Simulación directa de turbulencia en corrientes de gravedad con efecto Coriolis

Abstract

Gravity currents are flows generated by horizontal pressure gradients resulting from the effect of gravity on fluids of different density. When they occur in nature, gravity currents have a strong nonlinear behavior and have a wide range of temporal and spatial scales. In addition, the rotation of the earth raises the level of complexity of gravity currents due to the effect of the Coriolis force. This work addresses rotating gravity currents in planar geometry by direct numerical simulation (DNS). The simulations allow for a detailed analysis of the flow development, macroscopic parameters of the flow and turbulence structure. Simulations were performed using a pseudospectral code that uses Fourier expansions in the two horizontal directions and Chebyshev expansions in the vertical direction. This work documents in detail the code developed and the validation performed by comparing a simulation with experimental observations and theoretical predictions. This work also reports on two simulations with different rotation speeds. It was found that the flow rotation restricts the development of the current in the propagating direction, and induces oscillations in the front position. The frequency of these oscillations varies linearly with the rotation speed. Finally, this work also reports on Kelvin-Helmholtz-like turbulent structures at the front of the current produced by the rotation of the system.