Introduction to Pressure in Fluid Mechanics

Pressure Terminology
There are three different kinds of pressure reported in the literature, and it is important to know the terminology:

Equations for pressure distribution in a fluid

  • Consider a small fluid element of dimensions dx, dy, and dz as a free body diagram, on which all forces acting on the element will be discussed.
  • There are three kinds of forces important to fluid mechanics: gravity (body force), pressure forces, and viscous forces (due to friction). Gravity force,

    is shown in the sketch. Note the convention that gravity acts in the minus z direction.