# Reynolds decomposition #turbulence #in-progress Reynolds decomposition refers to the process of separating a field into a average quantity and a fluctuating part. If we have a time-dependent quantity $U$, then this decomposition can be expressed as $U = \overline{U} + U'$ where $\overline{U}$ denotes the mean of $U$, and $U'$ denotes the fluctuations in $U$. ^28d0d7