N. Tofighi, M. Ozbulut, A. Suleman, J. J. Feng & M. Yildiz
Euro. J. Mech. B Fluids 78, 194-202 (2019).
Abstract - A two-dimensional incompressible smoothed particle hydrodynamics scheme is used to simulate the interaction of micron-sized particles suspended in quiescent medium. A uniform electric field is applied to the particles, causing them to approach one another due to dielectrophoretic forces and form a chain. Both fluid and particles are assumed to be polarizable and non-conductive where the permittivity of the fluid is assumed to be lower than that of the particles. The numerical scheme is validated by comparing its predictions for simpler case of a pair of particles with results available in the literature. The effects of initial orientation, Reynolds number and differences in particle permittivity on the chaining behavior are studied afterwards. The results show that the particles may follow a convergent or divergent-convergent trajectory, depending on the initial orientation of the particle pair with the electric field. Increasing the field intensity in low-Reynolds regime expedites the chaining process without affecting the particle trajectory. However, the particles may diverge at larger Reynolds numbers. Assigning different permittivity to particles skews the chaining position toward the particle with lower permittivity. Simulating the process for multiple particles results in longer chains branching and encompassing the entire computational domain, much like those observed in experiments.