顆粒流

顆粒流（）是一種重力流，其中流體（空氣或水），主要是提供潤滑的作用Fanjing Meng, Kun Liu, Wei Wang. (2015) The Force Chains and Dynamic States of Granular Flow Lubrication. Tribology Transactions 58:1, pages 70-78.，顆粒在流體中能保持懸浮狀態，是由於顆粒與顆粒之間的碰撞，從而產生分散壓力François Legros; Can Dispersive Pressure Cause Inverse Grading in Grain Flows?. Journal of Sedimentary Research 2002;; 72 (1): 166–170. doi: https://doi.org/10.1306/041301720166，而使顆粒不會沉澱D. R. Lowe; Grain flow and grain flow deposits. Journal of Sedimentary Research 1976;; 46 (1): 188–199. doi: https://doi.org/10.1306/212F6EF1-2B24-11D7-8648000102C1865D。最常見顆粒流是在風成環境中，顆粒因為順沙丘斜面上下滑而形成Carrie Breton, Nicholas Lancaster, William G. Nickling (2008) Magnitude and frequency of grain flows on a desert sand dune, Geomorphology, Volume 95, Issues 3–4, Pages 518-523, ISSN 0169-555X,https://doi.org/10.1016/j.geomorph.2007.07.004.。相比之下，顆粒流在水下環境中很少。通常顆粒在水中保持懸浮狀態是依賴顆粒的牽引、跳躍、以及流體的湍流作用。在泥流中，顆粒對粘土基質的相對漂浮力，也讓顆粒保持懸浮狀態Iverson, R. M. (1997), The physics of debris flows, Rev. Geophys., 35( 3), 245– 296, doi:10.1029/97RG00426. 。在高密度濁流中，底部沙子濃度較高，顆粒間的碰撞能使沙顆粒保持懸浮狀態。較小的顆粒，因爲沒有碰撞反而先沉澱在沙顆粒之下， 造成反向粒级层理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. 。
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Category:沉积学