Force density

In fluid mechanics, the force density is a vector field representing the flux density of the hydrostatic force within the bulk of a fluid. Force density is represented by the symbol f, and given by the following equation, where P is the pressure:

<math>\mathbf{f} = \nabla P <math>.

The force on a differental volume element dV of the fluid is:

<math>d\mathbf{F} = \mathbf{f}dV<math>

Thus, the force density at a point in a fluid determines the acceleration of the fluid at that point.