Construction of a physical model of airflow, droplets, and droplet nuclei ejected by human respiratory activity

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K18763
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 23:Architecture, building engineering, and related fields
• Research Institution: The University of Tokyo
• Principal Investigator: Ooka RYOZO 東京大学, 生産技術研究所, 教授 (90251470)
• Co-Investigator(Kenkyū-buntansha): 菊本 英紀 東京大学, 生産技術研究所, 准教授 (80708082) ; 呉 元錫 東京大学, 生産技術研究所, 助教 (10889009)
• Project Period (FY): 2021-07-09 – 2023-03-31
• Keywords: 飛沫 / 飛沫核 / CFD / PIV / IMI

Outline of Final Research Achievements

The purpose of this study is to clearly grasp the physical phenomenon that droplets and droplet nuclei ejected by human respiratory activities (coughing, sneezing, talking) scatter and diffuse into the indoor environment by measurement, and develop numerical analysis method (CFD). intended to reproduce. Human respiratory activity generates a mixed flow of airflow and droplets/droplet nuclei . Particle image velocimetry (PIV) and interferometric imaging (IMI) techniques need to be realized to accurately measure the particle size distribution of airflow and droplets/droplet nuclei. In this study, we performed airflow and particle measurements in various respiratory activities using PIV and IMI techniques under unsteady airflow conditions. These results were used as boundary conditions and validation data for CFD. In addition, we modeled the droplet evaporation phenomenon. The constructed CFD model was cross-validated by a visualization experiment of human respiratory activity.

Free Research Field

建築環境工学

Academic Significance and Societal Importance of the Research Achievements

室内環境では、換気システムを効率的に運用することで、空気中に広がって浮遊する飛沫・飛沫核の濃度を減らし空気感染のリスクを抑えることができる。換気システムにおける感染リスクの評価や感染経路の予測には、CFD解析が有効である。今回の研究では、室内環境における飛沫・飛沫核の動態を予測するCFD解析手法を開発することができた。本研究の成果は、今後、室内環境における感染拡大予防の対策に貢献すると期待される。