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Convective and absolute instabilities in electrohydrodynamic flow for viscoelastic fluid
Zhenze Yao1, Mengqi Zhang2, Jian Wu1
1Harbin Institute of Technology, School of Energy Science and Engineering, Harbin, Heilongjiang, People's Republic of China.
Physical Review. E
|August 19, 2025
Summary
This study investigates instabilities in viscoelastic fluids under electrohydrodynamic-Poiseuille flow. Increased shear strength generally stabilizes the flow, but high elasticity can lead to upstream-propagating waves.
Area of Science:
- Fluid Dynamics
- Non-Newtonian Fluid Mechanics
- Electrohydrodynamics
Background:
- Viscoelastic fluids exhibit complex behaviors under combined flow and electric fields.
- Understanding instabilities is crucial for controlling convective and absolute phenomena.
Purpose of the Study:
- To analyze convective and absolute instabilities in electrohydrodynamic-Poiseuille mixed convection of Oldroyd-B viscoelastic fluids.
- To differentiate between weakly and strongly elastic fluid behaviors based on instability onset.
- To investigate the influence of Poiseuille flow shear strength and polymer concentration on instability characteristics.
Main Methods:
- Analysis of stationary and oscillatory characteristics at convection onset.
- Mathematical modeling using the Oldroyd-B viscoelastic fluid model.
- Kinetic energy budget analysis to understand destabilizing/stabilizing factors.
Main Results:
- Distinguished weakly (viscosity-dominated) and strongly (elasticity-dominated) elastic fluids.
- Found that increased shear strength raises instability thresholds.
- Observed downstream-propagating transverse rolls (TRs) at low concentrations, but upstream-propagating TRs at high concentrations and elasticity.
- Identified energy transfer from electric field gradients as a destabilizing factor in strongly elastic fluids.
Conclusions:
- Poiseuille flow shear strength and fluid elasticity significantly alter instability modes and thresholds.
- Polymeric stresses have a dual role in suppressing or enhancing instability depending on flow regime.
- Electric field gradient energy transfer is a key destabilizing mechanism in highly elastic fluids.
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