Fluid Statics

Fluid statics deals with problems associated with fluids at rest. The fluid can be either a liquid or a gas. In the study of fluids in static equilibrium, the significant forces acting on a fluid element include those due to gravity, F_G = Mg = W = γV and pressure, F_p = ΔpA. Additionally, other potentially significant forces for fluid statics may include those due to elasticity, F_E = E_vA (compressible fluids) and surface tension, F_T = σL (droplets, bubbles, thin films, and capillarity). However, the viscous force, F_v = τA = μ dv/dy does not exist in a fluid in static equilibrium, regardless of the fluid viscosity, μ, and the inertia force, F_I = Ma = ρv ² L ² does not come into play in fluid statics. In order for a fluid element to be in static equilibrium (at rest), the sum of all of the external forces must be zero, as given by Newton's second law of motion, ΣF = 0. Fluid statics applies the principles of hydrostatics, which are based on Pascal's law and Newton's second law of motion. Furthermore, while hydrostatic fluid pressure exists in both fluid statics and in fluid flow (fluid dynamics) situations, Chapter 2 introduces the topic of fluid pressure for fluids in static equilibrium, while Chapter 4 and Chapter 5 introduce the topic of fluid pressure for fluids in motion.