droplets. From the results of the velocity vector and trajectory map, the high-level contaminated area will be within 1 m from the oral cavity. The vortex structures were identified by the vorticity index. In the surface near the patient's head, a counterclockwise vortex would carry some droplets and contaminate this region. The small droplets circulated in the turbulence cloud and the droplet nuclei generated by dehydration are the two primary sources of suspended particles, which may cause airborne transmission in the dental clinic. About 65%-74% of the droplets in ultrasonic scaling were in the range of 50-180 μ m . The research will provide references to the development of the precaution measures to reduce the SARS-CoV-2 exposure risk of dental professionals.

中文翻译：

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在COVID-19大流行期间，在样机牙科诊所评估流场和排出的飞沫。

在广泛的严重急性呼吸系统综合症冠状病毒2（SARS-CoV-2）社区传播的情况下，降低在牙科专家和下一位患者身上的暴露风险是在这种大流行环境下重新开放牙科服务的关键。这项研究是由于对气雾生成过程中流场特性和液滴分布的了解不足而引起的。具有高时间和空间分辨率的粒子图像测速仪测量是在样机实验牙科诊所中在超声缩放下进行的。与其他关注沉降液滴粒子的方法相比，本研究着重于悬浮液滴的可视化。根据速度矢量和轨迹图的结果，高污染区域将在距口腔1 m的范围内。涡旋结构由涡度指数确定。在患者头部附近的表面，逆时针涡旋将携带一些液滴并污染该区域。在湍流云中循环的小液滴和由脱水产生的液滴核是悬浮颗粒的两个主要来源，它们可能导致牙科诊所中的空气传播。在超声定标中，约65％-74％的液滴在50-180μm的范围内。该研究将为预防措施的开发提供参考，以减少牙科专业人员的SARS-CoV-2暴露风险。在湍流云中循环的小液滴和由脱水产生的液滴核是悬浮颗粒的两个主要来源，它们可能导致牙科诊所中的空气传播。在超声定标中，约65％-74％的液滴在50-180μm的范围内。该研究将为预防措施的开发提供参考，以减少牙科专业人员的SARS-CoV-2暴露风险。在湍流云中循环的小液滴和由脱水产生的液滴核是悬浮颗粒的两个主要来源，它们可能导致牙科诊所中的空气传播。在超声定标中，约65％-74％的液滴在50-180μm的范围内。该研究将为预防措施的开发提供参考，以减少牙科专业人员的SARS-CoV-2暴露风险。