Effect of rotational ambient, discharge and inflow density on the formation and evolution of a density-driven current over a steep slope

Abstract

This numerical study investigates the evolution of constant-flux high density fluid introduced vertically to a rotational low-density ambient through a circular inlet situated on top of a cone, which is mounted to the bottom of the simulation domain. The progress of the high density fluid over the bottom-mounted cone with steep side-wall slope of 39° is numerically modeled using large eddy simulations (LES). In the study, two different inflow discharges, three different inflow density values and three different ambient rotations are considered. The effect of rotational ambient and its relation to vertically-released inflow discharge and density on the formation and evolution of the current is evaluated using an effective Ekman number and a Rossby analogue of the flow calculated based on the inflow and ambient conditions. Mean radius of deformation, Reynolds and Froude numbers of the current are calculated based on the mean reduced gravitational acceleration and mean depth of the current at the end of the slope. Their relation to entrainment is discussed. A Taylor-column like formation around the inlet is observed for flows with small Rossby analogue. The entrainment is observed to increase with increasing radius of deformation. The combined effect of Reynolds and Froude numbers on entrainment is found to be less noticeable for currents propagating on a bottom mounted cone at 1000 < ReFr < 250,000 in the rotational ambient conditions considered in the present study.

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Acknowledgements

This study was funded by Scientific and Technological Research Council of Turkey (TUBITAK) under the Science Fellowship Program BIDEB-2232 (Grant number 115C131) and was conducted at the Hydraulics Laboratory of Middle East Technical University, Ankara, Turkey. I would like to thank Prof. Dr. Burcu Altan Sakarya for acting as the host of this grant and Ms. Necla Cankaya Lostar for all her help on the administration front.

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Correspondence to Talia Tokyay.

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Tokyay, T. Effect of rotational ambient, discharge and inflow density on the formation and evolution of a density-driven current over a steep slope. Environ Fluid Mech 21, 383–403 (2021). https://doi.org/10.1007/s10652-021-09778-6

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Keywords

  • Constant-flux
  • Density-driven flow
  • Rossby analogue
  • Reynolds number
  • Froude number
  • LES
  • Taylor-column
  • Radius of deformation