What Is the Open Channel Critical Depth & Specific Energy Calculator?
Critical depth yc is the depth at which a given discharge passes with the absolute minimum specific energy.
At critical depth, surface gravity wave celerity equals flow velocity, preventing upstream wave propagation.
How Does the Open Channel Critical Depth & Specific Energy Calculator Work?
Comparing actual bed slope S0 to critical slope Sc classifies channels as Mild (S0 < Sc), Critical (S0 = Sc), or Steep (S0 > Sc).
Mild slopes support subcritical normal flow, while steep slopes support supercritical normal flow.
Open Channel Critical Depth & Specific Energy Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
Rectangular channel critical depth, minimum energy, and critical slope formulations.
How to Use the Open Channel Critical Depth & Specific Energy Calculator
- Input channel width, flow rate, Manning roughness, and bed slope.
- Check critical depth, minimum specific energy, critical slope, and slope regime.
Step-by-Step Example Calculation
Rectangular Concrete Canal
Input Values:
Understanding Your Result
If normal depth yn > yc, flow is subcritical; if yn < yc, flow is supercritical.
Factors That Affect the Result
- Critical depth depends solely on discharge and channel geometry, completely independent of roughness or slope.
When Should You Use This Calculator?
- Canal design, culvert inlet/outlet control sizing, and open-channel flume calibrations.
Assumptions & Limitations
- Assumes a prismatic rectangular channel with hydrostatic pressure distribution.
Frequently Asked Questions
Calculation Accuracy & Reference Note
Standard open channel flow energy principle.