Home
Back
Formula Used:
| From: | To: |
The formula calculates the top width of a channel section based on Froude number, wetted surface area, and discharge for gradually varied flow. It's derived from fundamental hydraulic principles and provides important geometric information about open channel flow sections.
The calculator uses the formula:
Where:
Explanation: The formula relates the top width of a channel to flow characteristics including Froude number (dimensionless parameter describing flow regime), wetted surface area, gravitational acceleration, and discharge rate.
Details: Calculating top width is essential for hydraulic engineering design, flood prediction, channel capacity analysis, and understanding flow behavior in open channels. It helps determine the cross-sectional geometry needed for efficient water conveyance.
Tips: Enter Froude number (dimensionless), wetted surface area in square meters, and discharge in cubic meters per second. All values must be positive numbers greater than zero.
Q1: What is the Froude number and why is it important?
A: The Froude number is a dimensionless parameter that characterizes flow regime in open channels. It distinguishes between subcritical (Fr < 1), critical (Fr = 1), and supercritical (Fr > 1) flow conditions.
Q2: How is wetted surface area different from wetted perimeter?
A: Wetted surface area refers to the total area in contact with water, while wetted perimeter is the length of the channel boundary in contact with water. Both are important hydraulic parameters but serve different purposes in calculations.
Q3: What are typical values for Froude number in natural channels?
A: In natural streams and rivers, Froude numbers typically range from 0.1 to 0.8 for subcritical flow. Values approaching or exceeding 1 indicate critical or supercritical flow conditions.
Q4: When is this formula most applicable?
A: This formula is particularly useful for gradually varied flow conditions in prismatic channels where the relationship between top width and other hydraulic parameters needs to be established for design or analysis purposes.
Q5: Are there limitations to this equation?
A: The formula assumes steady, uniform flow conditions and may have limitations in highly irregular channels, rapidly varied flow conditions, or where significant sediment transport occurs.