Download presentation

Presentation is loading. Please wait.

Published byAshton Stuart Modified over 3 years ago

1
On the origin of the vorticity-banding instability 5 cm 2 cm constant shear rate throughout the system multi-valued flow curve isotropic and nematic branch different concentrations shear-induced viscous phase not clear what the origin of the banding instability is

2
low high rolling flow within the bands normal stresses along the gradient direction normal streses generated within the interface of a gradient-banded flow ( S. Fielding, Phys. Rev. E 2007 ; 76 ; 016311 )

3
Binodal 0.00.20.40.60.81.0 0 1 2 [s ]. nem Vorticity banding Spinodals Tumbling wagging Critical point concentration 1 fd virus : L = 880 nm D = 6.7 nm P = 2200 nm ( P. Lettinga ) 0 1

4
almost crossed polarizers distinguish orientational order vorticity direction P A

5
12 3 4 5 6 7 8 1 2 3 4 5 6 7 8 stretching of inhomogeneities growth of bands Shear flow vorticity direction Gapwidth 2.0 mm ~ 1 mm A

6
band width growth rate 23 % : 35 % : heterogeneous vorticity banding interconnected disconnected

7
spinodal decomposition : nucleation and growth : ( with Didi Derks, Arnout Imhof and Alfons van Blaaderen )

8
tracking of a seed particle ( counter-rotating couette cell ) with Bernard Pouligny (Bordeaux)

9
increasing shear rate elastic instability for polymers : non-uniform deformation equidistant velocity lines Weissenberg or rod-climbing effect K. Kang, P. Lettinga, Z. Dogic, J.K.G. Dhont Phys. Rev. E 74, 2006, 026307-1 – 026307-12

10
New viscous phases can be induced by the flow (under controlled shear-rate conditions ) stress shear rate new phase homogeneous inhomogeneous personal communication with John Melrose

11
Stability analysis : discreteness of inhomogeneities along the flow direction is of minor importance : mass density gradient component of the body force z-dependence with the typical distance between inhomogeneities Brownian contributions +rod-rod interactions +flow-structure coupling linear bi-linear linear probability density for the position and orientation of a rod x y z J.K.G. Dhont and W.J. Briels J. Chem Phys. 117, 2002, 3992-3999 J. Chem Phys. 118, 2003, 1466-1478 z y

12
small large renormalized base flow probability linear contributions bi-linear contributions rod-rod interactions

13
unstable stable depends on the microstructural properties of the inhomogeneities 0.0 0.20.40.6 concentration

14
Wilkins GMH, Olmsted PD, Vorticity banding during the lamellar-to-onion transition in a lyotropic surfactant solution in shear flow, Eur. Phys. J. E 2006 ; 21 ; 133-143. Fischer P, Wheeler EK, Fuller GG, Shear-banding structure oriented in the vorticity direction observed for equimolar micellar solution, Rheol. Acta 2002 ; 41 ; 35-44. Lin-Gibson S, Pathak JA, Grulke EA, Wang H, Hobbie EK, elastic flow instability in nanotube suspensions, Phys. Rev. Lett. 2004 ; 92, 048302-1 - 048302-4. Vermant J, Raynaud L, Mewis J, Ernst B, Fuller GG, Large-scale bundle ordering in sterically stabilized latices, J. Coll. Int. Sci. 1999 ; 211 ; 221-229. Bonn D, Meunier J, Greffier O, Al-Kahwaji A, Kellay H, Bistability in non-Newtonian flow : rheology and lyotropic liquid crystals, Phys. Rev. E 1998 ; 58 ; 2115-2118. Micellar worms Nanotube bundles Colloidal aggregates -Worms - Entanglements - Shear-induced phase

15
Kyongok Kang Pavlik Lettinga Wim Briels

Similar presentations

OK

Nigel Clarke Department of Chemistry Durham University Effect of Shear Flow on Polymer-Polymer Miscibility: Theoretical Advances and Challenges With.

Nigel Clarke Department of Chemistry Durham University Effect of Shear Flow on Polymer-Polymer Miscibility: Theoretical Advances and Challenges With.

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on collection of primary data Ppt on spiritual leadership pdf Ppt on different occupations workers Ppt on media revolution tv Ppt on flora and fauna of kerala Ppt on cobb douglas production function Ppt on water softening techniques for managing Ms ppt online Free download ppt on sustainable development Option call put ppt on loop