Wall effects on the transportation of a cylindrical particle in power-law fluids

Abstract

is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible.This is an author-deposited version published in: https://sam.ensam.eu Handle ID: .http://hdl.handle.net/10985/8454 To cite this version :Antoine DESPEYROUX, Abdelhak AMBARI, Abderrahim BEN RICHOU -Wall effects on the transportation of a cylindrical particle in power-law fluids -Journal of Non-Newtonian Fluid Mechanics -Vol. 166, n°19-20, p.1173-1182 -2011 Any correspondence concerning this service should be sent to the repository b s t r a c tThe present work deals with the numerical calculation of the Stokes-type drag undergone by a cylindrical particle perpendicularly to its axis in a power-law fluid. In unbounded medium, as all data are not available yet, we provide a numerical solution for the pseudoplastic fluid. Indeed, the Stokes-type solution exists because the Stokes' paradox does not take place anymore. We show a high sensitivity of the solution to the confinement, and the appearance of the inertia in the proximity of the Newtonian case, where the Stokes' paradox takes place. For unbounded medium, avoiding these traps, we show that the drag is zero for Newtonian and dilatant fluids. But in the bounded one, the Stokes-type regime is recovered for Newtonian and dilatant fluids. We give also a physical explanation of this effect which is due to the reduction of the hydrodynamic screen length, for pseudoplastic fluids. Once the solution of the unbounded medium has been obtained, we give a solution for the confined medium numerically and asymptotically. We also highlight the consequence of the confinement and the backflow on the settling velocity of a fiber perpendicularly to its axis in a slit. Using the dynamic mesh technique, we give the actual transportation velocity in a power-law ''Poiseuille flow'', versus the confinement parameter and the fluidity index, induced by the hydrodynamic interactions.

Steady State of Motion of Two Particles in Poiseuille Flow of Power-Law Fluid

“…Due to its fundamental and practical significance, there have been a large number of theoretical, experimental, and numerical studies on the migration of rigid particles in a confined flow. About the migration of particles in a Newtonian fluid, we can get some intuitions or results from available experimental and numerical results [1,[4][5][6][7], but in non-Newtonian fluids, the results could be completely different [8][9][10][11][12][13]. Non-Newtonian fluids have significantly different rheological attributes than Newtonian fluids in their viscoelasticity and their apparent viscosity varies with shear rate.…”