Evaluating and modelling the response of an individual to a sudden change in wind speed

The response of an individual to a sudden increase in wind velocity is important in terms of wind comfort and wind safety. This paper is concerned with the latter issue and outlines a series of physical and numerical experiments undertaken in order to evaluate the response of an individual to a sudden change in wind speed. The physical experiments were undertaken in the dynamic circuit of the Jules Verne Climatic Wind Tunnel at CSTB in Nantes, France and subjected 31 people to wind speeds up to 20 m/s. In all cases the wind speed increased from a mean value of zero to the target value in approximately 0.2 s. The wind speed required to cause loss of balance is shown to be a function of orientation and weight. In an attempt to understand the influence that gust frequency and mean velocity exert on wind safety criteria, a simple numerical model has been developed. The model is shown to agree reasonably well with the data pertaining to the physical experiments. Furthermore the model has been used in a predictive sense to evaluate response of a 50th percentile child to sudden changes in wind speed. It is shown that such a child is potentially very wind sensitive, with 30% reduction in the wind velocity required to cause loss of balance when compared to the 50th percentile adult male.