Steady fluid flow:
The flow of fluid is said to be steady if certain physical variables of the fluid such as pressure, density and speed at every point of the fluid do not change with time.
Example: A slow flow of water in a clam river.
Non-steady fluid flow:
The flow of fluid is said to be non-steady if the physical variables of the fluid such as pressure, density and speed changes with time from one point to another.
Example: A waterfall. The flow of water from the waterfall is non-steady.
Irrotational fluid flow:
The flow of fluid is said to be irrotational flow if the particle which move with the stream are not rotate about the axis which pass through its center of mass.
Example: The vortex formed when water drains from a bathtub.
Rotational fluid flow:
The flow of fluid is said to be rotational flow if the particle which move with the stream are rotate about an axis which pass through its center of mass.
Example: The vortex formed in the flowing water.
Compressible fluid flow:
The flow of fluid is said to be compressible flow if the density of the fluid changes at any point. In such flow, the density of the fluid flow is the function of x, y, z coordinates and time t.
Example: Gas in the vessel through a moveable piston.
Incompressible fluid flow:
The flow of fluid is said to be incompressible flow if the density of the fluid does not change at any point.
Example: The volume of the liquid that are placed in a vessel cannot be compressed.
Viscous fluid flow:
The flow of fluid is said to be viscous fluid flow if large external forces or pressure are required to maintain the flow of the flow. Such viscous flow depends on the temperature of the fluid.
Example: The flow of most lubricant oil is viscous flow.
Non-viscous fluid flow:
The flow of fluid is said to be non-viscous fluid flow if negligible internal friction arise in the fluid flow. Such flow required small external forces or pressure are required to maintain the flow of the flow.
Example: The flow of water in a calm river is non-viscous fluid flow.