OSCILLATING GRIDS AS A SOURCE OF NEARLY ISOTROPIC TURBULENCE

Turbulence generated by vertical oscillations of a horizontal monoplan ar grid in homogeneous water contained in a tank was used to study cer tain properties of nearly isotropic turbulence. The cases of sustained oscillations and the removal of forcing after a period of oscillation s were considered. The former was used to evaluate the Eulerian-freque ncy spectra of nearly isotropic turbulence, and the velocity-time powe r law and spectral behavior of decaying turbulence were studied using the latter. The experimental observations are compared with available theoretical formulations as well as previous experimental observations .