What is the role of surface tension in fluid flow?

Surface tension affects fluid flow by creating a resistance to deformation at the surface.

Surface tension is a property of liquids that arises due to the cohesive forces between the molecules at the surface. This cohesive force creates a resistance to deformation at the surface, which can affect fluid flow. For example, when a liquid is flowing through a narrow channel, the surface tension can cause the liquid to form a meniscus at the edges of the channel. This can lead to a change in the pressure distribution across the channel, which can affect the flow rate.

Surface tension can also affect the behaviour of fluids in capillary tubes. Capillary action occurs when a liquid rises up a narrow tube due to the surface tension forces. This can be seen in plants, where water is transported from the roots to the leaves through capillary action. The surface tension forces can also cause the liquid to form droplets, which can affect the flow rate and direction of the fluid.

In addition, surface tension can affect the stability of fluid interfaces. For example, in the case of two immiscible liquids, such as oil and water, the surface tension forces can cause the liquids to form distinct interfaces. This can affect the flow behaviour of the liquids, as well as their mixing and separation.

Overall, surface tension plays an important role in fluid flow, affecting the behaviour of liquids in a variety of ways. Understanding the effects of surface tension is important for a range of applications, from industrial processes to biological systems.