A study of weak bed load over a plane bed is presented with a particular focus on the motion and diffusion of individual particles that were tracked along their movements. Grain position, velocity and acceleration were measured with particle-scale resolution; ensemble statistics over a significant sample of particle trajectories were then computed, enabling unsteady phases of particle motion (corresponding to entrainment and disentrainment) to be identified. Based on the experimental findings, a physically-based conceptual model for particle kinematics consisting of an initial (entrainment) unsteady phase, a quasi-steady phase, and a final (disentrainment) unsteady phase is explored. The unsteadiness effects in particle dispersion due to entrainment and disentrainment, typically overlooked in previous studies, are explicitly quantified by analysing the time evolution of the particle position variance. Starting with a previously published model of particle diffusion, a refined model is proposed which explicitly accounts for the unsteadiness effects in particle motion.

Particle motion and diffusion at weak bed load: accounting for unsteadiness effects of entrainment and disentrainment

CAMPAGNOL, JENNY;RADICE, ALESSIO;BALLIO, FRANCESCO;
2015-01-01

Abstract

A study of weak bed load over a plane bed is presented with a particular focus on the motion and diffusion of individual particles that were tracked along their movements. Grain position, velocity and acceleration were measured with particle-scale resolution; ensemble statistics over a significant sample of particle trajectories were then computed, enabling unsteady phases of particle motion (corresponding to entrainment and disentrainment) to be identified. Based on the experimental findings, a physically-based conceptual model for particle kinematics consisting of an initial (entrainment) unsteady phase, a quasi-steady phase, and a final (disentrainment) unsteady phase is explored. The unsteadiness effects in particle dispersion due to entrainment and disentrainment, typically overlooked in previous studies, are explicitly quantified by analysing the time evolution of the particle position variance. Starting with a previously published model of particle diffusion, a refined model is proposed which explicitly accounts for the unsteadiness effects in particle motion.
2015
Bed load, disentrainment, entrainment, sediment acceleration, sediment diffusion, sediment motion, sediment velocity
File in questo prodotto:
File Dimensione Formato  
11311-969474_Radice.pdf

accesso aperto

: Post-Print (DRAFT o Author’s Accepted Manuscript-AAM)
Dimensione 3.65 MB
Formato Adobe PDF
3.65 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/969474
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 41
  • ???jsp.display-item.citation.isi??? 34
social impact