Forces on Fluid Elements
Fluid Elements - Definition:
Fluid element can be defined as an infinitesimal region of the fluid continuum in isolation from its surroundings.
Two types of forces exist on fluid elements- Body Force: distributed over the entire mass or volume of the element. It is usually expressed per unit mass of the element or medium upon which the forces act.
Example: Gravitational Force, Electromagnetic force fields etc. - Surface Force: Forces exerted on the fluid element by its surroundings through direct contact at the surface.
Surface force has two components:- Normal Force: along the normal to the area
- Shear Force: along the plane of the area.
The shear force is zero for any fluid element at rest and hence the only surface force on a fluid element is the normal component.
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