# Grain flow

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[[Image:KelsoDunesAvalancheDeposits.JPG|thumbnail|Grain flows (sand avalanches) on the slip faces of [sand dunes](/source/sand_dunes) at [Kelso](/source/Kelso%2C_California) in the [Mojave Desert](/source/Mojave_Desert), [California](/source/California).]]
A '''grain flow''' is a type of [sediment-gravity flow](/source/sediment-gravity_flow) in which the fluid can be either air or water, acts only as a lubricant, and grains within the flow remain in suspension due to grain-to-grain collisions that generate a dispersive pressure to prevent further settling. Grain flows are very common in [aeolian](/source/Aeolian_processes) settings as grain avalanches on the slip faces of [sand dunes](/source/sand_dunes). By contrast, pure grain flows are rare in subaqueous settings, where the grains in a flow are generally held in suspension dominantly by [traction](/source/traction_(geology)), [saltation](/source/Saltation_(geology)), fluid [turbulence](/source/turbulence) and/or grain [buoyancy](/source/buoyancy) when the grains are floating in the clay matrix of a [mud flow](/source/mud_flow). However, grain-to-grain collisions are very important as a contributing process of sediment support in subaqueous, sand-rich, [high-density turbidity currents](/source/high-density_turbidity_currents). The high concentrations of sand that develop at the base of high-density flows brings grains close enough together that frequent grain-to grain collisions are inevitable and result in layers of sediment that are [inverse graded](/source/Inverse_grading) as the smaller grains are able to fall in between larger grains and settle out beneath them.<ref>Lowe, D.R. (1982), ''Sediment gravity flows: II. Depositional models with special reference to the deposits of high-density turbidity currents,'' Journal of Sedimentology, Society of Economic Paleonotlogists and Mineralogists, v. 52, p. 279-297.</ref>

== In metallurgy ==

In [metallurgy](/source/metallurgy), the grain flow refers to the [plastic deformation](/source/plastic_deformation) of [crystallite](/source/crystallite)s during [rolling](/source/Rolling_(metalworking)) or [forging](/source/forging).

{{main article|Texture (crystalline)}}

==Notes and references==
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Category:Sedimentology

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Adapted from the Wikipedia article [Grain flow](https://en.wikipedia.org/wiki/Grain_flow) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Grain_flow?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.