Volume I - Section V - CFD Methodology 
Page V • 1 
5. CFD METHODOLOGY 
Airflow and heat transfer within a fluid are governed by the principles of conservation of mass, 
momentum, and thermal energy. In order to predict the airflow and temperature, as well as the 
distribution of contaminants at any given point in the animal room space, CFD techniques are 
used to represent the fundamental laws of physics describing fluid flow and heat transfer. 
5.1 Methodology Overview 
This section outlines the fundamental aspects of CFD, the equations utilized, and the 
methodology adopted with respect to the problem at hand. 
5.1.1 What is CFD? 
Computational fluid dynamics can be summarized by the following definitions: 
Computational 
The computational part of CFD means using computers to solve problems in fluid dynamics. 
This can be compared to the other main areas of fluid dynamics, such as theoretical and 
experimental. 
Fluid 
When most people hear the term fluid they think of a liquid such as water. In technical 
fields, fluid actually means anything that is not a solid, so that both air and water are fluids. 
More precisely, any substance that cannot remain at rest under a sliding or shearing stress is 
regarded as a fluid. 
Dynamics 
Dynamics is the study of objects in motion and the forces involved. The field of fluid 
mechanics is similar to fluid dynamics, but usually is considered to be the motion through a 
fluid of constant density. 
CFD is the science of computing the motion of air, water, or any other gas or liquid. 
