Capillary Rise or Fall of Liquids

The behavior of liquids in narrow tubes is one of the most common examples in which capillary forces are involved. It will be shown later how important this phenomenon is in many different parts of everyday life and technology. In fact, liquid curvature is one of the most important physical surface properties that requires attention in most of the application areas of this science. The range of these applications is from blood flow in the veins to oil recovery in the reservoir. Properties of fabrics are also governed by capillary forces (i.e., wetting, etc.). The sponge absorbs water or other fluids where the capillary forces push the fluid into the many pores of the sponge. This is also called wicking process (as in candlewicks). 

FIGURE 2.8 Rise of liquid in a glass capillary (a) of water, (b) fall of Hg. 

If the radius of the capillary is larger than 0.5 mm, then one will need corrections for accurate measurements. Tables for such corrections are published in the current literature (Adamson and Gast, 1997). This phenomenon is of importance for plants with very high stems in which water is needed for growth. However, in some 

Similar results can also be derived by using the Laplace equation (Equation 2.21) (1/radius = 1/R)  

The liquid rises to a height h and the system achieves equilibrium, and the following relation is found  

---

Capillary Rise (or Fall) of Liquids (Capillary Forces)... 

---