Enhanced displacement of a liquid pushed by a viscoelastic fluid.

J. Avendano (1) , Nicolas Pannacci (1) , Benjamin Herzhaft (1) , Patrick Gateau (1) , Philippe Coussot (2)

1 IFPEN - IFP Energies nouvelles
2 navier umr 8205 - Laboratoire Navier

We consider the displacement, in a rectangular channel, of a Newtonian oil pushed by different types of liquids (Newtonian, shear-thinning, viscoelastic) of slightly higher apparent viscosity. ln the absence of viscoelastic effects the interface between the two fluids becomes sharper at larger velocities, so that the thickness of the lateral film left behind increases with the flow rate. On the contrary, with a viscoelastic fluid, the shape of the interface is almost independent of the velocity so that the thickness of the lateral film is approximately constant. Moreover this thickness decreases when the ratio of normal to tangential stresses increases, suggesting that this effect can be attributed to normal stress differences. A heuristic theoretical approach tends to confirm this statement.

Keywords: Channel flow; Viscoelastic fluid; Interface; viscosity; velocity

Domains: Chemical Sciences; Theoretical and/or physical chemistry

J. Avendano, Nicolas Pannacci, Benjamin Herzhaft, Patrick Gateau, Philippe Coussot. Enhanced displacement of a liquid pushed by a viscoelastic fluid.. Journal of Colloid and Interface Science, 2013, 410 (November), pp.172-180. ⟨10.1016/j.jcis.2013.08.014⟩. ⟨hal-01071696⟩