Navier–Stokes equations describe the motion of fluids; they arise from applying Newton’s second law of motion to a continuous function that represents fluid flow. If we apply the assumption that stress in the fluid is the sum of a pressure term and a diffusing viscous term, which is proportional to the gradient of velocity, we arrive at a set of equations that describe viscous flow. This handbook provides new research on the theories and applied analysis of Navier-Stokes Equations.