Which of the following is not a characteristic of uniform flow?

• A. Same depth at every section
• B. Flow rate is constant
• C. Friction loss is variable
• D. Friction slope equals channel bottom slope

Answer: (C)

Uniform flow is defined as a flow condition where the velocity and other flow characteristics remain constant along a length of the channel or conduit. Understanding the characteristics of uniform flow helps in designing hydraulic systems and predicting water behavior in open channels.

One characteristic of uniform flow is that the flow rate is constant along the flow path. This means that the volume of water flowing through any section of the channel remains the same over time. Additionally, in uniform flow, the depth of the flow is the same at every cross-section of the channel, indicating a consistent hydraulic state.

Another essential aspect of uniform flow is that the friction slope (the slope of the energy loss due to friction) is equal to the channel bottom slope. This signifies that the energy losses are balanced by the gravitational forces acting on the fluid, maintaining a steady-state flow condition.

The characteristic regarding friction loss being variable does not align with the definition of uniform flow. In a uniform flow scenario, the friction loss is consistent throughout the channel, directly related to the constant velocity and depth. Therefore, the fluid experiences a uniform resistance that does not change, which contradicts the concept of variable friction loss.

This understanding of uniform flow characteristics is crucial for anyone preparing for the PE Civil Transportation exam, as it forms the