What happens to the pressure of a fluid according to Bernoulli’s principle?

According to Bernoulli's principle, in a streamline flow of an incompressible fluid, the total mechanical energy of the fluid remains constant. This principle highlights the inverse relationship between the velocity of a fluid and its pressure. Specifically, as the velocity of the fluid increases, the pressure within that fluid decreases.

This phenomenon can be understood by recognizing that total energy is ascribed to three key components: fluid pressure energy, kinetic energy (due to the fluid's velocity), and potential energy (due to elevation). If the fluid is moving faster (higher velocity), it will have a greater share of kinetic energy, which means there is less energy available for pressure. Consequently, when fluid velocity increases, the pressure exerted by that fluid decreases.

This concept is frequently illustrated in various applications, such as in the design of airplane wings where the shape causes air to move faster over the top surface, resulting in lower pressure above the wing compared to below, thereby generating lift.