| Popis: |
The Shields entrainment function, extrapolated from bed load movement to predict the threshold of particle motion, appears deficient in analyzing incipient shear data for fluid-sediment combinations encompassing a wide range of relative densities. Equations describing incipient dynamic equilibrium, solved semiempirically, indicate additional density considerations that must be included in an attempt to correlate initial movement for all possible sedimentation density ratios. This and other experimental investigations also indicate any entrainment function to be dependent on the state of the bed and corresponding turbulence. Other factors which might be influential on the threshold of particle movement are mentioned. |
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