Numerical investigation revealing droplet electrohydrodynamic response on hydrophobic substrate

This study investigates the dynamics of conducting droplets impacting hydrophobic substrates under externally applied electric fields using high-fidelity numerical simulations. A modified OpenFOAM solver is developed that integrates Kistler’s dynamic contact angle model with a coupled electrohydrodynamic module to capture the combined effects of inertia, surface tension, viscosity and Maxwell stresses. Validation against experimental data confirmed that the solver reproduces inertia-capillary oscillations and spread–recoil behavior with good accuracy. The simulations reveal that electric fields change the energy distribution of an impacting droplet. Increasing electric Bond number reduces lateral spreading, delays recoil and enhances vertical elongation, producing rebound even on hydrophobic substrates that normally suppress it. At B o e = 0 . 25 the maximum rebound height increases by nearly fifty percent compared to the case without electric field, demonstrating the strong role of Maxwell stresses. Analysis of flow fields and interfacial distributions shows that this behavior is due to decrease in curvature-driven pressure gradients, increase in tangential velocities and distribution of surface electrical charge. Regression-based correlations are derived to quantify equilibrium rise and spread, damping ratios and oscillation frequencies as functions of B o e , W e and θ E . These predictive laws reproduce simulations consistently below margin of error, confirming their usefulness as surrogates for droplet electrohydrodynamics. • Electric fields redistribute droplet energy between spread and rebound. • Increasing Boe suppresses lateral spread and enhances vertical elongation. • Oscillator analogy explains field-induced changes in stiffness and damping. • Findings enable rapid design of electrohydrodynamic droplet control.