Generation of atmospheric turbulence in a wind tunnel

This report aims to contribute to the knowledge and characterization of grid generated turbulence in a wind tunnel. It starts with a theory introduction to turbulence where we bring together the classic approaches (Richardson-Kolmogorov equilibrium cascade) and more recent research. The latter includes the nonequilibrium dissipation law developed by [Valente and Vassilicos, 2011] and calculus methods such as set forth by [Puga and LaRue, 2017]. The study is based on two grids: an active grid in two different modes (open and random) and a regular and irregular passive grids. In terms of the means employed, the data is gathered using a hot-wire anemometer which makes it possible to have a high time resolution even though only one point and 1D turbulence is collected. In addition, the software used in the mathematical processing is MATLAB. The crucial parameters analyzed are the variations, the lengthscales (as well as their interaction) and dissipation rate constants, both equilibrium and nonequilibrium definitions. Some significant results have been found. In the first place Kolmogorov hypotheses are justified to hold true. Furthermore, there are some signs that the nonequilibrium law seems a plausible answer to some instabilities perceived. Finally, the vertical profiles of the irregular grid clearly show that the turbulence generated is inhomogeneous, which ushers in new lines of investigation