Experiments on the laminar oscillatory flow of wormlike micellar solutions

Abstract

We report new experimental results of the oscillatory flow of a solution of giant micelles in a narrow vertical tube. We explore small driving amplitudes (laminar flow) and a large range of driving frequencies. High-resolution particle image velocimetry measurements of the flow field in a meridional plane of the tube show that the velocity magnitude at the tube axis peaks at well-defined resonance frequencies, where the phase lag with the forcing changes abruptly. The velocity field is highly inflectional and eventually exhibits some hints of shear banding. The results are compared with theoretical predictions based on the upper-convected Maxwell and Oldroyd-B models of the linear shear rheology of the solution, and observed coincidences and discrepancies are discussed in detail.

Stokes layers in oscillatory flows of viscoelastic fluids

“…For water, the recirculation induced by the presence of the top and bottom endwalls seems not to have influence on the flow in the middle of the cylinder for aspect ratios above 20 [26]. In experiments with viscoelastic WLM solutions in a cylinder of 560 mm length and 50 mm diameter the recirculating flow at the top and bottom lids did not extend beyond 20 mm [27]. Suppose that the top and bottom lids oscillate in time according to z(t) = z 0 sin (ω 0 t).…”

“…indeed the highly reversing nature of the base flow and the presence of resonant frequencies [27,34,35]. In particular, figure 3 shows the experimental results obtained at the symmetry axis of the cylinder.…”

“…In both panels, solid dots represent experimental values measured by particle-image velocimetry, and solid lines the corresponding analytical results for an UCM fluid. Data extracted from [27].…”

Developments in the Flow of Complex Fluids in Tubes

“…The results of Andrienko et al [226] obtained in the very late 1990s were confirmed by the recent experimental and analytical research of Casanellas and Ortín [231,232] who reported analytical studies of the laminar oscillatory flow of Maxwell and Oldroyd-B type of viscoelastic fluids in rectangular and cylindrical cross-sectional tubes and experimental results of the oscillatory flow of a solution of giant micelles in a narrow vertical tube under small driving amplitudes in laminar flow and a large range of driving frequencies. Their theoretical analysis shows that there are resonant velocity peaks under certain conditions and that a very small additive Newtonian solvent contribution is sufficient to largely suppress the resonant behavior thereby confirming the conclusions of Andrienko et al [216].…”

Electrokinetic oscillatory flow and energy conversion of viscoelastic fluids in microchannels: a linear analysis

“…2003). Some significant deviations in the Maxwell behaviour are observed for intermediate- and high-frequency regimes for wormlike micellar solutions due to the Rouse-like behaviour of the individual entangled segments (Yesilata, Clasen & Mckinley 2006) and additional solvent stress (Casanellas & Ortín 2012).…”