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On particle separation from turbulent particle plumes in a cross-flow

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Peer-reviewed

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Article

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Abstract

jats:pWe present new experiments of particle-driven turbulent plumes issuing from a constant source of dense particle-laden fluid, with buoyancy flux, jats:inline-formula jats:alternatives <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S002211202101065X_inline1.png" /> jats:tex-mathB</jats:tex-math> </jats:alternatives> </jats:inline-formula>, in a uniform horizontal current, jats:inline-formula jats:alternatives <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S002211202101065X_inline2.png" /> jats:tex-mathu</jats:tex-math> </jats:alternatives> </jats:inline-formula>. Experiments show that a turbulent, well-mixed plume develops, in which the downward vertical speed jats:inline-formula jats:alternatives <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S002211202101065X_inline3.png" /> jats:tex-mathw</jats:tex-math> </jats:alternatives> </jats:inline-formula> decreases with depth jats:inline-formula jats:alternatives <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S002211202101065X_inline4.png" /> jats:tex-mathz</jats:tex-math> </jats:alternatives> </jats:inline-formula> according to jats:inline-formula jats:alternatives <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S002211202101065X_inline5.png" /> jats:tex-mathw=0.76(B/uz)1/2</jats:tex-math> </jats:alternatives> </jats:inline-formula> while the horizontal speed rapidly asymptotes to the current speed jats:inline-formula jats:alternatives <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S002211202101065X_inline6.png" /> jats:tex-mathu</jats:tex-math> </jats:alternatives> </jats:inline-formula>, provided that the Stokes settling speed of the particles jats:inline-formula jats:alternatives <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S002211202101065X_inline7.png" /> jats:tex-mathMisplaced &v&lt;0.92 wv&lt;0.92 w</jats:tex-math> </jats:alternatives> </jats:inline-formula>. For jats:inline-formula jats:alternatives <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S002211202101065X_inline8.png" /> jats:tex-mathMisplaced &v &gt; 0.92 wv &gt; 0.92 w</jats:tex-math> </jats:alternatives> </jats:inline-formula>, the particles separate from the plume fluid, and their depth jats:inline-formula jats:alternatives <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S002211202101065X_inline9.png" /> jats:tex-mathz</jats:tex-math> </jats:alternatives> </jats:inline-formula> increases according to the simple sedimentation trajectory jats:inline-formula jats:alternatives <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S002211202101065X_inline10.png" /> jats:tex-mathdz/dx=v/u</jats:tex-math> </jats:alternatives> </jats:inline-formula>. As the particles sediment, they form clusters of particles, which lead to fluctuations in the particle load with position, but do not appear to change the time-average sedimentation speed. We explore the impact of these results for deep-sea mining, in which the fate of the plume water as well as the particles is key for assessing potential environmental impacts.</jats:p>

Description

Keywords

plumes/thermals, sediment transport

Journal Title

Journal of Fluid Mechanics

Conference Name

Journal ISSN

0022-1120
1469-7645

Volume Title

932

Publisher

Cambridge University Press (CUP)