turbulence

Using meteorological and physical data, a model simulating pressure and air mass flow distribution in buildings was produced using the method of non-linear networks. It was used to study wind and buoyancy effects on mechanically ventilated buildings. Contents include: natural ventilation in high rise buildings with and without air-handling equipment, a study of a hospital, and calculation of the annual heat load for ventilation.

Using meteorological and physical data, a model simulating pressure and air mass flow distribution in buildings was produced using the method of non-linear networks. It was used to study wind and buoyancy effects on mechanically ventilated buildings. Calculations were made for a naturally ventilated high rise building for varying permeability distributions and air flow resistances of the building envelope, using data from real buildings and from previous cases described in the literature.

Reports on experiments carried out on models with trough roofs in order to study the influence of parapet height and wind turbulence. The models were exposed to both turbulent shear flow and a smooth uniform flow. Pressure coefficients were c

Describes results from wind-tunnel tests on models of the Building Research Establishment's experimental building at Aylesbury. The use of several scale models of this building in uniform and in simulated atmospheric boundary-layer flows together with the results from the full-scale experiments allow an assessment of the effect of variations in the ratio of the longitudinal- turbulence integral length scale to body dimension.

Considers the characteristics of flow through small gaps. Discusses relation between wind tunnel measurements and actual wind pressure on buildings and the effect of building shape on ventilation. Derives equations for flow rate through a gap for different temperature and pressure differences and sizes of gap. The equations consider the pressure as a function of time thus modelling the effects of a turbulent wind incident on a gap.

Investigates use of an array of spires, located at the entrance to the working section of a conventional wind tunnel, as a means of generating thick shear layers with properties similar to those of the neutrally-stable atmospheric wind. Compares data obtained in the shear layers created by sucharrays of spires with some available atmospheric data. Modifications to thespire design and a range of spire sizes have been tested and the resulting shear layer properties compared.

Discusses the physical nature of atmospheric boundary layer flows. Concludes that the primary aims in the simulation of these flows in a wind tunnel should b to model the relevant scales and intensities of turbulence. Simulation of the variation of mean wind velocity with height is also desirable. Proposes a system of barriers and vortex generators as a means of simulating turbulent and neutral atmospheric boundary layers.Discusses the characteristics of induced turbulent flow. Finds that the developed flow is a good approximation to the natural boundary layer.

Reports an investigation of wind loading with emphasis on the local pressure fluctuations, on a small scale building model in a thick turbulent boundary layer wind tunnel. A striking similarity between the oncoming turbulent energy spectra andsurface pressure-fluctuation spectra was consistently observed. This similar behaviour suggests that the upstream turbulence plays a dominant role in producing the pressure fluctuations on the upwind face of a bluff body.

Reports experiments carried out in a wind tunnel on two kinds of two-dimensional roughness arrays and on one array of three-dimensional roughness with a turbulent boundary layer growing over the arrays. Drag coefficient on an individual element was measured by pressure tapping as its height was varied relative to the average height of the array. Some general forms for the drag coefficients are found for the two-dimensional case. Results for the three dimensional case show some general trends but more work is needed.

Reports measurements of wind pressure distributions on the surface of a rectangular cylinder model in a wind tunnel. Finds fluctuating character of pressure on roof surface is dependent on the turbulent structure of wind tunnel flow. Experiments were also made on box-shaped models with square section. Finds windpressure distribution on the roof became uniform with increasing height of the model. Gives diagrams of wind pressure coefficients.