Characteristics Of Natural Wind Research Articles

Researches on wind effects on domes in Brazil

Informations about experimental studies of wind effects on domes conducted at the Federal University of Rio Grande do Sul (UFRGS), Brazil, are given. The tests showed the importance of simulation of the main characteristics of natural wind as well as the influence of size and position of openings. A ventilator was always favorable to the stability of the dome against lift.

高層建築物の外装材を対象とした風力に関する研究(その1) : 平均室内圧の性状について

The characteristics of wind-induced internal pressures in a high-rise building have been investigated. Full-scale measurements were taken using absolute pressure meters, which allowed high-resolution measurements. This paper outlines full-scale measurements of wind velocity, wind direction and external and internal pressures on a twenty-nine-story building, commencing in January 1993. It also describes the characteristics of natural wind above the building's penthouse and mean wind-induced internal pressures measured in September 1995 when Typhoon No.12 hit the Kanto area. The internal pressure coefficients obtained from these measurements were about -0.26, and were constant over the building's height. The influence of internal walls and doors on measured mean internal pressure coefficients was found to be insignificant, and roughly the same values were obtained at different locations on the same floor. The mean internal pressure coefficient estimated from the mean wind pressure coefficient obtained from wind tunnel testing was -0.26, which was the same as that obtained from the full-scale measurement. Therefore, it is inferred that the mean wind pressure coefficient obtained from the wind tunnel testing is sufficient for examining average internal pressures.

Physical-modeling investigations for wind engineering: Applications beyond wind-load determinations

Physical modeling (PM) has a long history of development and use for studies of hydraulic, aeronautical, mechanical, and chemical engineering problems with complex fluid flow and boundary conditions. Applications of PM to wind engineering (WE) were delayed until the ability to model flow characteristics of natural wind was realized by development of boundary-layer wind tunnels (BLWT's) in the 1960's. Following development of BLWT's, PM of wind loads on building and structures became the primary source of wind-load data. This aspect of PM is only summarized herein and emphasis is given to three relatively new applications of PM to WE: 1) determination of local wind characteristics, 2) quantification of atmospheric transport of mass and heat, and 3) transmission of sound and light. These classes of PM applications are described by reference to specific examples.

Advances in Physical Modeling for Wind Engineering

Physical modeling to quantify wind effects for either wind‐engineering design or research requires simultaneous similarity for two distinct physical phenomena. The initial consideration is similarity of the desired natural wind characteristics. When this requirement is satisfied, similarity of specific wind effects must then be considered. Advancements in both aspects of simulation since about 1974 are summarized following a brief review of the foundations of physical modeling and wind‐modeling facilities. Advancements in physical modeling of the following natural wind features are described: (1) Elevated inversions; (2) wind‐water interactions; (3) mountain‐valley winds; and (4) large‐scale atmospheric turbulence. Extensions in the capability to simulate and measure the following wind effects are presented: (1) Diffusion in convective boundary layers; (2) heat transfer by heated jet in wind; and (3) fluctuating wind loads on buildings and structures. Advancements in physical modeling during the last decade have significantly increased the scope of wind‐engineering problems that can be treated quantitatively. However, further advancements are needed. Some challenges for future research and development are identified.

Wind‐Simulation Criteria for Wind‐Effect Tests

Pressures, loads, dynamic responses and adverse pedestrian‐level environments caused by wind action on buildings and structures are commonly determined by physical modeling in wind tunnels. Accurate quantitative evaluation of these effects for wind engineering requires that natural wind characteristics be simulated with reasonable fidelity. Features of boundary‐layer wind tunnels that meet this requirement are presented and reviewed. Two general criteria are proposed as minimum performance requirements of wind tunnels used to test buildings and structures for wind effects.

The use of cross-jets to simulate wind characteristics

The wind-tunnel simulation of natural wind characteristics is usually done with solid obstacles placed at the entrance of the working section and/or distributed on the floor. The approach presented in this paper uses an aerodynamic technique to achieve that purpose: a row of air jets directed perpendicularly to the longitudinal wind-tunnel stream. Some results agree reasonably well with natural wind measurements of mean wind velocity profile, intensity, scale, and power spectrum of longitudinal turbulence. The main advantages of the approach presented are: (i) the wind characteristics are controlled, in a rather wide range, by just opening or closing a valve; (ii) the artificially thickened boundary layer is obtained without solid obstacles and their blockage effects; there is no loss in flow velocity.

Characteristics of natural wind - Pt. I: Mean flow

The aerodynamic friction offered by various objects on the earth and the earth itself to the movement of air creates wind forces on structures. These wind forces have become more and more critical due to the more slender and unusual design of present day structures. The available data on mean wind speed measurement in the lower part of the atmospheric boundary layer, as relevant to wind loading on structures, are analysed critically and correlated analytically. It is concluded that under certain conditions the variation of mean wind speed with height ill neutral stability can be satisfactorily represent6d by a simple power law. The index of the power law and the corresponding gradi6llt height must, however, be varied to take account of the roughness of the surface. Further the total change in mean wind direction over a few hundred feet being a few degrees, may be neglected during considerations of most structures. Finally suggestions are made for the power law exponent, gradient height and the surface drag coefficient for the four typical categories of terrain. The suggested values are confirmed by recent measurements of wind speed made in various parts of the world.

Studies on the wind in front and back of the shelter-hedges (1)

Some characteristics of natural wind have been investigated in front and back of plain shelter-hedges, 80cm high and 15m long, of several kinds of type having interstice of 80% (type A), 50% (B), 20%(C) and 0% (D) respectively. Being inspected the horizontal distributions of wind velocity at the height of 50cm, it has been made clear that there exist the zone of acceleration just behind the hedges of tybe A and B and the zone of deceleration for C and D, which are considered to be due to the local blowing and the interruption of wind respectively.The vertical distribution of wind velocity for the hedge A has been shown to keep almost the logarithmic law except at the station extremely near the hedge, and, on the other hand, those for B, C and D have been shown to increase discrepancy from the logarithmic law at heights below 1m as the degree of interstice decreases.The degree of wind wind velocity turbulence increased just behind the hedges has tended to decrease with the distance from hedges, and it has been shown that at the distance of 20 times of hedge height the influence of hedge has either disappeared for A and B or remained for C and D.