Optimal control of dissimilar heat and momentum transfer in a fully developed turbulent channel flow
Optimal control of dissimilar heat and momentum transfer in a fully developed turbulent channel flow
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充分发展的湍流通道流中异种热和动量传递的优化控制
DOI：
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发表时间：
2013
影响因子：
3.7
通讯作者：
N. Kasagi
中科院分区：
文献类型：
--
作者：
A. Yamamoto;Y. Hasegawa;N. Kasagi
抽象持续的摩擦减少和热传递增加在完全开发的通道流中实现，平均传输方程和动量和热的壁边界条件具有相同的形式。控制输入及其时空分布是根据最佳控制理论确定的。速度，摩擦阻力从不受控制的值降低了24％，而热传递的优化速度则增加了一倍以上。波长在壁单元中约为250，相位速度约为块状平均速度的30％。场表明，行驶波输入通过两个不同的机制有助于增强热传递，即直接修改相干速度和热场，以及对随机场的间接影响。保守的标量本质上是不同的，这是实现湍流剪切流中相似传热增强的关键。
Abstract Sustained friction drag reduction and heat transfer augmentation are simultaneously achieved in a fully developed channel flow where the averaged transport equations and wall boundary conditions for momentum and heat have identical form. Zero-net-mass-flux wall blowing and suction is assumed as a control input and its spatio-temporal distribution is determined based on optimal control theory. When the root-mean-square value of the control input is 5 % of the bulk mean velocity, the friction drag is decreased by 24 % from the uncontrolled value, whereas the heat transfer is more than doubled. Optimizations with different amplitudes of the control input and different Reynolds numbers reveal that the optimal control inputs commonly exhibit the property of a downstream travelling wave, whose wavelength is ∼250 in wall units and phase velocity is ∼30 % of the bulk mean velocity. Detailed analyses of the controlled velocity and thermal fields show that the travelling wave input contributes to dissimilar heat transfer enhancement through two distinct mechanisms, i.e. direct modification of the coherent velocity and thermal fields and an indirect effect on the random fields. The present results show that the divergence-free velocity vector and the conservative scalar are essentially different, and this is a key to achieving dissimilar heat transfer enhancement in turbulent shear flows.
金钱与时间：从能耗和便利性角度评估流量控制
影响因子：
3.7
作者：
Frohnapfel;Hasegawa;Quadrio
通讯作者：
Quadrio