Rayleigh–Taylor instability in leaky and perfect dielectric fluids under external electric fields by lattice Boltzmann method
Year: 2026
Type: article
Abstract: In this study, we present a lattice Boltzmann (LB) framework for electrohydrodynamic Rayleigh–Taylor instability (RTI-EHD) in Newtonian two-fluid systems treated as leaky or perfect dielectrics. The solver, implemented in the open-source parallel CooLBM code, couples a Cahn-Hilliard phase-field interface (He-Chen-Zhang model) with an incompressible LB flow solver, including consistent body forces, electric potential computation, and Maxwell stresses. The framework is validated against canonical problems, including single-phase charge relaxation, two-layer planar systems under uniform fields, droplet deformation in electric fields, and RTI without electric forcing. We then investigate RTI-EHD under horizontal and vertical electric fields for single- and multi-mode perturbations, examining the roles of field orientation, initial perturbation characteristics, and fluid electrical properties. In leaky-dielectric systems, the electric field can either suppress or enhance instability depending on contrasts in electrical properties. A key contribution is the fully LB-based RTI-EHD formulation. We also recover the analytical result that the leaky dielectric model reduces to the perfect dielectric limit when conductivity and permittivity ratios are equal, enabling both regimes to be simulated within a unified framework. In the perfect dielectric case, horizontal fields stabilize the interface more strongly for small perturbations, while vertical fields promote instability. The code is openly available at: https://gitlab.coria-cfd.fr/lbm/coolbm-rti-ehd .
Language: English
Subfield: Computational Mechanics
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,590
OpenAlex ID: W7164192267