We present new experimental results on the development of turbulent spots in channel flow. The internal structure of a turbulent spot is measured, with Time Resolved Stereoscopic Particle Image Velocimetry. We report the observation of travelling-wave-like structures at the trailing edge of the turbulent spot. Special attention is paid to the large-scale flow surrounding the spot. We show that this large-scale flow is an asymmetric quadrupole centred on the spot. We measure the time evolution of the turbulent fluctuations and the mean flow distortions and compare these with the predictions of a nonlinear reduced order model predicting the main features of subcritical transition to turbulence.
Abstract. In this paper, on the background of a short overview of the recent advances in the field of Environmental Wind Engineering (EWE), a comparison of wind tunnel experiment and numerical simulation for some cases of airflow around an urban layout have been reported. The purpose of the study is quantitative and qualitative comparison of measurements in the wind tunnel as well as numerical simulation using Ansys Fluent software. The study is concerned mostly with the analysis of parameters which are essential in the building industry, such as pressure and velocity fields. In the numerical analysis the k-ε realizable model of turbulence with the basic model of boundary layer -Standard Wall Treatment, were used. Particular attention has been paid to accurate depiction of the conditions on the inlet and the selection of suitable computing.
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