Impact of seeding particle properties on PIV accuracy in electrohydrodynamic systems

Abstract

Particle Image Velocimetry (PIV) is a widely utilized technique for visualizing fluid flows, enabling the capture of instantaneous velocity fields with a single measurement. This method requires introducing fine tracer particles into the fluid, illuminating them with a laser source, and recording their motion to determine the velocity distribution. However, in electrohydrodynamic (EHD) systems, the use of these particles introduces challenges due to their interaction with the applied electric field. A key concern is the accumulation of electric charges on particle surfaces, potentially altering the electric field distribution. Charged particles may travel at different velocities from the surrounding fluid, violating the fundamental PIV assumption that particles accurately track fluid motion. Additional issues include particle clumping, filament formation, or adhesion to solid surfaces, which hinder charge transfer in the liquid. Ultimately, particles may absorb all available charges, neutralizing the fluid and reducing its motion. These effects depend strongly on the fluid type and tracer particles used.

In this study, five particle types were examined: PMMA (polymethyl methacrylate), POM (polyoxymethylene), PTFE (polytetrafluoroethylene), SiO₂ (silicon dioxide), and Vestosint (polyamide powder). Experiments were conducted on a hydrofluoroether dielectric liquid (HFE-7100) in a symmetric cylinder-to-cylinder configuration with a DC voltage applied between electrodes. Repeatability of PIV measurements was evaluated across multiple runs. Particle migration velocity relative to the fluid was analyzed to assess their influence on measurement accuracy. Results showed significant variation in fluid behavior depending on particle type, highlighting the critical role of seeding particle properties in ensuring accurate PIV measurements in EHD systems.