Turbulent structures in cylindrical density currents in a rotating frame of reference

ABSTRACT

Gravity currents are flows generated by the action of gravity on fluids with different densities. In some geophysical applications, modeling such flows makes it necessary to account for rotating effects, modifying the dynamics of the flow. While previous works on rotating stratified flows focused on currents of large Coriolis number, the present work focuses on flows with small Coriolis numbers (i.e. moderate-to-large Rossby numbers). In this work, cylindrical rotating gravity currents are investigated by means of highly resolved simulations. A brief analysis of the mean flow evolution to the final state is presented to provide a complete picture of the flow dynamics. The numerical results, showing the well-known oscillatory behavior of the flow (inertial waves) and a final state lens shape (geostrophic adjustment), are in good agreement with experimental observations and theoretical models. The turbulent structures in the flow are visualized and described using, among others, a stereoscopic visualization and videos as supplementary material. In particular, the structure of the lobes and clefts at the front of the current is presented in association to local turbulent structures. In rotating gravity currents, the vortices observed at the lobes front are not of hairpin type but are rather of Kelvin-Helmholtz type.

KEYWORDS:

• Gravity currents
• rotation effects
• turbulent flows
• direct numerical simulation

Acknowledgements

The work presented in this manuscript is part of the M.S. thesis of Jorge Salinas at Instituto Balseiro finished and published in 2014, with a scholarship by the National Commission of Atomic Energy of Argentina (CNEA). Mariano Cantero and Enzo Dari acknowledge the financial support of ANPCyT with PICT-2575, CNEA and CONICET. Mariano Cantero and Thomas Bonometti acknowledges the financial support of INPT with SMI 2015. Some of the computational time was provided by the Scientific Groupment CALMIP (project P1525), the support of which is greatly appreciated.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

ANPCyT (Fondo para la Investigación Científica y Tecnológica) [grant number PICT-2575]; INPT [grant number SMI 2015]; Scientific Groupment CALMIP [project number P1525].