A model was proposed to evaluate correlation of turbulent fluctuations of reactors' concentrations. It enables adequate prediction of the pollutant dispersion with bimolecular chemical reaction using RANS type turbulence model. It is composed of turbulent kinetic energy (TKE), dissipation rate of TKE, spatial gradients of mean concentrations, and a model coefficient. The model was validated against LES of dispersion and bimolecular chemical reaction in a turbulent channel flow. It was confirmed that the model could predict accurately the correlation except near-wall region. Although the model coefficient had a Reynolds number dependency, it reached a finite value (nearly 0.05) in high Reynolds number region. A test calculation with a RANS type turbulence model employing the proposed correlation model was also conducted. It was found that it could make improvements in the prediction of the reaction rate.
