# Entrance Length and Developed Flow

## The entrance length is the length in a tube or duct after an obstruction - until the flow velocity profile is fully developed

Sponsored Links

A fluid flow need some length to fully develop the velocity profile after passing through components like bends, valves, pumps, turbines or similar.

### Entrance Length

The entrance length can be expressed with the dimensionless **Entrance Length Number** as

El = l_{e}/ d(1)

where

El= Entrance Length number

l_{e}= length to fully developed velocity profile (m, ft)

d= tube or duct diameter (m, ft)

### Entrance Length Number for Laminar Flow

The Entrance length number correlates with the Reynolds Number and for laminar flow the relation can be expressed as:

El_{laminar}= 0.06 Re(2)

where

Re= Reynolds Number

### Entrance Length Number for Turbulent Flow

The Entrance length number correlation with the Reynolds Number for turbulent flow can be expressed as:

El_{turbulent}= 4.4 Re^{1/6}(3)

## Related Topics

Sponsored Links

## Related Documents

Sponsored Links