This section will discuss capillary bridges in more detail. Capillary bridges are formed under the influence of capillary action, which will be discussed first. Also the forces caused by capillarity are briefly discussed. Next, the characteristics of the particles and their effect on the shape of the bridge are discussed. This is followed by the mechanism of capillary bridge breakup. Finally the process of capillary bridge formation by condensation is discussed.
2.1.1. CAPILLARY ACTION
Liquids are able to flow opposite to the direction expected from gravity; this is caused by the capillary action.
Capillary action arises from a combination of surface tension and adhesive forces between the liquid and the solid. The difference in intermolecular attraction in the liquid and adhesion …show more content…
First, the primary neck decreases is size (1-2). During secondary necking (3), the pressure in the mid-plane builds and two local minima move away from the center (4). Eventually, the capillary bridge is completely pinched off fromthe water film(5). When the capillary bridge breaks (6) a satellite droplet is formed and the water films start to spread evenly along the surface. Adapted from [Y.-J.
Chen and P. H. Steen, Dynamics of inviscid capillary breakup: collapse and pinchoff of a film bridge, Journal of FluidMechanics 341, 245
(1997).]
formed, which grows by flow through the water film and capillary condensation. Eventually, an equilibrium size is reached and the bridge stops growing. Due to external forces the capillary bridge will shrink and break.
The mechanism of formation and breakup of a capillary bridge between two spherical particles by both flow and condensation is shown in Figure 2.3. An approximate expression for the change of the radius of curvature of a liquid meniscus between a sphere and a plate, based on water condensation only, was derived by
Kohonen,Maeda and Christenson [25]. This expression is generalized by Butt and Kappl [5] (2.4): dr dt
Æ
DdMW P0
½RTR¤
2.1.1. CAPILLARY ACTION
Liquids are able to flow opposite to the direction expected from gravity; this is caused by the capillary action.
Capillary action arises from a combination of surface tension and adhesive forces between the liquid and the solid. The difference in intermolecular attraction in the liquid and adhesion …show more content…
First, the primary neck decreases is size (1-2). During secondary necking (3), the pressure in the mid-plane builds and two local minima move away from the center (4). Eventually, the capillary bridge is completely pinched off fromthe water film(5). When the capillary bridge breaks (6) a satellite droplet is formed and the water films start to spread evenly along the surface. Adapted from [Y.-J.
Chen and P. H. Steen, Dynamics of inviscid capillary breakup: collapse and pinchoff of a film bridge, Journal of FluidMechanics 341, 245
(1997).]
formed, which grows by flow through the water film and capillary condensation. Eventually, an equilibrium size is reached and the bridge stops growing. Due to external forces the capillary bridge will shrink and break.
The mechanism of formation and breakup of a capillary bridge between two spherical particles by both flow and condensation is shown in Figure 2.3. An approximate expression for the change of the radius of curvature of a liquid meniscus between a sphere and a plate, based on water condensation only, was derived by
Kohonen,Maeda and Christenson [25]. This expression is generalized by Butt and Kappl [5] (2.4): dr dt
Æ
DdMW P0
½RTR¤