Spatiotemporal Transitions of Deposition Nucleation Sites in Fully Developed Turbulent Flow

In familiar applications, including engine fouling problems and in dust filtration technologies, electrostatic charges naturally accumulate on particles due to tribocharging. In multiphase flow, charged particles stick to a non-conducting surface during fully developed turbulent flow. This study investigates changes in the growth rate of nucleation sites as charged particles are preferentially deposited on a surface over time. Experiments were conducted in a vertical turbulence channel to observe charged particle deposition dynamics. It was observed that electrostatic and turbophoresis effects work synergistically and antagonistically to induce particle adhesion to the wall. Individual deposits were not stochastic, but rather formed characteristically distinct patterns at preferred nucleation sites. Preliminary results show that not only do deposit locations vary in their geometric profiles, i.e. their morphologies, but they also vary in spatiotemporal complexity. In the several growth phases that characterized the nucleation sites, it was observed that the leading edge grows and typically outpaces the erosion of the trailing edge, both taking place vertically against the direction of the flow. It is this overall growth rate that is the subject of this investigation.