Effect of Roughness on Wetting of Solids
Sessile Droplet Evaporation
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AbstractThe wetting of rough surfaces and the three-phase contact line are complex and vary according to the dimensions of the roughness and its spatial heterogeneity. The results documented in this thesis show that the apparent contact angle varies around the periphery of the water droplet due to the roughness of the surface on the first contact. Also, repeated wetting of the droplet on the surface reveals that the apparent contact angle changes due to residual liquid remaining on the rough surface. The wetting of water droplets is even more complex for curved rough surfaces. For these surfaces, at the three-phase contact line, the line tension contributes to the force balance. In this research, experiments reveal the effect of the roughness and curvature of a solid surface on the apparent contact angle as well as the line tension: the greater the roughness and the curvature of the solid, the larger is the line tension. Evaporation of sessile water droplets on solid surfaces has drawn much attention. Classic models do not describe evaporation near the three-phase contact line of rough surfaces. Here, we describe a new model for evaporation of sessile droplets on rough solid surfaces and compare the results to experimental results. The results suggest that the evaporation rate is larger on rougher surfaces. Electrokinetic phenomena which are founded on the physical mechanisms of streaming potential, zeta potential, electrical double layer (EDL) have an impact on rock wettability. If an electrolyte flows through porous rock, given the EDL and charge transport, potentially a current could occur in the system. In other words, given the existing salt concentration in reservoir water, there is potential that the moving liquid during production or water flooding or under natural flow could generate a current. Here, we report on experiments to explore the idea of the current generation from the flow of electrolytes through porous sandstone.
CitationHuang, X. (2021). Effect of Roughness on Wetting of Solids (Unpublished doctoral thesis). University of Calgary, Calgary, AB.
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