\rho \overline{u}_{i}\frac{\partial \overline{u}_{j}}{\partial x_{j}}=\rho \overline{f}_{i}+\frac{\partial }{\partial x_{j}}[-\overline{p}\delta _{ij}+2\mu\overline{\\S}_{ij}-\rho\overline{u_{i}^{'}u_{j}^{'}} ] {{math|α}}