J.A. Wisse

Accuracy of assessment of wind speed in the built environment

Wind tunnel simulations and criteria for wind comfort and safety are used to assess the wind climate in the built environment. Probability of occurrence of a critical wind speed is derived from as well wind tunnel results as data from a meteorological station. The paper discusses sources of error in the various steps. It is shown that at least a 20% standard deviation in the estimate of local wind speeds has to be accounted for. This error has impact on the application of various comfort criteria.

Towards forecasting of wind comfort

Abstract Numerical results of a K-ϵ model are compared with LDA measurements. Hot wire results are shown to be unsuitable if turbulence intensity (TI) is over 45%. Numerical results for isolated buildings are within 10–20% of experiments, provided that the K-ϵ model constant C μ is matched to the approach flow value. For skimming flow over an obstacle group, the standard C μ is appropriate. A parametrization of turbulence intensity as a function of local wind amplification factor has been obtained for flow over isolated obstacles. This parametrization can only be verified with numerical simulation or with LDA; not with hot wire anemometry. The turbulence intensity parametrization can be used to predict discomfort or danger probability as a function of wind amplification factor. The affected area can be determined with a parametrization of the influence radius of a building as a function of building width and height.

Airport wind speeds used for the design in urban environments: the Eindhoven case

On the basis of measured field data, the paper evaluates the procedure to predict the wind velocity in the urban boundary layer in a town using available airport data. In particular, the accuracy of the prediction of velocity and wind direction and their statistical deviations are dealt with and design ramifications are discussed.

Spectral characteristics of wind induced pressures on a full scale building in suburban terrain

Wind and wind induced pressures have been measured on a square building with height to width ratio of 0.27 in suburban terrain. This paper presents the flow characteristics over the city and the spectral characteristics of the fluctuating wind induced pressures on the windward and leeward facade of the building. Measured cross spectra of the pressure fluctuations at windward and leeward side are underestimated by predictions using the quasi-steady theory.

Coherence of wind-induced pressures on buildings in urban areas: Set up of a full-scale experiment

Abstract Full-scale and wind-tunnel measurements are necessary to investigate the coherence of pressures on the surface of buildings in urban areas. This paper describes the set up of a series of full-scale measurements, performed on the main building of Eindhoven University of Technology.

Numerical simulation of wind in a built-up environment and experimental verification

Calculations using a second-order algebraic stress model are compared with wind tunnel and full-scale measurements for flow over a two-dimensional obstacle. The experiments show mutually good agreement. Outside the cavity, i.e. in front of the obstacle and at a distance of five obstacle heights downwind, calculations and experiments yield the same velocities and turbulent kinetic energies. However, in the cavity comparison is poor. This is caused by systematic errors in the anemometers. Therefore, it is the measurements in the cavity which are inaccurate and not the calculations.