Inertio-elastic parametric resonance between inertia-dominated and elasticity-dominated Taylor vortex flows in Boger fluids confined between two co-oscillating cylinders
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引用次数: 0
Abstract
A Floquet analysis describing the influence of inertia and elasticity on the dynamics of the viscoelastic flow of a model Boger fluid between two co-oscillating cylinders is presented. This model is approximated by the Oldroyd-B constitutive equation which describes the rheological behavior of highly elastic polymer melts diluted with a Newtonian solvant. A linear stability analysis is developed to predict the effect of both the polymer/solvant viscosity ratio and the polymer elasticity on the critical vortex flow conditions at the onset of instability. Special attention is devoted to emphasize the flow reversal of the system, which is used as an indicator to distinguish between inertia-dominated and elasticity-dominated instability modes. It is shown that the occurrence of purely inertial reversing and non-reversing flows, setting in the Newtonian case, moves towards the high frequency limit only when dealing with weakly elastic and highly diluted viscoelastic solutions. These instability modes are considered inertia-dominated and are completely suppressed by moderate values of elasticity. However, the low and moderate frequency limits are characterized by the appearance of new elasticity-dominated instability modes that persist over the entire frequency range when highly elastic solutions are considered. In addition, it turns out that with slowly oscillating cylinders a purely elastic destabilizing mechanism is noticed and becomes inertio-elastic by increasing the oscillation frequency. These results provide comprehensive insights into the dynamics of oscillatory flows in pure and dilute polymeric substances.
期刊介绍：
The Journal of Non-Newtonian Fluid Mechanics publishes research on flowing soft matter systems. Submissions in all areas of flowing complex fluids are welcomed, including polymer melts and solutions, suspensions, colloids, surfactant solutions, biological fluids, gels, liquid crystals and granular materials. Flow problems relevant to microfluidics, lab-on-a-chip, nanofluidics, biological flows, geophysical flows, industrial processes and other applications are of interest.
Subjects considered suitable for the journal include the following (not necessarily in order of importance):
Theoretical, computational and experimental studies of naturally or technologically relevant flow problems where the non-Newtonian nature of the fluid is important in determining the character of the flow. We seek in particular studies that lend mechanistic insight into flow behavior in complex fluids or highlight flow phenomena unique to complex fluids. Examples include
Instabilities, unsteady and turbulent or chaotic flow characteristics in non-Newtonian fluids,
Multiphase flows involving complex fluids,
Problems involving transport phenomena such as heat and mass transfer and mixing, to the extent that the non-Newtonian flow behavior is central to the transport phenomena,
Novel flow situations that suggest the need for further theoretical study,
Practical situations of flow that are in need of systematic theoretical and experimental research. Such issues and developments commonly arise, for example, in the polymer processing, petroleum, pharmaceutical, biomedical and consumer product industries.
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