The effect of a solid surface on the resistance of a three phase contact line to motion was investigated in silylated, cylindrical and horizontal glass capillaries. The solid surface wetting property was modified by silylation procedures and prewetting with water or dodecane. To compare the calculated and measured values of different pressure drops the linear flow velocity and the dynamic contact angles were measured as a function of the hydrostatic pressure difference (driving force). The wetting heterogeneity of capillary surfaces, caused by water-prewetting and different silylation procedures, was suggested to be responsible for the capillary pressure drop which could not be described by the Laplace term alone.
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