Capillary pressure results from interactions of forces acting within and between fluids and their bounding solids. These include both ''cohesive'' forces (surface and interfacial tension) and ''adhesive'' (liquid-solid) forces. When adhesive forces are greater than cohesive forces, the liquid is said to be ''wetting'' ([[:File:charles-l-vavra-john-g-kaldi-robert-m-sneider_capillary-pressure_1.jpg|Figure 1a]]). When cohesive forces exceed adhesive forces, the liquid is ''nonwetting'' ([[:File:charles-l-vavra-john-g-kaldi-robert-m-sneider_capillary-pressure_1.jpg|Figure 1b]]). The relative [[wettability]] of the fluids is described by the ''contact angle'' (θ), which is the angle between the solid and the fluid-fluid interface as measured through the denser fluid ([[:File:charles-l-vavra-john-g-kaldi-robert-m-sneider_capillary-pressure_1.jpg|Figure 1]]). | Capillary pressure results from interactions of forces acting within and between fluids and their bounding solids. These include both ''cohesive'' forces (surface and interfacial tension) and ''adhesive'' (liquid-solid) forces. When adhesive forces are greater than cohesive forces, the liquid is said to be ''wetting'' ([[:File:charles-l-vavra-john-g-kaldi-robert-m-sneider_capillary-pressure_1.jpg|Figure 1a]]). When cohesive forces exceed adhesive forces, the liquid is ''nonwetting'' ([[:File:charles-l-vavra-john-g-kaldi-robert-m-sneider_capillary-pressure_1.jpg|Figure 1b]]). The relative [[wettability]] of the fluids is described by the ''contact angle'' (θ), which is the angle between the solid and the fluid-fluid interface as measured through the denser fluid ([[:File:charles-l-vavra-john-g-kaldi-robert-m-sneider_capillary-pressure_1.jpg|Figure 1]]). |