The number of typhoons making landfall in Japan has been increasing due to global warming, and there are concerns that the number of “supertyphoons”*¹ will increase in the future.
Therefore, in the design of buildings, the effects of typhoons must be considered with greater accuracy than ever before. However, predicting “ever-changing winds,” such as during typhoons, through conventional technology has been a challenge that requires a considerable amount of time and money.

The numerical wind tunnel “Kazamidori” is a numerical simulation technology that can predict ever-changing winds with high accuracy. It eliminates the aforementioned issues of time and money, and makes it easier to apply to small- and medium-sized projects.

• *1 Supertyphoon: Translation of the Japanese term for the maximum intensity class typhoon (130 kts (≈66.9 m/s) or higher) as classified by the Joint Typhoon Warning Center of the United States

Conventional simulation techniques and their challenges

"Wind load," which refers to the wind force a building is subjected to, needs to be evaluated to build a typhoon-resistant building. For example, it affects the area and thickness of window glass, exterior materials, and the shape of a building.

Numerical simulation (by steady-state analysis)

Numerical simulation techniques widely used in building wind evaluation and indoor airflow prediction are unfortunately not applicable to the evaluation of wind load. This is because such technology evaluates the “average wind.” For wind load evaluation, however, ever-changing winds, particularly the strongest wind (wind pressure), needs to be evaluated.

Wind tunnel experiments

Wind tunnel experiments are widely used for wind load evaluation today. This involves building a model and applying wind to it to measure wind pressure.
While it is possible to make highly accurate predictions, creating these models requires a considerable amount of time and money. Therefore, it is difficult to apply this method to small- and medium-sized projects.

Features of Kazamidori

Kazamidori is a “numerical wind tunnel” that combines the best of numerical simulation and wind tunnel testing.

“Wind tunnel experiments” that do not need models

An urban area is reproduced on a computer, and the wind load on a building is calculated using a numerical simulation. It recreates ever-changing winds and visualizes the strength and flow of the wind. This reduces the costs involved in modeling, making it easier to apply this method to small- and medium-sized projects. The time required for research is also reduced, and wind load evaluation can be incorporated from the early design stage.

Recreation of past typhoons and hypotheses about future supertyphoons

It is possible to reproduce specific typhoons by linking meteorological data. In addition to recreating past typhoons, such as Typhoon X of Year Y, the system can assume the impact of supertyphoons, which are expected to increase in the future. This then enables us to verify the risk of typhoon damage and predict the impact.

　　

Responding to wind problems

In addition to wind load, the “residential performance against wind swaying,” “presence or absence of unstable vibrations,” and “maximum wind speed around a building” can be assessed. The swaying of a building during high winds can be reduced by 25 percent through changing the shape of a building.

Even buildings with complex shapes can be evaluated.

Detailed and complex shapes are a challenge in wind tunnel testing, which requires models. Kazamidori allows the assessment of every detail.