👉 The hanging fluid, also known as a droplet or meniscus, refers to the curved surface of a liquid that forms when it is supported by the walls of a container, typically at the liquid-air interface. This phenomenon occurs because surface tension causes the molecules at the liquid's surface to attract each other more strongly than they do with the surrounding air, creating a concave shape. The curvature of the meniscus depends on factors like the liquid's properties (such as surface tension and viscosity) and the container's shape. For instance, in a capillary tube, the meniscus bends upward due to adhesive forces between the liquid and the tube walls, while in a flat container, it tends to form a concave curve. The hanging fluid is crucial in various applications, including capillary action, wetting, and the design of microfluidic devices.
