Dynamics of floating objects at high particulate Reynolds numbers

H. Ghaffarian, D. Lopez, E. Mignot, H. Piegay, and N. Riviere
Phys. Rev. Fluids 5, 054307 – Published 28 May 2020

Abstract

The motion of high Reynolds number objects at free surfaces is a general problem that has many industrial and ecological applications, such as hazard assessment due to driftwood in rivers or motion of plastic patches in the oceans. Modeling such object trajectories in a flow can be done assuming the object to be a tracer or using Newton's second law in the form of the Basset-Boussinesq-Oseen equation. In many studies, however, the latter approach can be difficult to implement due to the presence of complex forces at play and a high computational cost, thus knowing the validity of the tracer model can be very useful for practical applications. In this work, we study theoretically and experimentally the dynamics of high Reynolds number floating objects in one- and two-dimensional free surface flows. We first verify that the two-dimensional surface version of the Basset-Boussinesq-Oseen equation can accurately model floating object trajectories. Following our theoretical analysis, we introduce a characteristic response distance noted λ that scales the acceleration distance of a floating object, and we show that it is about two to four times the body length in the streamwise direction. The dimensionless parameter λ obtained by normalizing λ by a flow length scale then plays a role analogous to that of the Stokes number at low particulate Reynolds number. Moreover, we show that once the floating object reaches the flow velocity, or if at any given time its velocity is equal to that of the flow, the floating object behaves like a tracer, regardless of λ. These results can greatly simplify the analyses and computations of the motion of floating objects at high particulate Reynolds number, first by identifying a characteristic distance λ scaling the length of the acceleration phase, and then by showing that once the flow velocity is reached, the object is transported as a passive tracer.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Received 20 June 2019
  • Accepted 1 April 2020

DOI:https://doi.org/10.1103/PhysRevFluids.5.054307

©2020 American Physical Society

Physics Subject Headings (PhySH)

Fluid Dynamics

Authors & Affiliations

H. Ghaffarian*

  • Univ Lyon, INSA Lyon, Ecole Centrale de Lyon, Université Claude Bernard Lyon I, CNRS, LMFA, UMR 5509, 20 avenue Albert Einstein, F-69621 VILLEURBANNE, France and Univ Lyon, UMR 5600, Environnement-Ville-Société CNRS, F-69362 Lyon, France

D. Lopez and E. Mignot

  • Univ Lyon, INSA Lyon, Ecole Centrale de Lyon, Université Claude Bernard Lyon I, CNRS, LMFA, UMR 5509, 20 avenue Albert Einstein, F-69621 VILLEURBANNE, France

H. Piegay

  • Univ Lyon, UMR 5600, Environnement-Ville-Société CNRS, F-69362 Lyon, France

N. Riviere

  • Univ Lyon, INSA Lyon, Ecole Centrale de Lyon, Université Claude Bernard Lyon I, CNRS, LMFA, UMR 5509, 20 avenue Albert Einstein, F-69621 VILLEURBANNE, France

  • *hossein.ghaffarian@insa-lyon.fr

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 5, Iss. 5 — May 2020

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review Fluids

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×