Effect of time-dependent sinusoidal electric field on the onset of electroconvection in a viscoelastic fluid layer

TL;DR

This study investigates how time-dependent sinusoidal electric fields influence the onset of electroconvection in a viscoelastic fluid layer, revealing frequency-dependent stabilization and destabilization effects.

Contribution

It introduces a theoretical analysis of electric field modulation effects on electroconvection thresholds in viscoelastic fluids using an Oldroyd-B model.

Findings

Low-frequency electric field modulation destabilizes the fluid layer.

Moderate and high frequencies stabilize the system.

Stress relaxation parameter significantly affects stability behavior.

Abstract

Time-periodic electric field modulation of a viscoelastic dielectric fluid layer heated from below and cooled from above is examined using an Oldroyd-B type liquid. On the basis of small amplitudes of modulation, the regular perturbation method can be used to calculate the threshold for correction of the critical Rayleigh number. The dielectric constant is assumed to be a linear function of temperature. We show that electric field modulation frequency, electrical, Prandtl number, and viscoelastic parameters are related to the shift in the critical Rayleigh number and the possibility of subcritical convection for low-frequency modulation of the electric field. Rayleigh number, wavenumber, and frequency stability are determined based on free-free isothermal boundary conditions. The dielectrophoretic force is only destabilizing when an electrical field is modulated at a low frequency because it is associated with an unmodulated layer of dielectric fluid. As a result of the stress relaxation parameter in a sinusoidal electric field, the system is destabilized at low frequencies and stabilized at moderate and high frequencies. The effect of strain retardation on mechanical anisotropy is completely opposite. The stability characteristics are illustrated through graphs showing the numerical values of parameters.