COMPRESSIBLE MODEL OF FLOW-FOCUSED MICRO-JETS IN AN ELECTRIC FIELD

Flow focusing is a widely used method for producing liquid microjets in applications ranging from structural biology to nanotechnology. Recent experimental and numerical studies have shown that applying an external electric field can further enhance jet stability and thinning, a concept often referred to as electro-flow-focusing. While the liquid phase is reasonably treated as incompressible, the surrounding gas undergoes significant expansion, which can influence jet dynamics through both mechanical and thermal effects. This work presents a compressible multiphase model that combines the two-phase Navier-Stokes equations with electrostatic forces derived from the Maxwell stress tensor. Gas compressibility is explicitly resolved, allowing the capture of cooling effects associated with expansion. Heating due to the Joule effect is also implemented. Liquid density, viscosity and surface tension are treated as temperature-dependent. The model is applied to flow-focused geometries representative of gas-dynamic virtual nozzles. We analyze how gas expansion influences the subcooling of the liquid jet, thereby modifying its behaviour under the combined action of viscous, capillary, and electrostatic stresses.