Particle Laden Gravity Currents dynamics in highconcentration regimes

Jean Schneider,Yvan Dossmann,Yoann Cheny,Sébastien Kiesgen De Richter,Mickaël Delcey

doi:10.5194/egusphere-egu22-9141

Abstract

&lt;p&gt;LEMTA - UMR 7563 CNRS-UL - Universite de Lorraine, Nancy, France&lt;/p&gt;&lt;p&gt;&lt;br&gt;Particle-laden gravity currents (PLGC) are commonly found in estuaries&lt;br&gt;where rivers discharge suspended matters into the oceans. The dynamics of&lt;br&gt;these stratified flow is largely related to the properties of the suspended particles, such as their geometry, concentration, and particles size. While several&lt;br&gt;studies have focused on low concentration regimes (e.g. [1]), the physical mechanisms controlled by particle size and concentration are largely unknown for&lt;br&gt;volume fraction larger than 2 %.&lt;/p&gt;&lt;p&gt;&lt;br&gt;In order to investigate how the dynamics of PLGC is influenced by particle&lt;br&gt;concentration and particle size in high concentration regimes, we study the impact of different particle sizes ranging from 6&amp;#181;m to 85&amp;#181;m.&lt;/p&gt;&lt;p&gt;&lt;br&gt;The experimental lock-release device is composed of a tilted tank at a controlled angle in which a particle loaded fluid is released on an environment with&lt;br&gt;a controlled density. A particular focus is put on hypopycnal freshwater currents with high concentration suspended particles advancing through a heavier&lt;br&gt;environment. We follow the progress of the current with a high frequency CCD&lt;br&gt;camera. Quantitative data can then be determined using optical methods such&lt;br&gt;as Light Attenuation Technique which is extended to multiphase flows.&lt;/p&gt;&lt;p&gt;&lt;br&gt;Different flow regimes are observed depending on the concentration range and&lt;br&gt;particle size. These regimes highlight the competition between advective transport controlled by density difference and convective sedimentation. Indeed four&lt;br&gt;mechanisms are observed in these regimes, respectively horizontal advection at&lt;br&gt;the surface, sedimentation, advection parallel to the tank bottom, and particle&lt;br&gt;rise of due to buoyancy effects of the surrounding fluid.&lt;/p&gt;&lt;p&gt;&lt;br&gt;References&lt;br&gt;[1] Bruce R. Sutherland et al. &amp;#8220;Particle settling from constant-flux surface&lt;br&gt;gravity currents and a near-stationary particle-bearing layer&amp;#8221;. In: Physical&lt;br&gt;Review Fluids 6.6 (June 10, 2021). Publisher: American Physical Society,&lt;br&gt;p. 063802. doi: 10 . 1103 / PhysRevFluids . 6 . 063802. url: https : / /&lt;br&gt;link . aps . org / doi / 10 . 1103 / PhysRevFluids . 6 . 063802 (visited on&lt;br&gt;10/25/2021)&lt;/p&gt;

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