\(\frac{\alpha_{q}^{n+1}\rho_{q}^{n+1}-\alpha_{q}^{n}\rho_{q}^{n}}{\text{Δt}}V+\sum_{f}\left(\rho_{q}U_{f}^{n}\alpha_{q,f}^{n}\right)=\left[\sum_{p=1}^{n}{\left({\dot{m}}_{\text{pq}}-{\dot{m}}_{\text{qp}}\right)+S_{\alpha_{q}}}\right]V\) (1)