A new constitutive model for worm-like micellar systems - Numerical simulation of confined contraction-expansion flows

作者：Lopez Aguilar J E; Webster M F^*; Tamaddon Jahromi H R; Manero O

来源：Journal of Non-Newtonian Fluid Mechanics, 2014, 204: 7-21.

DOI：10.1016/j.jnnfm.2013.11.001

• Rising excess pressure drop
• Wormlike micelles
• High-elasticity solutions
• Bautista-Manero models
• Hybrid finite element/volume method
• Enhanced oil-recovery

This hybrid finite element/volume study is concerned with the modelling of worm-like micellar systems, employing a new micellar thixotropic constitutive model with viscoelasticity within network-structure construction-destruction kinetics. The work focuses on steady-state solutions for axisymmetric, rounded-corner, 4:1:4 contraction-expansion flows. This has importance in industrial and healthcare applications such as in enhanced oil-reservoir recovery. Material functions for the micellar models (time-dependent, thixotropic) have been fitted to match two different extensional configurations of the exponential Phan-Thien/Tanner (PTT) model (rubber network-based, non-thixotropic). This covers mild and strong-hardening response, and re solvent fraction, highly-polymeric (beta = 1/9) and solvent-dominated (beta=0.9) fluids. Solution results are described through normalised Excess Pressure Drop (EPD), vortex intensity and stream function, stress (N-1 and N-2), and f-functional data. EPD predictions with the new micellar models prove to be consistent (at low rates, some rising) with Newtonian results, contrary to the base-reference modified Bautista-Manero (MBM) results. Markedly different vortex intensity trends are found in comparing micellar and EPTT solutions, which correspond with N-2 - N-1 and f data. In order to address the highly-elastic regime for thixotropic materials, a convoluted approach between EPPT and micellar models has been proposed. Here, numerically stable solutions are reported for impressively large We up to 300 and new vortex structures are revealed.

• 出版日期2014-2