Fluid Mechanics - Kinematics of Flow and Ideal Flow

Kinematics is defined as that branch of science which deals with the motion of particles without considering the forces causing the motion. The velocity at any point in a flow field at any time is studied in this branch of fluid mechanics.

Types of Fluid Flow :-

1) Steady and Unsteady Flows :- Steady flow is defined as that type of flow in which the fluid characteristics like velocity , pressure , density etc. at a point do not change with time.
Unsteady Flow is that type of flow , in which the fluid characteristics like velocity , pressure , density etc. at a point change with respect to time.

2) Uniform and Non-Uniform Flow :- Uniform flow is defined as that type of flow in which the velocity at any given time does not Change with respect to time.
Non-uniform Flow is defined as that types of flow in which the velocity at any given time changes with respect to time.

3) Laminar And Turbulent Flow :- Laminar flow is defined as that types of flow in which the fluid particles move along a well-defined path or stream line and all the stream lines are straight and parallel.
Turbulent Flow is defined as that types of flow in which the fluid particles move in a zig-zag way. Due to the movement of fluid particles in a zig-zag way, the Eddies formation takes place which are responsible for high energy loss.

4) Compressible and Incompressible Flows :- Compressible flow is defined as that types of flow in which the density of a fluid changes from point to point or in other words the density is not constant for the fluid.
Incompressible flow is defined as that types of flow in which the density is constant for the fluid flow. Liquids are generally incompressible while gases are compressible.

5) Rotational and Irrotational Flows :- Rotational flow is defined as the that types of flow in which the fluid particles while flowing along a stream lines , also rotate about their own axis.
Irrotational flow is defined as that types of flow in which the fluid particles while flowing along a stream lines , but do not rotate about their own axis.

One-, Two-, and Three - Dimensional Flows :- One - dimensional is that types of flow in which the flow parameters such as velocity is a function of time and one space co-ordinate only , say x.
Two-dimensional flow is that types of flow in which the velocity is a function of time and two rectangular space co-ordinates say x and y.
Three-dimensional flow is that types of flow in which the velocity is a function of time and three mutually perpendicular directions.

- Rate of Flow and Discharge :- It is defined as the quantity of fluid flowing per second through a section of a pipe or a channel.

- Continuity Equation :- The equation based on the principle of conservation of mass is called continuity equation.  Thus for a fluid flowing through the pipe at all the cross-section , the quantity of fluid per second is constant.