Decay of Weak Turbulence

A detailed experimental investigation of the structure of weak turbulence generated by various single and multiple‐stage grids has been made. The weak turbulent fields were limited to those having no interaction with the linear momentum wake of the grid. The present study covers a range of Reynolds numbers of turbulence between 70 and 3. Components of turbulence were found to have equipartition of energy within this range. When the Reynolds number of turbulence is $\text{<30}$ , the kinetic energy of turbulence decreases inversely as the square of decay time. All the length scales of turbulence increase as the square root of time, while the Reynolds number of turbulence decreases as the square root of time. Both the measured spectral and correlation functions show self‐preserving forms. The longitudinal correlation function is closer to a Cauchy than to a Gaussian distribution function. The resultant three‐dimension energy spectrum shows a weak but nonvanishing transfer of energy from low to high wavenumbers.