Self-similar evolution of a body eroding in a fluid flow

Matthew N.J. Moore, Leif Ristroph, Stephen Childress, Jun Zhang, Michael J. Shelley

Research output: Contribution to journalArticle

Abstract

Erosion of solid material by flowing fluids plays an important role in shaping landforms, and in this natural context is often dictated by processes of high complexity. Here, we examine the coupled evolution of solid shape and fluid flow within the idealized setting of a cylindrical body held against a fast, unidirectional flow, and eroding under the action of fluid shear stress. Experiments and simulations both show self-similar evolution of the body, with an emerging quasi-triangular geometry that is an attractor of the shape dynamics. Our fluid erosion model, based on Prandtl boundary layer theory, yields a scaling law that accurately predicts the body's vanishing rate. Further, a class of exact solutions provides a partial prediction for the body's terminal form as one with a leading surface of uniform shear stress. Our simulations show this predicted geometry to emerge robustly from a range of different initial conditions, and allow us to explore its local stability. The sharp, faceted features of the terminal geometry defy the intuition of erosion as a globally smoothing process.

Original languageEnglish (US)
Article number116602
JournalPhysics of Fluids
Volume25
Issue number11
DOIs
StatePublished - Aug 30 2013

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ASJC Scopus subject areas

  • Computational Mechanics
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes

Cite this

Moore, M. N. J., Ristroph, L., Childress, S., Zhang, J., & Shelley, M. J. (2013). Self-similar evolution of a body eroding in a fluid flow. Physics of Fluids, 25(11), [116602]. https://doi.org/10.1063/1.4829644