turbulence

The growing interest in the response of structures to turbulent wind forces and the realization of the important role played by root-coherence in the prediction of such response has led to the proposal of several expressions for the power

In this paper, the statistical concepts of the stationary time series are used to determine the response of a simple structure to a turbulent, gusty wind. 

The calibration and use of a shielded dual sensor hot-wire probe, originally developed at McGill University for velocity measurement in highly turbulent and reversing flows, is described. The new probe permits measurements to be made in flow conditions which are not amenable to conventional hot-wire techniques. Two conventional hot-wire anemometers are used to drive the probeand a simple electronic circuit is required to decode the signals and producea continuous voltage analogue of the velocity component in one dimension.

This paper discusses the flow of air around ideal (cubic) structures on plane surfaces subjected to a turbulent boundary layer wind. These winds are shown to follow a power-law variation with height, while winds significantly effected by thermal stratification follow a log-linear distribution. Discussion of stagnation zones, flow separation, and pressure changes is included, with possible effects upon air quality and infiltration. Also discussed are variations in building design and addition of neighboring buildings, both which produce very complex winds, yet to be quantized.

Flow patterns at ground level in groups of buildings result from the complex interaction between the wind (impact, average speed distribution with height, and turbulence) and the buildings themselves (shapes, sizes, arrangements, etc.). The

The study, carried out in an atmospheric wind tunnel (reproduction of natural wind conditions, particularly turbulence), quantifies wind flows around built-up obstacles in their realistic location context, and the associated pressure fields. For various types of buildings (detached house, block of flats), the article presents in illustrated form the chart of these flows and pressures in general (mean values, standard deviations, extreme values), but deals more specifically with the wind resistance of solar collectors.

The aerodynamic forces affecting wind and rain penetration of roofs are described. They are: 1 the wind and its turbulent nature, 2 the induced pressure field, 3 the air flows in contact with the roof and 4 the characteristics of the roof (internal pressure, permeability, structure, etc).

Aerodynamic phenomena affecting the ventilation process, such as aerodynamic mixing, generation of secondary and slightly turbulent flows, roof contours, infiltration and convection and their connection with geometric parameters of the object and energy expenditure for ventilation are analysed.

The physical reason for draughts is in the first place the convective surface-heat-transfer coefficient. To find out about the influence of turbulence on draughts, it is necessary to carry out measurements of the surface-heat-transfer coefficient in relation to air turbulence. The results of first measurements of this kind are the subject of this paper.

Plastic track detectors LR-115 and CR-39 were used to estimate the concentration of radon-222 and its daughter products (218Po, 214Po) in a room by recording tracks of their alpha-particles. Although the ventilation rate is the main factor th