Dynamics of viscoelastic fluid filaments in microfluidic devices

The effects of fluid elasticity and channel dimension on polymeric droplet formation in the presence of a flowing continuous Newtonian phase are investigated systematically by using different molecular weight (MW) poly(ethylene oxide) (PEO) solutions and varying microchannel dimensions with constant orifice width (w) to depth (h) ratio (w∕h=1∕2) and w=25μm, 50μm, 100μm, and 1mm. The flow rate is varied so that the mean shear rate is practically identical for all cases considered. Relevant times scales include inertia-capillary Rayleigh time τR=(Rmax3ρ∕σ)1∕2, viscocapillary Tomotika time τT=η0Rmax∕σ, and the polymer relaxation time λ, where ρ is the fluid density of the dispersed phase, σ is the interfacial tension, η0 is the zero shear viscosity of the dispersed polymer phase, and Rmax is the maximum filament radius. Dimensionless numbers include the elasticity number E=λν∕Rmax2, elastocapillary number Ec=λ∕τT, and Deborah number, De=λ∕τR, where ν=η0∕ρ is the kinematic shear viscosity of the fluids. Exper...

[1]  Gareth H. McKinley,et al.  The inertio-elastic planar entry flow of low-viscosity elastic fluids in micro-fabricated geometries , 2005 .

[2]  D. Bonn,et al.  Inhibition of the finite-time singularity during droplet fission of a polymeric fluid. , 2001, Physical review letters.

[3]  R. Larson,et al.  Brownian Dynamics Modeling of Flow-Induced Birefringence and Chain Scission in Dilute Polymer Solutions in a Planar Cross-Slot Flow , 2005 .

[4]  M. Renardy.  Similarity solutions for jet breakup for various models of viscoelastic fluids , 2002 .

[5]  S. Tomotika.  On the Instability of a Cylindrical Thread of a Viscous Liquid Surrounded by Another Viscous Fluid , 1935 .

[6]  L. Walker,et al.  Surface tension driven jet break up of strain-hardening polymer solutions , 2001 .

[7]  H. Stone,et al.  CAPILLARY BREAKUP OF A VISCOUS THREAD SURROUNDED BY ANOTHER VISCOUS FLUID , 1998 .

[8]  Radhakrishna Sureshkumar,et al.  Viscoelastic effects on the stability of wall-bounded shear flows , 2002 .

[9]  P. Schümmer,et al.  A new elongational rheometer for polymer solutions , 1983 .

[10]  N. Martys,et al.  Breakup of a fluid thread in a confined geometry: droplet-plug transition, perturbation sensitivity, and kinetic stabilization with confinement. , 2004, Physical review. E, Statistical, nonlinear, and soft matter physics.

[11]  Iterated stretching and multiple beads-on-a-string phenomena in dilute solutions of highly extensible flexible polymers , 2005, cond-mat/0502212.

[12]  A. Keller,et al.  Flow-induced chain fracture of isolated linear macromolecules in solution , 1986 .

[13]  A. Keller,et al.  Flow‐induced scission of isolated macromolecules , 1988 .

[14]  R. Shinnar,et al.  Breakup of a laminar capillary jet of a viscoelastic fluid , 1969, Journal of Fluid Mechanics.

[15]  Alvin U. Chen,et al.  Computational and experimental analysis of pinch-off and scaling. , 2002, Physical review letters.

[16]  P. S. Virk.  Drag reduction fundamentals , 1975 .

[17]  Daniel R. Lester,et al.  Drop formation dynamics of constant low-viscosity, elastic fluids , 2002 .

[18]  Gary W. Slater,et al.  Flow-induced chain scission as a physical route to narrowly distributed, high molar mass polymers , 2004 .

[19]  Justin J. Cooper-White,et al.  The effect of elasticity on drop creation in T-shaped microchannels , 2006 .

[20]  J. Cooper-White,et al.  Drop formation and breakup of low viscosity elastic fluids: Effects of molecular weight and concentration , 2006 .

[21]  G. McKinley,et al.  Stress relaxation and elastic decohesion of viscoelastic polymer solutions in extensional flow , 1996 .

[22]  W. R. Schowalter,et al.  Computation of a free jet with embedded drops , 2002 .

[23]  Chunfeng Zhou,et al.  Formation of simple and compound drops in microfluidic devices , 2006 .

[24]  James J. Feng,et al.  An experimental study of the coalescence between a drop and an interface in Newtonian and polymeric liquids , 2006 .

[25]  Chang Feng Li,et al.  Influence of rheological parameters on polymer induced turbulent drag reduction , 2006 .

[26]  Morton M. Denn,et al.  Elastic effects in flow of viscoelastic liquids , 1971 .

[27]  D. Weitz,et al.  Geometrically mediated breakup of drops in microfluidic devices. , 2003, Physical review letters.

[28]  D. Bonn,et al.  Droplet detachment and satellite bead formation in viscoelastic fluids. , 2005, Physical review letters.

[29]  E. Grens,et al.  Antimisting action of polymeric additives in jet fuels , 1984 .

[30]  J. Eggers,et al.  The beads-on-string structure of viscoelastic threads , 2003, Journal of Fluid Mechanics.

[31]  D. Bousfield,et al.  Nonlinear analysis of the surface tension driven breakup of viscoelastic filaments , 1986 .

[32]  J. Rothstein,et al.  Stable jets of viscoelastic fluids and self-assembled cylindrical capsules by hydrodynamic focusing. , 2005, Langmuir : the ACS journal of surfaces and colloids.

[33]  L. G. Leal,et al.  Dilute polystyrene solutions in extensional flows: Birefringence and flow modification , 1987 .

[34]  W. Jones,et al.  The stringiness of dilute polymer solutions , 1982 .

[35]  N. Akesson,et al.  Spray atomization characteristics as a function of pesticide formulations and atomizer design , 1994 .

[36]  W. Graessley.  Polymer chain dimensions and the dependence of viscoelastic properties on concentration, molecular weight and solvent power , 1980 .

[37]  J. Eggers.  Nonlinear dynamics and breakup of free-surface flows , 1997 .

[38]  O. Hassager,et al.  The role of surface tension on the elastic decohesion of polymeric filaments , 2001 .

[39]  E. Hinch,et al.  Effect of a spectrum of relaxation times on the capillary thinning of a filament of elastic liquid , 1997 .

[40]  S. Vanapalli,et al.  Universal scaling for polymer chain scission in turbulence , 2006, Proceedings of the National Academy of Sciences.

[41]  M. Mackley,et al.  Rheological characterization of the time and strain dependence for polyisobutylene solutions , 1994 .

[42]  Amy Q. Shen,et al.  Liquid crystal droplet production in a microfluidic device , 2006 .

[43]  H. Stone,et al.  Formation of dispersions using “flow focusing” in microchannels , 2003 .

[44]  A. Gañán-Calvo,et al.  Perfectly monodisperse microbubbling by capillary flow focusing. , 2001, Physical review letters.

[45]  C. Manke,et al.  Atomization of dilute polyisobutylene/mineral oil solutions , 1996 .

[46]  Gareth H. McKinley,et al.  Elasto-capillary thinning and breakup of model elastic liquids , 2001 .