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

对充分发展的槽道湍流的速度场和温度场进行了数值模拟。众所周知，在雷诺类比这样的湍流壁面边界流中，传热和摩擦之间存在相似之处。我们应用了湍流控制，通过在通道壁上吹气和吸气来减少阻力。计算结果表明，换热系数和壁面摩阻都有不同程度的降低。但热传递与动量传递的比率略大于自然(无控制)流动的比率。当吹气速度施加在壁面上时，由于局部压力梯度的作用，速度和温度波动之间的相关性减弱。

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.