Fluid Flow
Lecture No. 5
CLASSIFICATION OF FLUID FLOW AND THE CONTINUITY EQUATION
5.1 Classification of Fluid Flow
Uniform flow
If the velocity of the fluid is the same in magnitude and direction at every point in the fluid the flow is said to be uniform.
Non-uniform flow A non-uniform flow is one where the velocities at different points at a given instant are not the same. Every fluid that flows near a solid boundary will be non-uniform because the fluid at the boundary takes the velocity of the boundary which is usually zero.
Steady flow A steady flow is one in which the conditions (i.e., velocity, pressure, cross-section) may vary from point to point but do not change with time.
Unsteady flow If at any point in the fluid, the conditions change with time, the flow is unsteady. In reality, there are always slight variations in velocity and pressure; however, if the average values are constant, the flow may be considered steady.
Steady uniform flow In steady uniform flow, conditions do not change with position in the stream or with time. Example: Flow of water in a pipe of constant diameter at constant velocity
Steady non-uniform flow In this flow classification, conditions change from point to point in the stream but do not change with time. Example: Fluid flow in a tapering pipe with constant velocity at the inlet. Velocity will change as the fluid moves along the length of the pipe toward the exit.
Unsteady uniform flow In this flow, the conditions at all points are uniform at any given instant but change with time. Example: Flow of fluid through a constant-diameter pipe connected to a pump pumping at constant rate which is then switched off.
Unsteady non-uniform flow If every condition of the flow changes from point to point and changes with time at every point, the flow is unsteady and non-uniform. Example: Waves in a channel
Classification based on restraining effect of solid boundary
Closed-conduit flow
Flows which are
CLASSIFICATION OF FLUID FLOW AND THE CONTINUITY EQUATION
5.1 Classification of Fluid Flow
Uniform flow
If the velocity of the fluid is the same in magnitude and direction at every point in the fluid the flow is said to be uniform.
Non-uniform flow A non-uniform flow is one where the velocities at different points at a given instant are not the same. Every fluid that flows near a solid boundary will be non-uniform because the fluid at the boundary takes the velocity of the boundary which is usually zero.
Steady flow A steady flow is one in which the conditions (i.e., velocity, pressure, cross-section) may vary from point to point but do not change with time.
Unsteady flow If at any point in the fluid, the conditions change with time, the flow is unsteady. In reality, there are always slight variations in velocity and pressure; however, if the average values are constant, the flow may be considered steady.
Steady uniform flow In steady uniform flow, conditions do not change with position in the stream or with time. Example: Flow of water in a pipe of constant diameter at constant velocity
Steady non-uniform flow In this flow classification, conditions change from point to point in the stream but do not change with time. Example: Fluid flow in a tapering pipe with constant velocity at the inlet. Velocity will change as the fluid moves along the length of the pipe toward the exit.
Unsteady uniform flow In this flow, the conditions at all points are uniform at any given instant but change with time. Example: Flow of fluid through a constant-diameter pipe connected to a pump pumping at constant rate which is then switched off.
Unsteady non-uniform flow If every condition of the flow changes from point to point and changes with time at every point, the flow is unsteady and non-uniform. Example: Waves in a channel
Classification based on restraining effect of solid boundary
Closed-conduit flow
Flows which are