New paper in Journal of Fluid Mechanics

A paper describing the turbulent field of an oscillating flow in a rotating environment (also called Stokes-Ekman boundary layer, SEBL) was recently published in Journal of Fluid Mechanics. The paper is the result of a long-term collaboration[1]^,[2] between OGS and the Department of Civil and Environmental Engineering of the University of Trieste.

Turbulence in SEBL was investigated by means of numerical Large-eddy simulations (LES), which solve directly the energy-carrying scales of motion, while parameterising the smallest isotropic and dissipative scales using a sub-grid scale model.

The SEBL studied in this work is the prototype of a water column driven by a semi-diurnal tidal current that is flowing parallel to the east-west direction, and has important geophysical applications. The effect of rotation was studied at three different latitudes in the Northern hemisphere (polar, mid-latitude and quasi-equatorial cases). The results show that the rotation greatly influences the polar case, narrowing the range of phases of oscillation affected by turbulence and redistributing the energy among the three spatial directions. Elliptical trajectories are observed at all the vertical levels. In the non-polar cases, the background rotation is too weak to significantly change the turbulent field, but an asymmetry between the two semi-periods of oscillation develops when latitude decreases, revealing an enhanced (reduced) turbulent activity in the second (first) semi-period, when the tidal forcing flows from east (west).