Dissimilar heat transfer enhancement in a fully developed laminar channel flow subjected to a traveling wave-like wall blowing and suction

Abstract

A series of numerical simulations of heat and momentum transfer in a fully developed incompressible laminar channel flow subjected to a traveling wave-like wall blowing and suction is conducted. By systematically changing the wavelength and the phase speed of a traveling wave, their impacts on the Stanton number, the friction coefficient and their ratio, i.e., the analogy factor, are evaluated at different Reynolds numbers. Significant dissimilar heat transfer enhancement is confirmed when a downstream traveling wave is applied. It is also found that such a control input remains advantageous even when the power consumption for applying the control input is taken into consideration. In order to analyze the dissimilar responses of the velocity and thermal fields to the applied control input, we introduce the influential layer thickness and the magnitude of the Reynolds shear stress and the convective heat flux. It is shown that the influential layer thicknesses for the velocity and thermal fields are kept relatively similar, and can be well correlated with the Stokes layer thickness determined by the temporal period of the wave and the fluid viscosity for fast traveling waves. In contrast, significant difference in their magnitudes is confirmed. Phase and budget analyses of the coherent velocity and thermal fluctuations reveal that the continuity constrain on the velocity field is the primary reason for dissimilar heat transfer enhancement.