Selective withdrawal of polymer solutions: Experiments

Selective withdrawal of polymer solutions: Computations

“…This allows us to improve the maximum Deborah number De from 4.1 to above 50. This is still below some of the experimental values of Zhou and Feng [2], and will pose some inconvenience in comparing the two.…”

“…The polymer solutions used in the experiments are dilute [2]. Thus, we have used the Oldroyd-B and Giesekus models for their rheology.…”

“…Viewing this as an interesting process that couples interfacial deformation and bulk rheology, we have carried out concerted experimental and computational studies of selective withdrawal in an air-liquid system, with Newtonian and polymeric liquids. The experimental results, using silicone oils and dilute polymer solutions, are reported in the accompanying paper [2]. The main findings are: (a) the interfacial curvature is much greater for the polymer solutions than for a Newtonian one under comparable conditions, but the deformation is spatially more localized; (b) the surface of the polymer solutions ruptures at a critical flow rate, when a cusp forms directly above the suction tube from which a micron-sized air jet emanates toward the tube.…”

“…We have speculated in [2] that these differences arise from the viscoelastic stresses near the tip of the interface, where the polymer solution experiences elongational flow. We further speculated that this device may be used as an elongational rheometer if operated in the subcritical state.…”

“…From the balance between these forces, one can back out the extensional viscosity [11][12][13]. A commercial version of CTER, known as CaBER, has been widely used in recent years [2,[14][15][16]. Compared with FiSER, CTER can handle fluids with relatively low viscosity.…”