Water Flow in a Pipe

This model represents **Bernoulli's principle**. It is a seemingly counterintuitive statement about *how the speed of a fluid relates to the pressure of the fluid*. Bernoulli's principle says: *Within a horizontal flow of fluid, points of higher fluid speed will have less pressure than points of slower fluid speed*.



Within a horizontal water pipe with a changing diameter, regions where the water is moving fast will be **under less pressure than regions where the water is moving slow**. In everyday life there are many observations that can be successfully explained by application of Bernoulli's principle, even though no real fluid is entirely inviscid and a **small viscosity often has a large effect on the flow**.