Front dynamics of elliptical gravity currents on a uniform slope

Abstract

In the present investigation, we report data from direct numerical simulations of elliptical, finite release, Boussinesq gravity currents propagating down a uniform slope. The study comprises a series of simulations of elliptical gravity currents on a range of slope angles. The shape parameters are varied to study the effects of the initial cross-sectional aspect ratio (Λ0) and mean height to lock radius ratio (Γ) on the dynamics of the gravity current. It is found that the long-time development of the current spatial mass distribution is influenced by its initial shape at smaller slope angles (θ=5∘ and 10∘) whereas the long-time motion of the gravity current is relatively insensitive to its initial shape but is sensitive to the slope angle. The switching of axes are observed for all the noncircular releases studied in the present work. Multiple acceleration phases are observed for the current center of mass in the case of the current with a small or moderate initial cross-sectional aspect ratio (Λ0=0.1, 0.2, 0.5, 1, and 2) whereas one single acceleration phase exists for the current with a large initial cross-sectional aspect ratio (Λ0=5 and 10). The Froude numbers (Fr) for the currents released with the same slope angle but different initial shapes are observed to attain a similar constant value after the second acceleration phase. The mean Froude number (Fr) is seen to increase with increasing slope angles. The mean height to lock radius ratio is found to affect only the early development of the current with little influence on the long-time evolution.