👉 A hollow fluid, also known as a gas or liquid in a confined space, is a substance where the volume is not completely filled by its molecules. Instead, it occupies the entire space between the walls of a container, creating a void inside. This phenomenon is distinct from a solid, where molecules are tightly packed and the material has a definite shape and volume. In a hollow fluid, the pressure inside can differ from the external pressure, leading to unique behaviors like surface tension and capillary action. These properties make hollow fluids crucial in various applications, from lubrication to medical devices and microfluidics.
