The second-order moment combustion model,proposed by the authors is validated using the direct numerical simulation(DNs) of incompressible turbulent reacting channel flows.The instantaneous DNS resultsshow the near-wall strip structures of concentration and temperature fluctuations.The DNS statistical results give the budget of the terms in the correlation equations,showing that the production and dissipation terms are most important.The DNS statistica]data are used to validate the closure modeIin RANS second-order moment(SOM) combustion model.It iS found that the simulated diflusion and production terms are in agreement with the DNS data in most flow regions,except in the near-wall region,where the near-wall modification should be made,and the closure model for the dissipation term needs further improvement.The algebraic second-order moment(ASOM) combustion model iS well validated by DNS.