Introduction to Food Engineering

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Volumetric Flow Rate and Friction in Fluid Flow

Learning Outcomes

At the end of this module, you will be able to:

  1. calculate volumetric flow rate in a pipe
  2. describe forces due to friction in a fluid flow
  3. predict friction factor for given flow conditions

In the last module, we developed an expression for the velocity profile for a fluid flowing in a pipe. In this module, we will extend that discussion to determine the volumetric flow rate. In the following video, we will derive an expression for this purpose, commonly called Poiseuille’s Law. We will also develop equations for mean and maximum velocity in a pipe for laminar and turbulent flow.

In the next video, we will consider forces due to friction between the flowing fluid and the internal pipe surface. We will develop an expression for a factor to represent friction, called friction factor. We will obtain its value for a given flow condition using Moody’s diagram

In a future module, we will observe that the friction factor is vital in calculating the pumping requirements of a fluid. You obtained the value of friction factor from Moody’s diagram or by using a mathematical equation, as shown in the last video. In the next video, we will use a spreadsheet to calculate the friction factor.


In this module, you learned how to determine the volumetric flow rate of a fluid flowing in a pipe. The mathematical expression for the volumetric flow rate is called Poiseuille’s equation. The friction factor is necessary for designing pumping systems. You learned how to obtain the value of friction factor using Moody’s diagram. In a solved example, you used a spreadsheet, programmed with an empirical equation, to get friction factor.