Calibration and validation of a full-scale experimental model for the study of drowning victims

Abstract

There is currently no accurate and comprehensive model for the search of drowning victims in urban areas. Therefore, this thesis aims to contribute to the creation of such a model, by focusing on the calibration and validation of a wind tunnel experimental setup performed on a full-scale model. To achieve this, existing search for drowning persons models and their equations are analysed, fluid dynamics models applied to the human body are also reviewed, as well as papers on the position of a drowning person's body. This led to the identification of two essential parameters for such a model, which are the projected area and drag coefficient of a drifting body, and some ranges of values in which they should lie. To obtain results for the projected surface area parameter, several data acquisitions are made on a full-size dummy, using a laser scanning method and photogrammetry. Once these data collected, they allow the creation of a 3D digital model that can be adjusted according to the desired configuration in order to be adaptable to the experiments that will be carried out later. The projected surface of the dummy is calculated for a series of rotations along different axes in order to establish an initial database that can be used later. Then, the experimental setup for obtaining the drag coefficient values is establish in the wind tunnel on the full-scale model. This is carried out on the full-scale model after it was modified so that it can be placed as desired in the wind tunnel. The speed range is between 3.1 and 9.4 m/s with Reynolds numbers in a range between 9.3*10E5 and 3*10E6. This wind tunnel experiment provides a first estimation of the drag coefficient values of the full-scale model and these values are compared with other literature results obtained in wind tunnels in various fields such as cycling, skiing or skating. Finally, the prospects for improving the experimental set-up and the results obtained during the 3D digitisation will be discussed.