Hydraulic Diameter Calculator

The Formula

The formula for calculating hydraulic diameter is:

Where:

• D_h: Hydraulic diameter (m)
• A: Cross-sectional area of the duct or channel (m²)
• P: Wetted perimeter of the duct or channel (m)

Importance of Hydraulic Diameter

The hydraulic diameter is a crucial parameter in fluid mechanics and heat transfer calculations, especially for non-circular ducts and channels. It allows engineers to:

• Apply circular pipe flow equations to non-circular geometries
• Calculate Reynolds number for determining flow regime (laminar or turbulent)
• Estimate friction factors and pressure drops in fluid systems
• Analyze heat transfer in various duct shapes

Example Calculation

Let's calculate the hydraulic diameter for a rectangular duct with width 0.3 m and height 0.2 m:

1. Cross-sectional area: A = 0.3 × 0.2 = 0.06 m²
2. Wetted perimeter: P = 2 × (0.3 + 0.2) = 1.0 m
3. Hydraulic diameter: D_h = (4 × 0.06) / 1.0 = 0.24 m