arXiv subjects

Andrew Sowinski

Publications and source records attributed to Andrew Sowinski.

3 recordsLinked to original sources

arXiv2026

The effect of discontinuous injection on particle back-flow in pneumatic conveying systems

Pneumatic conveying is used in many process industries to transport dry, granular, and powdered solids. The triboelectrification of particles during conveying causes particle agglomeration, spark discharges, and disruptions in particle flow, making particles move upstream against the fluid flow. The effect of frequency of particle injection on particle backflow is studied using CFD-DEM simulations. Conveying flow in a square-shaped duct with fluid frictional Reynold's number equal to 180, particle Stokes number equal to 8, and individual particle charge equal to 504 fC, is simulated with different particle injection frequencies. The proportion of particles moving upstream is found to increase as the delay period between injections increases, and the effect of the length of the injection period is minimal. Further, particles moving upstream are situated in low-drag zones at the corners of the duct where the electrostatic force dominates. In conclusion, the delay period between discontinuous injections plays a major role in particle backflow. The findings of the article are important for industrial processes with discontinuous injection of particles with a risk of particle accumulation within the conveying boundary.

physics.flu-dyn↗

arXiv2026

CFD study of particle back-flow in pneumatic conveying systems due to triboelectrification

In industrial plants, pneumatic conveying systems are often used to convey particles from one location to another. Surprisingly, in bench-scale experiments, clusters of particles sometimes flow backward or upstream in the conveying channel. In this paper, the effect of electrostatic charge and forces on particle back-flow was investigated. Different conveying conditions with varying particle charges were simulated using computational fluid dynamics (CFD), and the resulting flow patterns were compared with CFD simulations of uncharged particles. In a channel flow with periodic boundary conditions in the streamwise and spanwise directions, it was found that electrostatic forces drive particles into low-velocity regions but do not reverse their flow. When transporting particles through a finite-length duct, electrostatic forces cause particles to settle close to the duct's inlet. Finally, when particles were injected into the duct in a pulse, back-flow was observed once particles obtained a charge of 5.04 femto-coulombs or more. The electrostatic forces decelerated the particles at the tail of the pulse and ultimately reversed their direction, whereas the particles at the head of the pulse were accelerated. Thus, it was concluded that electrostatic forces can cause particle back-flow in pneumatic conveying systems if particles are fed discontinuously.

physics.flu-dyn↗

arXiv2025

A Novel Apparatus For Particle-Particle Single Contact Electrification Experiments

The experiment of a single contact between two sub-centimeter high-speed particles is often difficult to execute, especially if the collision must be physically and electrically isolated, as is the case for triboelectrification studies. Apparatuses designed for this type of experiment fall short of providing high-speed isolated collisions with a high probability of contact. In this article, we propose a novel apparatus that combines pneumatic conveying and acoustic levitation to provide an electrically and physically isolated, high impact speed collision between two sub-centimeter particles with a collision success rate of 93 %. We can control the pre-contact charge, material, and size of both particles, and the impact speed and angle. Test results show that charge transfer between two insulator particles is not solely driven by contact potential difference; it is a stochastic process that requires large datasets to resolve and understand. Our new apparatus can efficiently generate these datasets and provide new insights on the stochastic nature of charge transfer, and the effect of each of the collision parameters mentioned earlier on particle-particle charge transfer.

physics.ins-det↗