Directed co-flow effects on local entropy generation in turbulent heated round jets

•The directed co-flow effects on local entropy generation rate have studied.•The first order closure model in turbulent and heated round jets was used.•The directed co-flow with a positive angle enhances the mixing.•The local entropy generation rate increases with a positive angle. In the present paper, we have studied numerically the directed co-flow effects on local entropy generation rate in turbulent and heated round jets. The first order closure model was used and compared to existing experimental findings. The numerical results of the mean and turbulent quantities of the entropy generation rate and of the Merit number have been presented and discussed. The results obtained show that the directed co-flow with a positive angle enhances the mixing. Consequently, the local entropy generation rate increases progressively with the deviation angle.