A research group led by Tetsuya Takemi, an associate professor at the Disaster Prevention Research Institute of Kyoto University, was targeting Osaka City, and with the passage of Typhoon Jebi in September 2018, how strong a wind was blowing in the actual center of the city. I succeeded in investigating whether or not it was a simulation using a super computer.
Due to the passage of Typhoon No. 21, a maximum instantaneous wind speed of 47.4 meters per second was recorded at the meteorological station in Osaka City.This is the third highest in the history of observation after the Muroto Typhoon and the Second Muroto Typhoon.Great damage occurred in various places in downtown Osaka.In the central area where skyscrapers stand, there is a possibility that a wind stronger than the value observed at the meteorological observatory was blowing momentarily depending on the location, but there was no actual measurement value.
The research group has been developing "Large Eddy Simulation (LES)" technology to calculate complex airflow turbulence.This time, we incorporated the data of actual structures and buildings in the city of Osaka into this LES model, and simulated what kind of wind would blow in the actual city.In addition, in order to grasp the actual weather conditions, we also carry out a separate weather simulation using a computer simulation model for weather forecasts that is used for daily weather forecasts.As a result, it was found that in central Osaka, a storm that momentarily exceeded 60 meters per second and approached 70 meters was blowing in some places.
This time, it has become possible to quantitatively estimate the wind blowing in the urban area under actual weather conditions by combining the weather simulation and the airflow simulation in the urban area.The wind in the city area changes greatly depending on the height of the surrounding buildings and structures.In the future, it will be important to conduct similar simulations in various large cities to understand the risk of storms in the cities.
