Further Reading

Here we consider only the relevant properties of fluids for our purposes. Find out about surface tension and capillary action elsewhere. Note that capillary action only features in pipes of ≤ 10 mm diameter.

Mass Density

Specific Weight

Relative Density (Specific Gravity)

A dimensionless measure of the density of a substance with reference to the density of some standard substance, usually water at 4°C:

Bulk Modulus

In analogy with solids, the bulk modulus is the modulus of elasticity for a fluid. It is the ratio of the change in unit pressure to the corresponding volume change per unit volume, expressed as:

Viscosity

The viscosity of a fluid determines the amount of resistance to shear force. Viscosities of liquids decrease as temperature increases and are usually not affected by pressure changes. From Newton’s Law of Viscosity: