Newsletter  2022.11  Index

Theme : "20th The Dream of Flow Contest” Preface Byungjin AN, and Masaaki MOTOZAWA Report on the 20th Dreams of Flow Contest Motohiko NOHMI (Ebara Corporation) Investigation into efficient ventilating methods Yoichiro TAMADA, Shota YOSHIDA, Naoya OHBA, and Kohei KUYAMA (Waseda University) Amazing Liquid Metal Crown Ryuto ONOZUKA, Ryunosuke NISHIO, Kenshi OHNO, Ken HAYASHIDA, Ryuhei MUTO, and Toranosuke HORIKAWA (Tokyo Institute of Technology) The Dream of Flow Contest Retrospective Shunya UDA, and Yoshiharu KANETA (Nihon University) Demonstration of Portable electrical tomography system and its application  So SEGAWA (Chiba University)

 

Investigation into efficient ventilating methods

Yoichiro TAMADA, Shota YOSHIDA, Naoya OHBA, and Kohei KUYAMA (Waseda University)

Abstract

The team named “Shinsen-kuuki” (which means “flesh  air”) got  the  first  prize at the 20^th Nagareno yume (which means “Dreams of Flow”) Competition held on 7^th August 2022. In this paper, allow us to share the team’s research and its background, showing the results, which the author do hope helps you have the better idea to ventilation of a room, and the remnants, which the team could not have done. The focus was put onto the ventilation, whose popularity has possibly skyrocketed just after the outbreak of covid-19 which took place earlier 2020. The focus seemed perfect at the kickoff, because the main theme of the competition was “Let’s discuss on the Safe, Peaceful and Reliable Flow”. The research was done in order to find out the best way to ventilate the air in the room, measuring the CO2 concentration (CO2 ppm) and using computer fluid dynamics (CFD). The air with vortex which does not exchange itself with outside was regarded as “not ventilated well”, and vice versa. Under variable situations, the CO2 ppm of a room where Miyagawa laboratory students study, and the flow vector in the CFD were recorded. The results indicated four facts; one is that CO2 ppm shows the level of ventilation of specific area, another is that opening windows or doors always helps ventilation. Another is that bulk objects such as whiteboards should be removed for smother air flow, and the other is that the more vortex in the room exists, the higher CO2 ppm of the room will be. Through the results, the room’s ventilation was improved, making students relieved for feeling safer than before. What is even more, it was found putting a circulator near the door or window drastically helped the ventilation go smoother, because less vortex will be created in this way. The result will be even more reliable with CFD which tracks each particle of breath, so that it will be clearer how the virus travel from a patient to another person.

Key words

Analytical wall function, RANS, LES, Engineering CFD

Figures

Fig 1. The room’s 3D model

Fig 2. The room with whiteboard(left) and without(right)---after removing it, the CO2 ppm decreased from 585ppm to 417ppm, with less vortex left in the room

Fig 3. An example case where circulators are not fully utilized --circulators are causing flows which does not get out the room

Fig 4. An example case where circulators put just near the windows/doors –accelerated exiting flow playing a big role aiding the ventilation