Deformation of viscoelastic drop is studied and reported computationally in a microscale flow with sudden constriction. The effect of polymeric viscosity on deformation of viscoelastic fluid is studied in a two dimensional, two-phase viscoelastic drop- Newtonian matrix system at Reynolds number varying from, Re = 2 to Re = 10. The effect of polymeric viscosity is studied by varying the value of solvent viscosity ratio β. The Finitely Extensible Non-linear Elastic– Peterlin (FENE-P) model is used to model the viscoelastic drop. Volume of fluid (VOF) method is used to track the interface of the viscoelastic drop. The simulation was performed using open source solver Basilisk. The flow is actuated by giving uniform velocity at the inlet and a constant pressure at the outlet. No-slip boundary condition is applied at the walls of constricted microchannel. For viscoelastic stress tensor Neumann boundary conditions are applied&nbsp;at microchannel walls other than inlet and outlet wall. The viscoelastic drop with lower polymeric viscosity and higher solvent viscosity seemed to undergo appreciable deformation inside constricted microchannel when subjected to sudden contraction. The deformation behaviour were studied and reported for different drop diameter. To reduce the effect of sharp corner points on the drop deformation, adaptive mesh refinement for the volume fraction is applied. The deformation behaviour of viscoelastic drop inside constricted microchannel considerably differ&nbsp;from the shear driven flow inside straight channel without sudden constriction. Low polymeric viscosity of a viscoelastic fluid corresponds to a dilute polymeric solution, its viscoelastic behaviour is best explained by seeing its deformation under high shear flows inside microchannel. The deformation observed at higher solvent viscosity signified the importance of dilute polymeric fluids for microfluidic application. The isolated arrangement of polymeric coils in dilute polymeric solutions assist independent molecular movement, which in turn support their deformation under high shear flows. The FENE- P drop model used in the present study, at higher solvent viscosity exhibit faster stress relaxation and remarkable elastic recovery in the expansion zone of the microchannel. The present numerical study can give significant insight into the cell squeezing inside microcapillaries. The dilute FENE-P viscoelastic fluid can also be considered as a significant model to predict the viscoelastic behaviour of useful polymeric fluids like hydrogels, paints and vesicles etc. Besides, the FENE-P model also possess shear thinning behaviour which can be applied to model drug carriers that are used in injectable form for the targeted drug delivery system in cancer theranostics.

Numerical Study of Deformation of Viscoelastic Drop Migrating Through Microchannel With Sudden Constriction

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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