Some of the important properties of the fluid are: density or mass density of the fluid, specific weight or weight density of the fluid, specific volume of the fluid, specific gravity or relative density of the fluid, viscosity of the fluid and others. All these are discussed in this two-part series
Introduction
Fluid is the substance that has tendency to flow; it can be any liquid or gas. Fluid mechanics is the branch of science that deals with the study of behavior of fluids whether they are at rest or are moving.
Here are some important properties of fluids:
1) Density or Mass Density of fluid
Mass density or simply density of the fluid is defined as the ratio of the mass of fluid to its volume. Density of the fluid can also be defined as the mass per unit volume of the fluid. Density of the fluid is denoted by the symbol ρ (rho).
In SI system the unit of measurement of the mass of the fluid is kg and that of the volume of fluid is cubic meter m3. Thus the unit of measurement of density is kg/ cubic meter (kg/m3). The density of the liquids is considered to be constant with the temperature, but of the gases it changes with the temperature.
The density of water is considered to be 1000kg/m3 or 1gm/cm3 and it is standard for the measurement of the density of the other fluids.
2) Specific Weight or Weight Density of the fluid
The specific weight or the weight density of the fluid is defined as the ratio of the weight of the fluid to the volume of the fluid. The weight density of the fluid is also defined as the weight of the fluid per unit volume of the fluid. Weight density of the fluid is denoted by the symbol w.
In SI system the unit of measurement of the weight of the fluid is N (Newton) and that of volume is cubic meter m3, hence the unit of measurement of specific weight is N/m3 (Newton per meter cube).
The value of the specific density of water in SI unit is 9.81 x 1000 Newton/m3.
Reference
Book: Fluid Mechanics and Hydraulic Machines by Dr. R. K. Bansal
Fluid Mechanics, Applications and Properties of Fluids
This is the series of articles on fluids that describes important concepts of fluids like what is fluid, what is fluid mechanics, applications of fluids, properties of fluids etc. Some important properties of fluids are mass density, specific weight, specific volume, specific gravity, viscosity etc.