Analysis of drag reduction and heat transfer under a non-similar condition between turbulent flow and temperature fields

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Numerical simulations of the velocity and temperature fields in a fully developed turbulent channel flow were carried out. It is well known that the similarity between the heat transfer and the friction exists in such a turbulent wall bounded flow as the Reynolds analogy. We applied a turbulence control to reduce the drag by blowing and suction on the channel walls. And it is found that the heat transfer rate reduces as well as the skin friction does. But the rate of the heat transfer to the momentum transfer is a littie larger than that of the natural (no-control) flow. The correlation between velocity and temperature fluctuations weakens owing to the local pressure gradient when the blowing velocity is imposed on the wall against the fluid moving towards the wall.