Journal of Physical Studies 27(1), Article 1401 [8 pages] (2023) DOI: https://doi.org/10.30970/jps.27.1401 ONSET OF ELECTROCONVECTION IN A COMPACTLY PACKED DIELECTRIC LIQUID-PERMEABLE LAYER WITH A MODULATED ELECTRIC FIELD C. Rudresha , C. Balaji , V. Vidya Shree , S. Maruthamanikandan  Department of Mathematics, Presidency University, Bengaluru, Karnataka, India–560064, e-mails: rudresha.c@presidencyuniversity.in, maruthamanikandan@presidencyuniversity.in Received 20 September 2022; in final form 14 November 2022; accepted 26 December 2022; published online 04 March 2023

The effect of time-periodic electric field modulation on electroconvection in a compactly packed dielectric liquid-permeable layer is investigated using the small perturbation method coupled with the regular perturbation method. The dielectric constant is assumed to be a linear function of temperature. For small amplitude electric field modulation, the critical correction Rayleigh number is determinedusing the regular perturbation method. The critical Rayleigh number is obtained in terms of the electrical Rayleigh number, Vadasz number, normalized porosity, and the modulation frequency to determine the stability of the system. It is found that electric field modulation at low frequencies can create subcritical convective motion. The impact of Vadasz number is shown to be akin to that of the dielectrophoretic force. The stabilizing influence of normalized porosity is more pronounced when the frequency of electric field modulation is modest and large. The study reveals that time-varying electric fields and a densely packed porous layer may have implications for the control of electroconvection in heat transfer applications involving dielectric fluids as working media.

Key words: Darcy model, dielectric fluid, electric field, porous medium, porosity and modulation.

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