Fluid mechanics Unit one solved problems.pptx

Fluid mechanics notes

1. problems

2. Compressibility and bulk modulus

3. Surface tension and capillarity

4. Definition Density :-Density is simply mass per unit volume at standard temperature & pressure. Weight Density :It is defined as the weight per unit volume at standard temperature & pressure. Specific Gravity : Specific gravity is the ratio of the specific weight of the liquid to the specific weight of a standard fluid. Specific volume : specific volume of a fluid is define as the volume of a fluid occupied by a unit mass or volume per unit mass of a fluid is called specific volume. Viscosity : Viscosity is the resistance that a fluid offers to flow when subject to a shear. Kinematic viscosity – it is define as the ratio between the dynamic viscosity and density of fluid.

5. Definition Newton’s Law of Viscosity: This law states that the shear stress on a Fluid Element layer is directly proportional to the rate of Shear strain Vapour Pressure: Consider a liquid contained in a closed vessel, the vapour molecules gets accumulated in the space between the free surface & the top of vessel.This accumulated vapour of the liquid exerts a partial pressure on the liquid surface is known as Vapour Pressure i.e Mercury has very low vapour pressure (0.173 N/m²) and high density (13000 kg/m³)

6. Definition Compressibility and bulk modulus: Compressibility is the reciprocal of the bulk modulus of elasticity, K which is defined as the ratio of compressive stress to volumetric strain. Surface tension: Surface tension is defined as the tensile force acting on the surface of a liquid in contact with a gas or on the surface between two immiscible liquids such that the contact surface behaves like a membrane under tension.

7. Definition Capillarity is defined as a phenomenon of rise or fall of a liquid surface in a small tube relative to the adjacent general level of liquid when the tube is held vertically in the liquid. The rise of liquid surface is known as capillary rise while the fall of the liquid surface is known as capillary depression. It is expressed in terms of cm or mm of liquid. Its value depends upon the specific weight of the liquid, diameter of the tube and surface tension of the liquid