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Project Name

InfrastructureCNRS_Coriolis
Project (long title)Coriolis and Rotational effects on Stratified Turbulence
Campaign Title (name data folder)16CREST
Lead AuthorJeffrey Peakall
ContributorStephen Darby, Robert Michael Dorrell, Shahrzad Davarpanah Jazi, Gareth Mark Keevil, Jeffrey Peakall, Anna Wåhlin, Mathew Graeme Wells, Joel Sommeria, Samuel Viboud
Date Campaign Start12/09/2016
Date Campaign End21/10/2016

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 NameMeasurement PositionDensity Excess Input flowRotation RateInitial Water DepthOutflow RateRun TimeADV 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

NotationDefinitionValveRemarks
$Q_0$ Input Density $12 \ ls-1$
$\rho_0$ 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, $Ro = U/fw$.

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