Capillary number

In fluid dynamics, the capillary number (Ca) represents the relative effect of viscous forces versus surface tension acting across an interface between a liquid and a gas, or between two immiscible liquids. For example, an air bubble in a liquid flow tends to be deformed by the friction of the liquid flow due to viscosity effects, but the surface tension forces tend to minimize the surface. The capillary number is defined as: where µ is the dynamic viscosity of the liquid, V is a characteristic velocity and is the surface or interfacial tension between the two fluid phases.

Capillary number

In fluid dynamics, the capillary number (Ca) represents the relative effect of viscous forces versus surface tension acting across an interface between a liquid and a gas, or between two immiscible liquids. For example, an air bubble in a liquid flow tends to be deformed by the friction of the liquid flow due to viscosity effects, but the surface tension forces tend to minimize the surface. The capillary number is defined as: where µ is the dynamic viscosity of the liquid, V is a characteristic velocity and is the surface or interfacial tension between the two fluid phases.