#### Hydraulic diameter equation

## What is meant by hydraulic diameter?

Hydraulic diameter (Dh) is defined as_Dh=4A/pwhere A is the cross-sectional area and p is the wetted perimeter of the cross section. From: Thermal-Hydraulics of Water Cooled Nuclear Reactors, 2017.

## What is hydraulic diameter used for?

Hydraulic diameter is mainly used for calculations involving turbulent flow. Secondary flows can be observed in non-circular ducts as a result of turbulent shear stress in the turbulent flow. Hydraulic diameter is also used in calculation of heat transfer in internal-flow problems.

## How do you find the hydraulic diameter of a rectangular duct?

dh = 4 A / p (1) where dh = hydraulic diameter (m, ft) A = area section of the duct or pipe (m2, ft2) p = “wetted” perimeter of the duct or pipe (m, ft) Note! – inches are commonly used in the Imperial unit system.

## What is hydraulic radius?

: the ratio of the cross-sectional area of a channel or pipe in which a fluid is flowing to the wetted perimeter of the conduit.

## What is Hydraulic depth?

For use in Froude number and energy relationships in open channel flow hydraulics, mean depth, h_{m}, is defined as the depth which, when multiplied by the top water surface width, T, is equal to the irregular section area, A, shown on figures 2-4a and 2-4b, of the flow section and is commonly used for critical flow

## What is equivalent pipe diameter?

The equivalent diameter is the diameter of a circular duct or pipe that for equal flow gives the same pressure loss or resistance as an equivalent rectangular duct or pipe.

## How do you find the hydraulic radius?

From the hydraulic radius definition: RH = A/P, where A is the cross sectional area of flow and P is its wetted perimeter. From the diagram it is clear that A = by and P = 2y + b, so the hydraulic radius is: RH = by/(2y + b) for an open channel flow through a rectangular cross section.

## How is Reynolds number calculated?

Reynolds NumberRe = ρ u L / μ = ρ u^{2} / (μ u / L) = u L / ν (1) where. Re = Reynolds Number (non-dimensional) ρ = density (kg/m^{3}, lb_{m}/ft^{3}) Re = ρ u d_{h} / μ = u d_{h} / ν (2) where. d_{h} = hydraulic diameter (m, ft)Re = 7745.8 u d_{h} / ν (2a) where. Re = Reynolds Number (non dimensional) u = velocity (ft/s) d_{h} = hydraulic diameter (in)

## How is hydraulic diameter defined in non circular tubes?

The hydraulic diameter, D_{h}, is a commonly used term when handling flow in non-circular tubes and channels. Using this term, one can calculate many things in the same way as for a round tube. In this equation A is the cross-sectional area, and P is the wetted perimeter of the cross-section.

## How do you find the diameter of a duct?

Wrap a string or other flexible object completely around the circumference of the ductwork. Mark the string or object where the ends meet.Unwrap the string and stretch it out on a flat surface. Divide the above measurement by pi (3.14) to calculate the diameter of your ductwork.

## How do you find the wetted perimeter of a pipe?

The area of flow is calculated as the total cross-sectional area of the pipe minus the cross-sectional area of the empty space above the water. Similarly, the wetted perimeter is calculated as the total perimeter minus the dry perimeter at the top of the pipe.

## What is most economical channel section?

A channel section is considered as the most economical or most efficient when it passes a maximum discharge for given cross section area, resistance coefficient, and bottom slope.

## What is critical depth?

In biological oceanography, ‘Critical Depth’ is defined as a hypothesized surface mixing depth at which phytoplankton growth is precisely matched by losses of phytoplankton biomass within this depth interval. This concept is useful for understanding the initiation of phytoplankton blooms.