ASCE Hydraulics and Fluid Mechanics 2

Question 1

Manning's roughness coefficient (n) in open channel flow primarily accounts for:

Accepted Answer

Boundary resistance due to channel surface texture

Answer

Manning's n is an empirical coefficient that quantifies energy losses due to boundary friction from the channel's surface roughness (concrete, earth, rock, vegetation, etc.).

Question 2

The hydraulic radius (R) used in Manning's equation is defined as:

Accepted Answer

The ratio of flow area to wetted perimeter

Answer

Hydraulic radius R = A/P, where A is the cross-sectional flow area and P is the wetted perimeter, representing the efficiency of the channel shape in conveying flow.

Question 3

Water hammer in a pipeline is primarily caused by:

Accepted Answer

Rapid changes in flow velocity such as sudden valve closure

Answer

Water hammer occurs when flow velocity changes rapidly (e.g., sudden valve closure), converting kinetic energy into pressure surges that propagate as pressure waves through the pipe at acoustic velocity.

Question 4

Which of the following best describes specific energy in open channel flow?

Accepted Answer

Energy per unit weight measured with respect to the channel bottom as datum

Answer

Specific energy (E = y + V²/2g) is the total energy per unit weight of fluid measured with respect to the channel bottom, combining depth (pressure term) and velocity head.

Question 5

In a pipe network analysis using the Hardy Cross method, what condition must be satisfied at each junction node?

Accepted Answer

Continuity: the algebraic sum of flows at each node must equal zero

Answer

The Hardy Cross method iteratively satisfies both loop equations (sum of head losses = 0) and nodal continuity (sum of inflows = sum of outflows = 0) simultaneously to solve pipe networks.

ASCE - American Society of Civil Engineers Certification Practice Test

ASCE - American Society of Civil Engineers Certification Practice Test

ASCE Hydraulics and Fluid Mechanics 2