Abstract
The extensional effective viscosity, , of a suspension of solid cylindrical fibers in a Newtonian liquid is measured from the gravitational stretching of a quasisteady jet. We vary the length-to-diameter aspect ratio of the fibers, , from to , and the particle volume fraction, , in the range . For low values of , the extensional viscosity is found to agree with Batchelor's model for the dilute regime, which assumes noninteracting fibers aligned with the stretching direction, but for higher concentrations, is found to increase much more strongly with increasing than predicted by available models assuming purely hydrodynamics interactions between the fibers. Additional experiments are performed on the breakup of an unstable capillary bridge for . Although the variability in the bridge shape and the deviation from a viscous Newtonian dynamics in the late stage of the breakup increase significantly with increasing , it is found that the mean total duration of the breakup is in good agreement with a Newtonian effective dynamics limited by the extensional viscosity, .
- Received 7 September 2020
- Accepted 29 March 2021
DOI:https://doi.org/10.1103/PhysRevFluids.6.044307
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