Exploring the fluid dynamics of highly charged dielectric liquids

• Applicant: Professor Dr. Steffen Hardt
• Subject Area: Fluid Mechanics
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 576560918

This proposal addresses the injection of charges into dielectric liquids and their subsequent spreading inside the liquid phase. Dielectric liquids (as opposed to electrolytes such as water) have a very low density of native charges, which is why phenomena such as electroosmotic flow are usually not observed in dielectric liquids. In the proposed project, a method to introduce charges into dielectric liquids will be implemented that utilizes the principle of immersed electrospray, that is, the injection of charged droplets of an electrolyte. This should allow introducing charge densities larger than those characteristic for existing methods, which is to be confirmed based on experiments. Parameter studies where the operating parameters and the types of liquids are varied will help identifying optimal configurations for charge injection. Apart from that, experiments on droplet-wall interactions and with charged liquid jets will be performed. The theoretical/numerical part of the proposed project aims at studying the spreading of the suspended charges inside the liquid. Two corresponding scenarios will be studied: A charged liquid completely filling a channel and a charged jet surrounded by a sheath flow. The corresponding numerical model is based on the coupled Poisson, Nernst-Planck and Stokes equations.

• DFG Programme: Research Grants