Nikuradse and Shields: turbulent roughness controls shear stress at incipient sediment transport
Résumé
A comparison of Nikuradse (1933) data for Darcy friction in roughened turbulent pipe flows against measurements of dimensionless shear stress at incipient transport from Shields (1936) and later authors reveals that the onset of entrainment of cohesionless sediment is related to turbulent roughness through a simple one-parameter correlation corrected by the ratio of fluid and solid densities to the power of one-third. This suggests that turbulent roughness governs the local Coulomb-like surface friction that lifts particles from a planar sediment bed, whether turbulent liquid or gas continua are involved.
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Licence : Copyright (Tous droits réservés)