Conservation equations of chemical species

The chemical species i flowing in through AA per unit time at Xj is given by puY AA 

The rate of mass loss of the chemical species i due to the chemical reaction in the space AAAx is given by 

The chemical species i conserved in AAAx is given by puYiAA + -pDidYi/dx)AA - cojAAAx 

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The additional introduction of turbulent viscosity to the stress tensor in Eq. (17.60) is called the Reynold s stress tensor, while in the energy equation the fluctuating component increases the thermal diffusivity by a turbulent contribution ( turb)- The same correction appears in the conservation equations of chemical species, where the presence of a diflusion associated to fluctuations is introduced. 

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