Flow electrification of dielectric liquids : modeling and numerical study

When a liquid is in contact with a solid surface, physico-chemical phenomena occur at the interface, leading to the formation of the electrical double layer. Inside the liquid, the electrical double layer comprises the Stern layer corresponding to a thin region adjacent to the solid/liquid interface, and the diffuse layer, whose the concentration of free ions decreases away from the Stern layer. Accordingly, flow electrification takes place when a flowing liquid, in contact with a solid, transports electric-charge carriers (ions) from the diffuse layer towards the bulk of the flow domain. This motion, in turn, generates a streaming current that is deemed responsible of major electrostatic accidents in the petrochemical industrial sector. Although studied extensively during the last 50 years, this phenomenon is currently not well understood, notably because of the inherent complexity of flow turbulence. Indeed, conclusive studies about the role of turbulence and the underpinning mechanisms of turbulent flow electrification are still lacking. Therefore, this thesis studies in detail the phenomenon of electrification of flowing dielectrics liquids, notably in turbulent channel flows.(SC - Sciences) -- UCL, 202