Numerical treatment of electrical properties in two-phase electrohydrodynamic systems

Zupan, Bor (author), Zahoor, Rizwan (author), Bajt, Saša (author), Šarler, Božidar (author)

Generation and manipulation of micrometer-sized liquid jets is highly relevant for applications like sample delivery in serial femtosecond crystallography. A promising method combines gas flow focusing with electrospraying but remains underexplored due to numerical limitations regarding high interfacial electric property gradients. This study addresses this challenge by assessing different approaches for electrohydrodynamic (EHD) numerical treatment of two-phase interfaces within the finite volume method and the volume-of-fluid framework. A new geometric mean interpolation technique was developed to address the limitations of high electric conductivity-ratio gas–liquid systems. The technique was related to the established EHD modeling approaches, comprising two electric force implementations and two electric property interpolation methods. Three verification tests involving no flow conditions demonstrated consistent performance of all solvers regarding the electric equations, and they were charge-conservative. Validation on a free boundary problem experiment revealed varying levels of agreement. Results show that the Coulomb-polarization force implementation combined with weighted harmonic mean interpolation provides the most accurate and physically consistent modeling of electric forces at fluid interfaces, followed by the novel geometric mean technique. The model based on the Coulomb-polarization force is applied to simulate electro-flow-focused jets, capturing the complex interplay of hydrodynamic and electrostatic forces in a high-velocity co-flow configuration. While weighted harmonic mean interpolation yields the highest fidelity regarding the electric force magnitude and electric charge position, it fails for extremely low gas conductivities. The proposed geometric mean interpolation provides a stable alternative for simulating EHD two-phase flows, particularly in configurations with large interfacial electric property gradients.

• Language: English
• Keywords: electrohydrodynamic systems, electrical properties, finite volume methods, computational fluid dynamics
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2025
• Number of pages: 19 str.
• Numbering: Vol. 37, iss. 8, art. 083353
• PID: 20.500.12556/RUL-171190
• UDC: 532.5:519.6
• ISSN on article: 1070-6631
• DOI: 10.1063/5.0281409
• COBISS.SI-ID: 245855235
• Publication date in RUL: 18.08.2025

Record is a part of a journal

• Title: Physics of fluids
• Shortened title: Phys. fluids
• Publisher: American Institute of Physics
• ISSN: 1070-6631
• COBISS.SI-ID: 37828865

Secondary language

• Language: Slovenian
• Keywords: elektrohidrodinamični sistemi, električne lastnosti, metoda končnih elementov, računska dinamika tekočin