Version 28 (modified by keevil8ga, 4 years ago) (diff)

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# Project Name

 Infrastructure CNRS_Coriolis Project (long title) Coriolis and Rotational effects on Stratified Turbulence Campaign Title (name data folder) 16CREST Lead Author Jeffrey Peakall Contributor Stephen Darby, Robert Michael Dorrell, Shahrzad Davarpanah Jazi, Gareth Mark Keevil, Jeffrey Peakall, Anna Wåhlin, Mathew Graeme Wells, Joel Sommeria, Samuel Viboud Date Campaign Start 12/09/2016 Date Campaign End 21/10/2016

# 1 - Objectives

Our primary objective is to measure detailed turbulence distributions within channelised gravity currents, as a function of Coriolis forces, concentrating on: i) the bottom boundary layer, ii) redistribution of turbulence within bends, and, iii) redistribution of turbulence at the interface between the gravity current and the ambient. These datasets will enable existing theory on the presence and influence of Ekman boundary layers to be tested, with important implication for the basal shear stress distributions, erosion, and the evolution of channels. These data on the distribution of turbulence will then be applied to i) examine the turbulence distribution in straight channels, ii) provide an analysis of secondary flow and associated turbulence around bends for the first time, and an assessment of how channelized flows alter as a function of Rossby numbers and therefore latitude, iii) assess how the morphodynamics of submarine channels vary as a function of the Rossby number, iv) explain the observed patterns of submarine channel sinuosity with latitude (Peakall et al., 2012; Cossu and Wells, 2013; Cossu et al., 2015), and, v) incorporate the entrainment data into numerical models of submarine channels, in order to address the unanswered question of how these flows traverse such large-distances across very low-angle slopes (Dorrell et al., 2014).Our primary objective is to measure detailed turbulence distributions within channelised gravity currents, as a function of Coriolis forces, concentrating on: i) the bottom boundary layer, ii) redistribution of turbulence within bends, and, iii) redistribution of turbulence at the interface between the gravity current and the ambient. These datasets will enable existing theory on the presence and influence of Ekman boundary layers to be tested, with important implication for the basal shear stress distributions, erosion, and the evolution of channels. These data on the distribution of turbulence will then be applied to i) examine the turbulence distribution in straight channels, ii) provide an analysis of secondary flow and associated turbulence around bends for the first time, and an assessment of how channelized flows alter as a function of Rossby numbers and therefore latitude, iii) assess how the morphodynamics of submarine channels vary as a function of the Rossby number, iv) explain the observed patterns of submarine channel sinuosity with latitude (Peakall et al., 2012; Cossu and Wells, 2013; Cossu et al., 2015), and, v) incorporate the entrainment data into numerical models of submarine channels, in order to address the unanswered question of how these flows traverse such large-distances across very low-angle slopes (Dorrell et al., 2014).

# 2 - Experimental setup:

## 2.1 General description

 Run Name Measurement Position Density Excess Input flow Rotation Rate Initial Water Depth Outflow Rate Run Time ADV Dwell Time $(kg\m3)$ $(ls-1)$ $(rad\s-1)$ $(m)$ $(ls-1)$ $(Minutes)$ $(s)$ Smooth_1 1 20 12 0 1 5.5 20 60 Smooth_2 1 20 12 0 1 12.0 20 60 Smooth_3 2 20 12 0 1 5.5 20 60 Smooth_4 3 20 12 0 1 5.5 20 60 Smooth_5 4 20 12 0 1 5.5 20 60 Smooth_6 1 20 12 0 1 5.5 20 30 Smooth_7 3 20 12 0 1 5.5 20 30 Smooth_8 4 20 12 0 1 5.5 20 30 Smooth_9 2 20 12 0 1 12.0 60 30

## 2.3 General description

 Notation Definition Valve Remarks $Q_0$ Input Density $12 \ (ls-1)$ $\Delta\rho$ Density Difference $20 \ (kg\m3)$ $W$ Channel Width $0.6 \ m$ $\nu$ Viscosity $10-6m2s-1$

## 2.4 Definition of the relevant non-dimensional numbers

Flow Reynolds number across the obstruction, $Re = Uh/\nu$.

Internal composite Froude number across the obstruction, $Fr = U/(g'h){1/2}$, $g' = g(\Delta\rho)/\rho_0$.

Rossby number, $Ro = U/fW$.