The rheology of a bubbly liquid
By E. Llewellin, H. Mader, S. Wilson. Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences, 2001
209 citations recorded by the source corpus.
A semiempirical constitutive model for the visco-elastic rheology of bubble suspensions with gas volume fractions φ < 0.5 and small deformations (Ca ≪ 1) is developed. The model has its theoretical foundation in a physical analysis of dilute emulsions. The constitutive equation takes the form of a linear Jeffreys model involving observable material parameters: the viscosity of the continuous phase, gas volume fraction, the relaxation time, bubble size distribution and an empirically determined dimensionless constant. The model is validated against observations of the deformation of suspensions of nitrogen bubbles in a Newtonian liquid (golden syrup) subjected to forced oscillations. The effect of φ and frequency of oscillation f on the elastic and viscous components of the deformation are investigated. At low f, increasing φ leads to an increase in viscosity, whereas, at high f, viscosity decreases as φ increases. This behaviour can be understood in terms of bubble deformation rates and we propose a dimensionless quantity, the dynamic capillary number Cd, as the parameter which controls the behaviour of the system. Previously published constitutive equations and observations of the rheology of bubble suspensions are reviewed. Hitherto apparently contradictory findings can be explained as a result of Cd regime. A method for dealing with polydisperse bubble size distributions is also presented.
Subfields: Fluid Flow and Transfer Processes, Materials Chemistry
View Paper: https://www.semanticscholar.org/paper/057c9e3ba1334ed966fc717831d28be489f96c1f
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In Fluid Flow and Transfer Processes
In Materials Chemistry
Citations in the corpus
- Effects of bubble deformation on the viscosity of dilute suspensions (2002, methodology): “The complementary problem for unsteady flows was recently studied experimentally by Llewellin et al. [ 7 ] for Ca � 1 and oscillatory flows.”
- Forecasting volcanic eruptions (2003, background): “Magma rheology is greatly complicated by the presence of suspended crystals and gas bubbles [42,43], particularly at high concentrations where rheology becomes strongly non-Newtonian.”
- Gas migration regimes and outgassing in particle-rich suspensions (2015, unknown): “The syrup is Newtonian with a viscosity of ∼60 Pa s at 20C and surface tension of ∼80 mN/m [27].”