An analytical model has been developed for calculating the velocity field in a moving typhoon boundary layer. The present model has an upper inviscid region of cyclostrophic balance and a lower friction region controlled by surface drag coefficient and eddy viscosity. The velocity in the inviscid region is first described using an assumption that wind field moves with translation velocity of typhoon. A perturbation analysis is then perfonned to obtain the tangential and radial boundary layer velocity in the friction region. Validation of the model is carried out by comparing observed wind speed and direction records obtained from three typhoons in 1991 to those predicted by the model itself. The wind velocity and direction predicted are in good agreement with those observed at a one-hundred metre tall tower. Rapid variation of the wind velocity depends on the surface roughness and topograpy around the tower. Finally, a case study is conducted to examine the characteristis of the ratio of surface to gradient wind speeds G (r) and the inflow angle γ in the typhoon boundary. Previous typhoon observations data in coastal regions are well explained by this model.
It is important to know the configuration of the surface roughness, because the wind characteristics in the atmospheric boundary layer near the ground are mainly affected by the surface roughness. Configurations of houses and buildings in real urban cities were obtained from maps and aerial photographs. The relation of the number, the scale and the volume of houses and buildings against the number of stories were evaluated from these data. Using these results, various parameters of roughness configurations against the roughness volume density are examined for real urban areas.
Wind tunnel Research Facilities with two test sections have been built for civil engineering structures and aviation applications. The test section for applications in civil engineering structures is a closed-type and has the dimension of 2.5m in height, 2.0m in width, and 15.Om in length. At the test section, wind velocities from 0.2m/s to 50m/s can be used. The wind velocity uniformity distribution is within ±0.6 %, turbulence intensities are less than 0.3 %, and static pressure distribution is less than 0.2 %/m. The test section for aviation applications is an open-type with the dimension of 2.5m × 2.5m × 5.0m. Wind velocities from 0.2m/s to 45m/s are available for this section and the uniformity of the wind velocity is within ± 1.0 %, and turbulence intensities are less than 0.3 %. The characteristics and performance of the Wind Tunnel Facilities are presented in this paper.