Coriolis effects on turbulence structures in free surface jets

This paper examines the effects of background rotation on turbulence structures in free surface jets using physical experiments in a rotating laboratory. The experiments were conducted by discharging neutrally buoyant jets into a deep basin over a backward-facing step. Hot film anemometers were deployed for stationed measurements of two-dimensional turbulent velocities. By using the fluctuating velocities, an equivalent turbulence eddy was constructed and its principal angle and eddy ellipticity were defined. These two parameters are used to study the Coriolis effects on turbulence structures. In addition, the changes of the turbulence structures are manifested through statistical spectral distributions. Rotation is shown to affect the energy cascade, and the physical mechanisms for this result are examined through theoretical analyses. The Coriolis effects on these parameters and the spectra are inferred to affect the jet stream spreading. (C) 2000 Elsevier Science B.V. All rights reserved.