Manuel A. Alves

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We investigate the stability of steady planar stagnation flows of a dilute polyethylene oxide (PEO) solution using T-shaped microchannels. The precise flow rate control and well-defined geometries achievable with microfluidic fabrication technologies enable us to make detailed observations of the onset of elastically-driven flow asymmetries in steady flows(More)
A precision-machined cross-slot flow geometry with a shape that has been optimized by numerical simulation of the fluid kinematics is fabricated and used to measure the extensional viscosity of a dilute polymer solution. Full-field birefringence microscopy is used to monitor the evolution and growth of macromolecular anisotropy along the stagnation point(More)
Wormlike micellar surfactant solutions are encountered in a wide variety of important applications, including enhanced oil recovery and ink-jet printing, in which the fluids are subjected to high extensional strain rates. In this contribution we present an experimental investigation of the flow of a model wormlike micellar solution (cetyl pyridinium(More)
financial support provided under program POCI2010 by FCT and FEDER (project POCI/EQU/59256/2004) We present a detailed numerical study of the flow of a Newtonian fluid through microrheometric devices featuring a sudden contraction-expansion. This flow configuration is typically used to generate extensional deformations and high strain rates. The excess(More)
a We determine both experimentally and numerically the onset of elastic flow instabilities in viscoelastic polymer solutions with different levels of shear thinning. Previous experiments realized in microfluidic serpentine channels using dilute polymeric solutions showed that the onset of elastic instabilities strongly depends on the channel curvature. The(More)
A biofouling simulation system consisting of a flow cell and a recirculation tank was used. The fluid circulates at a flow rate of 350 L· h⁻¹ in a semicircular flow cell with hydraulic diameter of 18.3 mm, corresponding to an average velocity of 0.275 m· s⁻¹. Using computational fluid dynamics for flow simulation, an average wall shear stress of 0.4 Pa was(More)
This work presents a numerical technique for simulating incompressible, isothermal, viscoelastic flows of fluids governed by the upper-convected Maxwell (UCM) and K–BKZ (Kaye–Bernstein, Kearsley and Zapas) integral models. The numerical technique described herein is an extension of the GENSMAC method to the solution of the momentum and mass conservation(More)
  • Mónica S Neves Oliveira, Manuel A Alves, Fernando T Pinho, Gareth H Mckinley
  • 2006
We study the flow of a Newtonian fluid through microfabricated hyperbolic contractions in detail. A set of planar converging geometries, with total Hencky strains ranging from 1 to 3.7, have been fabricated in order to produce a homogeneous extensional flow field within the contraction. The kinematics in the contraction region are investigated(More)
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