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The AAPG/Datapages Combined Publications Database

Journal of Sedimentary Research (SEPM)

Abstract


Journal of Sedimentary Petrology
Vol. 49 (1979)No. 1. (March), Pages 287-293

The Threshold of Grain Motion Under Oscillatory Flow in a Laboratory Previous HitWaveNext Hit Channel

John R. Dingler

ABSTRACT

The threshold of grain motion under Previous HitwaveNext Hit-induced fluid motion has been studied using Previous HitwaveNext Hit periods of two to ten seconds in a large laboratory Previous HitwaveNext Hit channel. The sand beds consisted of well-sorted material of quartz density, and the experiments covered a grain-size range of 0.018 to 0.145 centimeters. In all cases the gram diameter was such that the flow was in either the hydraulically smooth or the transitional flow regime. The results correlate well with the data from the oscillating-bed experiments of Bagnold (1946), suggesting that the oscillating-bed technique satisfactorily reproduces near-bottom motions at least for this set of conditions.

The data from both these studies best fit the non-dimensional Previous HitequationNext Hit

^ggrs T2/^rgrD = 290(d0/D)4/3 (^rgr^ggrsD32)-1/9

where ^ggrs = (^rgrs - ^rgr)g, ^rgrs and D are the grain density and median diameter respectively, µ and p are the fluid viscosity and density respectively, T is the Previous HitwaveNext Hit period, d0 is the near-bottom orbital diameter per Previous HitwaveTop cycle, and g is the acceleration of gravity. For material of quartz density in sea water, this relation becomes

T = 0.17(d02/D)1/3 (sec).


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