If the velocity of flow at a particular point or at a section does NOT change with respect to time, then the flow is known as:

Explanation:
Steady flow: A flow is considered to be steady when conditions at any point in the fluid do not change with time i.e.

\(\frac{{\partial V}}{{\partial t}} = 0\)

But it may vary from one point to another and also the properties do not change with time, i.e.

\(\frac{{\partial p}}{{\partial t}} = 0,\frac{{\partial ρ }}{{\partial t}} = 0,\frac{{\partial T}}{{\partial t}} = 0\)

Unsteady flow: A flow is said to be unsteady when the flow parameters at any point change with time.

For unsteady flow, \(\frac{{\partial V}}{{\partial t}} \ne 0,\frac{{\partial ρ }}{{\partial t}} \ne 0,\frac{{\partial T}}{{\partial t}} \ne 0\)

Laminar flow:

Laminar Flow: Laminar flow is the flow in which fluid particles flow in layers. Each layer moves smoothly past the adjacent layer with little or no intermixing. There is no intermingling of fluid particles across the cross-section. So laminar flow resembles streamline flow.

Turbulent flow – Turbulent flow occurs at relatively larger velocities and is characterized by chaotic behaviour, irregular motion, large mixing and eddies. For such flows, inertial effects are more pronounced than the viscous effects.

• Mathematically the velocity field of turbulent flow is represented as\(V = \bar V + V'\) or the velocity fluctuates at small time scales around a large time-averaged velocity.
• Similarly,  \(P = \bar P + P',T = \bar T + T'\)etc.
• Parameter Reynolds number \(\left( {\frac{{\rho vd}}{\mu }} \right)\) is used to characterize Laminar and Turbulent flow.
• If Re < 2100 for pipe flow the flow is laminar and if Re > 104 the flow is turbulent.