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The importance of double diffusion to the settling of suspended material
Author(s) -
GREEN THEODORE
Publication year - 1987
Publication title -
sedimentology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.494
H-Index - 108
eISSN - 1365-3091
pISSN - 0037-0746
DOI - 10.1111/j.1365-3091.1987.tb00780.x
Subject(s) - settling , geology , sedimentation , diffusion , flux (metallurgy) , sediment , interflow , geomorphology , residence time (fluid dynamics) , hydrology (agriculture) , geotechnical engineering , groundwater , environmental science , materials science , thermodynamics , physics , environmental engineering , metallurgy
The vertical fingering motions which can occur when warm, salty water overlies colder, fresher water are important to the vertical flux of salt in the ocean. An analogous and not uncommon situation is that where turbid water overlies clearer and denser water. For the case of an originally sharp horizontal interface between the two water layers (associated, as an example with an interflow due to a warm, muddy river entering a stratified lake), the resulting downward sediment flux is compared with that occurring by way of gravitational settling. Rules are proposed to ascertain when the fingering effect could be important to sedimentation. For example, it seems that fingering could be of consequence in the situation where the sediment has a diameter of 2 μm and the upper layer is about 1°C warmer than the (clear) lower layer, when the upper‐layer concentration is 1 ppm. The effect of fingering on the residence time of a gravitationally stable turbid layer is calculated. Such layers may be more short‐lived than commonly thought.