Capillary Entry Flow of Mobile Viscoelastic Fluid: Analysis Based on Boundary Layer Approximation and its Experimental Verification

Observation of visualized flow of capillary entry flow of a mobile viscoelastic polymer solution, PAA/W, shows that the appearance of inflow region is quite similar to a Newtonian jet, and influence of the reservoir bottom where the capillary is attached is insignificant as the case of the nozzle wall on the Newtonian jet. The boundary layer approximation is applied to the viscoelastic capillary entry flow in analogy with the Newtonian jet, in order to give a method to predict the contour and growth of inflow region length Lδ. Uni-axial elongational viscosity is estimated by comparing the analytical result of Lδ with the experimental values in steady flow. Prediction of the length and contour of inflow region of PAA/W by the analytical method is shown to agree well with experimental observation.