Single and collective fiber dynamics in micro-flows. Anke Lindner, PMMH-ESPCI, Paris, France

Transcription

1 Single and collective fiber dynamics in micro-flows Anke Lindner, PMMH-ESPCI, Paris, France COST conference, Porto, 2016

2 Fibers in interaction with viscous flows Industrial applications Paper industry 1m Lost circulation problems in oil wells Filtration and separation devices Biology 1mm Swimming micro-organisms Schlumberger Biofilm Streamers PhD, Gbedo, 2011, Toulouse Flow-sensors Sea Urchin Spermatozoid Wexler, AL, et al, JFM, 2013 Rusconi et al, J R Soc Interface, 2011 Large number of applications: real systems can be complex Need of controlled model systems to gain more fundamental understanding.

3 Our microfabrication and flow platform Microfluidic flow geometries Microfabrication of particles Insitu characterization of properties Perfect flow control Direct observation of microscopic particles under flow Dendukuri et al, Lab on chip, (2007) 50mm Wexler, AL et al, Bending of elastic fibres in viscous flows: the influence of confinement JFM, 2013, Berthet, AL et al, Single fiber transport in a confined channel: Microfluidic experiments and numerical study, Phys. Fluids, 2013, AL, Flow of complex fluids, Phys. Fluids, 2014 Duprat, AL, et al, In-situ measurement of mechanical properties of microfabricated fibers, LabOnChip, 2015

4 Large variety of well characterized model particles Microfabricated Particles UV lithography Self assembled fibers (magnetic colloids) Nano ribbons (courtesy Al Crosby) Scale bar 10 mm Bio-Particles Biopolymers (actin filaments) Active swimmer (e-coli bacteria)

5 Fiber transport in confined geometries Flow geometry Hele-Shaw cell Plug flow in the channel width Poiseuille flow in the channel height H Fiber geometry Top view W lateral confinement Cross-section transverse confinement

6 Fiber fabrication Projection photo-lithographie Photo sensitive fluid of PEGDA with photoinitiator: crosslinks under UV exposure Projecting a fiber 2D shape into channel Control of size, concentration, orientation: Control of fiber confinement by the channel height:

7 Single fiber transport What happens for different orientations? Berthet, AL, et al, PoF, 2013

8 Anisotropic transport velocity Experimental results Fiber is faster in perpendicular direction than parallel direction!

9 Origin of anisotripic transsport velocity Numerical and analytical results Side view Perpendicular fiber Parallel fiber Fiber is faster in perpendicular direction than parallel direction! Nagel, AL, et al, in preparation

10 Fiber drift Anisotropic transport velocity leads to fiber drift of inclined fibers Sedimenting fiber drifts due to anisotropic friction coefficient! g Transported and sedimenting fibers drift in opposite directions!

11 Fiber drift Anisotropic transport velocity leads to fiber drift of inclined fibers Sedimenting fiber drifts due to anisotropic friction coefficient! g Transported and sedimenting fibers drift in opposite directions!

12 Fiber drift can be tuned by confinement Drift angle a vs fiber orientation θ Drift angle increases with confinement Angle at which maximum drift is obtained varies with fiber orientation

13 Wall effect: oscillations (glancing)

14 Wall effect: oscillations (reversing)

15 Glancing Orbits (glancing and reversing) Reversing

16 Pole-Vaulting

17 Phase diagram

18 Phase diagram y θ y θ Collaboration F. Gallaire, EPFL, Lausanne Transport modes given by fiber angle and distance from lateral wall. Phase diagram function of lateral and transverse confinement. Duprat, AL et al, Fiber dynamics in confined channels, in preparation 2015

19 More complex shaped fibers Rotation and drift are observed. Stable orientations reached are function of fiber shape and confinement.

20 Clogging of constrictions? Parallel fibers: decreased permeability, temporary bridging Perpendicular fibers: clustering effects upstream of restriction AL, Phys. Fluids 2014 H. Berthet, PhD, 2012

21 Self-assembling super-paramagnetic colloids Super-paramagnetic colloids in channel Self-assembling in chains when magnetic field is applied Polymer chains around colloids to glue them together: permanent chains are formed 40µm Control of fiber dimensions from particle (750 nm diameter) and channel height (<80 µm)

22 Aggregate formation Formation and deformation of localized flocs, on defects at channel bottom. Collective flow of fiber networks AL, PoF, 2014 H. Berthet, PhD, 2012

23 E-coli bacteria in channel flows Complex shaped active particles

24 Bacteria transport in the bulk Jeffery orbit aligns helix with stream lines Direction of drift In the reference frame of the helix upper part and lower part see flows of opposite directions Due to the anisotropy in drag, both segments lead to a drift velocity in the z direction Spirals drift in vorticity direction, as a function of chirality! Marcos, PRL, 2009

25 Rheotaxis Explained by lift experienced by the helix of the flagella and drag on the body of the bacteria Bacteria fluxes in Poiseuille flows are complicated! Rheotaxis creates flux towards the walls. Marcos et al, PRL, 2009 Marcos et al, PNAS, 2012

26 At the surface? At vanishing shear rates, bacteria swim in circles. At small shear rates bacteria migrate upstream at surfaces. At larger shear rates, they orient perpendicular to the flow, leading to a preferred swimming direction. Kaya and Koser, Biophys. J. 2012

27 Combine surfaces with edges Bacteria under flow in a confined microchannel h=20mm w=200mm

28 Experimental observations Flux towards the edges Top surface Bottom surface Preferential bacteria transport at a given angle (function of the shear rate) with the flow.

29 Bacteria concentration at the surfaces and edges Surface concentration Edge concentration Bulk concentration bact/mm 3 Strong accumulation at walls. Competition between wall accumulation and shear. Asymmetric concentration at the edge, due to rheotaxis at the surfaces.

30 Bacteria transport at the surfaces Transversal velocity Longitudinal velocity Bacteria are transported downstream with the flow (except for very small shear-rates) Bacteria swim at a right angle compared to the flow for sufficiently high shear rates.

31 Arriving at the edge Bacteria is turned due to shear close or edge. Most bacteria face upstream.

32 Interaction of bacteria with walls Confined channel (channel height ~20 mm) Bacteria swim upstream on the side walls over long distances.

33 Upstream migration Above a certain shear rate (~20 s-1) nearly all bacteria swim upstream!

34 Swimming speed at the edges Peculiar transport at the edges. Bacteria swim in a one dimensional corridor. Can we design a geometry to use transport at the edges?

35 Experimental observations flow through a funnel No flow Confined channel W=200 mm W f = 40 mm L f =200 mm h =20 mm Moderate flow rate (22 mm/s) E-coli suspension in a minimal medium + 2 mm latex beads (flow visualization) High flow rate (45 mm/s) Altshuler, AL, et al, Soft Matter, 2012

36 n Long range densification after the funnel at moderate flow rate 200mm

37 Fibers Bacteria Marine Daïff Francois Gallaire Eric Clement, Paris Jeremie Gachelin (PhD), Paris Camille Duprat Mathias Nagel Nuris Figueroa (PhD), Paris Ernesto Altshuler, Havanna