Average Velocity

average_velocity.jpg

Although the cross sectional velocity distribution inside the ventilating ducts is not constant, the average velocity is used in calculations to determine the appropriate duct size and pressure losses.

By Patrik Tschudin (Flickr) [CC-BY-2.0], via Wikimedia Commons

The average velocity inside a pipe or duct is used in many practical fluid dynamics problems.


The average velocity acting over an area can be computed dividing the volumetric flow rate by the cross sectional area.  Mathematically, this can be written as

 

This is an important relationship since the average velocity is frequently used in fluid problems that are solved using control volumes. 

 

 

 

 

 

 

Learning Objectives:

Definition of average velocity.  How to calculate the average velocity.