Sahithyan's S1 -- Fluid Mechanics
Statics
Terminology
Normal Forces
Forces acting perpendicular to the plane of a surface.
Shear Forces
Forces acting in the plane of a surface. When a fluid is at rest, no shear forces act on it.
Fluid
A fluid is defined as a substance which flows continuously under the action of shear forces no matter how small the forces may be.
Liquids and gasses are considered fluids. Unlike solids, fluids don’t show permanent resistance to deformation. Fluids are considered a continuum (continuously filled matter). Their bulk behaviour is considered when solving fluid mechanics problems.
Fluid Particle
Very small volume of fluid containing the point concerned.
Average values of properties for fluid particles are considered. Properties are assumed to vary gradually between particles.