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Hydraulic Jump Sequent Depth & Energy Dissipation Calculator

A hydraulic jump is a rapid open-channel transition from supercritical shooting flow (Froude Fr > 1) to subcritical tranquil flow (Fr < 1).

Depth entering the jump from spillway or sluice gate.

High-speed flow velocity entering the jump.

Calculated Result
3.04 m

Sequent Depth (y2)

Energy Head Loss

1.99 m

Energy Dissipated

38.2%

Stilling Basin Length

18.5 m

Calculation Breakdown

  1. Bélanger Sequent Depth (y2)(y1 / 2) · [√(1 + 8·Fr1²) - 1] = 3.037 m
  2. Dissipated Energy Head Loss (Delta_E)(y2 - y1)³ / (4·y1·y2) = 1.985 m
  3. Stilling Basin Length (USBR)L ≈ 6.1 · y2 = 18.52 m

What Is the Hydraulic Jump Sequent Depth & Energy Dissipation Calculator?

A hydraulic jump occurs when high-velocity supercritical water abruptly decelerates, creating intense turbulent rollers that dissipate kinetic energy.

How Does the Hydraulic Jump Sequent Depth & Energy Dissipation Calculator Work?

Equates specific force (momentum plus hydrostatic thrust) across the jump to solve for downstream subcritical sequent depth y2.

Hydraulic Jump Sequent Depth & Energy Dissipation Calculator Formula & Variables

The core mathematical equation utilized by this calculator is expressed as:

y_2 = rac{y_1}{2} left( sqrt{1 + 8 ext{Fr}_1^2} - 1 ight), quad Delta E = rac{(y_2 - y_1)^3}{4 y_1 y_2}, quad L approx 6.1 y_2

Bélanger momentum equation for hydraulic jump sequent depth and head loss.

How to Use the Hydraulic Jump Sequent Depth & Energy Dissipation Calculator

  1. Input upstream supercritical depth y1 in meters and initial velocity V1 in m/s.

Step-by-Step Example Calculation

Spillway Apron Stilling Basin

Input Values:

upstreamDepthY1M:0.6
supercriticalVelocityV1MS:9.5
Worked Steps: Initial Froude Fr1 = 3.92, Sequent depth y2 = 3.03 m, Energy head loss = 2.01 m (38.6% dissipated), Basin length = 18.5 m.

Understanding Your Result

Displays required downstream sequent depth y2, dissipated energy head in meters, dissipation efficiency %, and recommended stilling basin length.

Factors That Affect the Result

  • Optimum energy dissipation occurs when initial Froude number Fr1 is between 4.5 and 9.0 (steady, well-balanced jump).

When Should You Use This Calculator?

  • Designing dam spillway aprons, USBR Type II/III stilling basins, drop structures, and open-channel flumes.

Assumptions & Limitations

  • Applies to rectangular horizontal channels with negligible bed friction across the jump reach.

Frequently Asked Questions

Calculation Accuracy & Reference Note

Standard Bélanger momentum open-channel hydraulics formulation.

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