Water in Motion

Since nothing originates from nothing, conservation of mass provides the basic knowledge of both pressure and free surface flow as pioneered by Heron of Alexandria. Momentum and energy conservation describe the way water moves due to gravity as a result of Newton’s laws. Two flow regimes, laminar and turbulent, have two different ways in which water can move calmly or crazy. The Eulerian and Lagrangian approaches are two ways to observe and describe flowing water. The movement of water in natural water bodies and man-made infrastructures is explained by the basic understanding of pressure, open channel, and groundwater flows, but understanding water movement everywhere still requires a continual clash of concepts, experiments, and refutations.