This paper presents a combined stability analysis and numerical investigation of Rayleigh-Bénard convection in a planar dielectric liquid layer subjected to the simultaneous action of Coulomb and buoyancy forces. For the first time, Rayleigh-Bénard convective instability with electric conduction is considered. Fully coupled set of governing equations for fluid flow, heat transfer, and electrostatics are solved using the finite-volume method (FVM) framework of OpenFOAM. The fluid layer is destabilized under the combined action of buoyancy and Coulomb forces. Rayleigh number $\left(\text{Ra}\right)$ and the Conduction number $\left(C_0\right)$ are the control parameters for fluid flow. Distributions of physical variables in the hydrostatic state are derived. Modal stability analysis is performed to establish the neutral stability curve in the $\text{Ra}\text{−}{C}_0$ plane. Present numerical results are compared with the results of stability analysis. The flow and heat transfer characteristics in the $\text{Ra}\text{−}{C}_0$ parameter space are analyzed. The present study provides deeper insights into the electro-thermo-convective flow mechanism due to the EHD conduction phenomenon occurring at weak and medium electric fields. The results of this study can serve as a benchmark to design flow systems subjected to combined gradients of thermal and electric fields.

• Received 31 May 2023
• Accepted 8 November 2023

DOI:https://doi.org/10.1103/PhysRevFluids.9.013902