G. Pennacchioni et al., Finite-element modelling of simple shear flow in Newtonian and non-Newtonian fluids around a circular rigid particle, J STRUC GEO, 22(5), 2000, pp. 683-692
The flow perturbation around a circular rigid particle during simple shear
deformation has been investigated for both Newtonian and non-Newtonian (pow
er-law) fluids by finite-element modelling. If the particle is rotating und
er the applied shear couple and no-slip occurs at the particle-fluid interf
ace, a 'bow-tie-shaped' streamline pattern results for both Newtonian and p
ower-law fluids and the shape of streamlines does not change noticeably if
the stress exponent (n) is changed. In contrast, if the fluid is allowed to
separate from the particle, a 'double-bulge-shaped' flow develops in the c
ase of Newtonian fluids, and the type of streamline pattern is influenced b
y n. We suggest that both stair-stepping and non-stair-stepping geometries
of porphyroclast tails may be produced in mylonites, depending on the degre
e of coherence between the porphyroclasts and the embedding matrix. A diffe
rent behaviour of the fluid-particle interface may occur as the result of c
hanging fluid rheology, owing to the contrasting stress fields developed fo
r Newtonian and non-Newtonian fluids. (C) 2000 Elsevier Science Ltd. All ri
ghts reserved.