The fluids for which the rate of deformation is proportional to the shear stress are called Newtonian fluids and the linear relationship for a one-dimensional system is shown in Fig. The property that represents the internal resistance of a fluid to motion (i.e.
The situation is similar when a fluid moves relative to a solid or when two fluids move relative to each other. Viscosity ( u): When two solid bodies in contact, move relative to each other, a friction force develops at the contact surface in the direction opposite to motion. In SI system, the temperature is expressed in terms of absolute value in Kelvin scale (K =☌+ 273).Ĥ. Many a times, the temperature is expressed in centigrade scale (☌) where the freezing and boiling point of water is taken as 0☌ and 100☌, respectively. In thermodynamic sense, it is the measure of internal energy of a system. Temperature ( T): It is the measure of hotness and coldness of a system. Many a times the reciprocal of mass density is called as specific volume. The standard values for density of water and air are given as 1000kg/m 3 and 1.2 kg/m 3, respectively. The units and dimensions are given as,įor mass density Dimension: ML -3 Unit: kg/m 3įor specific weight Dimension: ML -2 T -2 Unit: N/m 3 It is expressed in three different ways mass density, specific weight ( ρg) and relative density/specific gravity. Density: The density of a substance is the quantity of matter contained in unit volume of the substance. A material requiring a shear stress of one dyne per square centimeter to produce a shear rate of. In SI system the unit and dimension of pressure can be written as, N/m 2 and ML -1 T -2, respectively.Ģ. The fundamental unit of viscosity measurement is the poise. More details will be available in the subsequent section (Lecture 02). Pressure ( p): It is the normal force exerted by a fluid per unit area. Most common properties of the fluid are:ġ. The number of properties required to fix the state of the system is given by state postulates. The state of a system is described by its properties. It may either be intensive (mass independent) or extensive (that depends on size of system).
Any characteristic of a system is called property.