ASCE Hydraulics and Fluid Mechanics

Question 1

Which dimensionless number is used to distinguish between laminar and turbulent flow in a pipe?

Accepted Answer

Reynolds number

Answer

The Reynolds number (Re = ρVD/μ) compares inertial to viscous forces and is the standard criterion for laminar vs. turbulent pipe flow, with Re < 2300 generally indicating laminar flow.

Question 2

The Bernoulli equation assumes which of the following conditions?

Accepted Answer

Inviscid, incompressible, steady flow along a streamline

Answer

Bernoulli's equation is derived assuming steady, inviscid (frictionless), and incompressible flow along a single streamline, making it applicable to ideal fluid scenarios.

Question 3

The hydraulic grade line (HGL) represents the sum of which two energy heads?

Accepted Answer

Pressure head and elevation head

Answer

The HGL equals pressure head (p/γ) plus elevation head (z), indicating the height to which water would rise in a piezometer tube at any point in the system.

Question 4

Which formula is most commonly used to calculate head loss due to friction in a full pipe under pressure?

Accepted Answer

Darcy-Weisbach equation

Answer

The Darcy-Weisbach equation (hf = f·L/D·V²/2g) is the most theoretically rigorous and widely accepted formula for calculating frictional head loss in pressurized pipe flow.

Question 5

In open channel flow, critical flow occurs when the Froude number equals:

Accepted Answer

1.0

Answer

Critical flow is defined by a Froude number of exactly 1.0, where the flow velocity equals the wave celerity, representing the boundary between subcritical (Fr < 1) and supercritical (Fr > 1) flow.

ASCE - American Society of Civil Engineers Certification Practice Test

ASCE - American Society of Civil Engineers Certification Practice Test

ASCE Hydraulics and Fluid Mechanics