Favre averaging is carried out for all dynamical variables except the pressure. For the velocity components, , the Favre averaging is defined as
where the overbar indicates the typical Reynolds averaging, the tilde denotes the Favre averaging and  is the density field. The Favre decomposition of the velocity components is then written as
where  is the fluctuating part in the Favre averaging, which satisfies the condition , that is to say, . The normal Reynolds decomposition is given by , where  is the fluctuating part in the Reynolds averaging, which satisfies the condition . The Favre-averaged variables are more difficult to measure experimentally than the Reynolds-averaged ones, however, the two variables can be related in an exact manner if correlations between density and the fluctuating quantity is known; this is so because, we can write
The advantage of Favre-averaged variables are clearly seen by taking the normal averaging of the term  that appears in the convective term of the Navier-Stokes equations written in its conserved form. This is given by
As we can see, there are five terms in the averaging when expressed in terms of Reynolds-averaged variables, whereas we have only two terms when it is expressed in terms of Favre-averaged variables.