Scalings and decay of homogeneous, nearly isotropic turbulence behind a jet array

Homogeneous and isotropic turbulence can be generated by many different mechanisms, from classical passive grids to jet arrays. By using high-speed jets, a jet array becomes a promising way to produce intense turbulence with large energy dissipation rates in water and wind tunnels. In this paper, a systematic experimental investigation was conducted to understand how the turbulence decay scales with the jet velocity, nozzle size, and nozzle spacings. Three-dimensional particle tracking was performed to quantify the spatial distribution of different turbulent characteristics. Combined with several previous experiments focusing on near-field measurements, our results provide a clear picture of the decay of the kinetic energy and the energy dissipation rate as well as the development of the inhomogeneity and anisotropy of turbulence generated by a jet array. Suggestions and design considerations for future wind and water tunnels are also provided.