CEN 325: Exam II Review (copy)

Runoff Coefficient

The runoff coefficient will be higher for an asphalt surface than for a forest.

Assumptions of the Rational Formula

1. Short time of concentration (tc). 2. Small watersheds. 3. Rainfall has a constant intensity for a duration equal to the time of concentration.

HGL and EGL Definitions

HGL is coincident with the liquid surface of a piezometer; EGL is coincident with the liquid surface in a stagnation tube.

Froude Number Interpretation

A Froude number less than 1 indicates subcritical flow.

Reynolds Number Interpretation

A Reynolds number greater than 4000 indicates turbulent flow conditions.

Dominant Head Losses in Long Pipes

For hydraulically long pipes, frictional losses dominate.

Pipe Network Flow Relations

In a pipe network, Q3=Q2+Q4 is always true.

Cutoff Head

The cutoff head for the attached pump curve is 59m.

Cavitation Definition

Cavitation occurs when the absolute pressure at the pump inlet decreases below the vapor pressure of the fluid.

Pump Speed and Characteristics Curve

Changing the pump speed will change the pump characteristics curve.

Specific Energy and Flow Depth

Critical flow occurs when specific energy is minimum for a given discharge.

Subcritical and Supercritical Flow Definitions

Subcritical flow is associated with slow and deep, while supercritical flow is associated with fast and shallow.

Specific Energy and Depth Uniqueness

There can be multiple depths for a given specific energy.