modelling

Presents measurements of the mean and fluctuating pressure field acting on two-dimensional square cylinder in uniform and turbulent flows. Shows the addition of turbulence to the flow raises the base pressure and reduces thedrag of the body. Suggests this is attributable to the manner in which increased turbulence intensity thickens the shear layers, which causes them tobe deflected by the downstream corners of the body and results in the downstream movement of the vortex formation region.

The two-storey house at Aylesbury, England, built by the Building Research Establishment for the full-scale measurement of wind pressures has been modelled at 1:500 scale in a boundary layer wind tunnel to verify the reliability of simulation forlow-rise buildings. Describes wind tunnel tests of buildings models of 5 and 22.5 roof slope. Compares surface pressure measurements with full-scale data for various wall and roof locations. For the model terrain best modelling conditions, the results show agreement which is encouraging.

Describes experimental techniques used in the low-speed wind tunnels at the Building Research Station when studying air flow around buildings and pressure distribution over their surfaces. Includes flow visualisation both in the stream and in boundary layers over surfaces, velocity measurements around small-scale models, and methods of building models containing pressure tappings. Gives names of suppliers and details of some instruments and equipments. Describes in an appendix how a simply constructed heated-sphere anemometer is made.

Describes method for simulating natural wind boundary layer in a conventional, short working section, aeronautical wind tunnel. Boundary layers, which may be as thick as one-half of the working section height are generated by spires at the working section inlet. This approach is used to measure mean wind pressures and pressure spectra on a model of a tall building in downtown Montreal. Measurements are repeated using the long roughness fetch technique for boundary layer generation and results from the two methods compared.

Describes typical town centre developments in which a problem of wind environment has arisen, and gives a brief account of the investigation of specific cases. Summarises broad conclusions of 20 special cases. Describes series of investigations intoair-flow around small groups of idealised model buildings and compares model with full-scale measurements. Outlines design method for use in planning layout of small groups of buildings. Discusses future research needs.

Describes the ventilation of buildings by analogy with electric circuits and derives expressions for ventilation with and without flow through ducts in the roof. Finds that in general ventilation rate will vary linearly with wind velocity. Considers the effect of shelter belts on wind velocity and derives expression for sheltered ventilation rate. Suggests that eddy motion caused by shelters may be important. Gives measurements made on models in wind tunnels to show the affect on wind pressure of sheltering buildings at various distances.

Reports wind-tunnel tests on simple cubical model made of plastic to see effect of outside wall leakage on internal and external pressures. Three wind directions are studied and results extended to smoke-control problems. A method has been developed to modify the roof-vent design calculations to takewind effects into account. Shows failure of vent systems may bemore common than would be expected from current design methods.Concludes that leakage characteristics do not have any appreciable effect on outside wind pressures but do affect strongly the internal pressures.

Reports wind tunnel tests made on model building. Wind pressures on the models were measured using several manometers in holes on the windward side and a single manometer on the leeward side atwind speeds of approximately 35 feet and 45 feet per second. Single models and single models with a shielding building at varying distances were tested, and pressure distribution found.Comparison with full-scale tests indicates the general form of pressure distribution is the same but pressure reduction on leeward side is greater in full-scale test.

Describes wind tunnel measurements made on a model of a tall building surrounded by lower buildings under various combination of wind speed, wind angle and air temperature. Gives method for calculation of air infiltration rates and describes the computer program used. Concludes that air infiltration is a strong function of wind direction. Finds that maximum air infiltration was produced by a wind that approached at 0 deg and the minimum air infiltration occurred at 75 deg wind angle.

Treats measurements of ventilation rates in a model building and wind tunnel. 2 types of opening, circular holes and model windows were tested under 2 wind cOnditions. one wind condition was selected to give maximum flow through the model; with theother, ventilation was mainly due to turbulent pressure fluctuations. Illustrates different characteristics of theopenings. Draws comparisons between measurements and theoretical predictions. Discusses use of wind tunnels for ventilation studies. NOTES: A further comment on this paper was published in Building and Environment vol.15 no.141.