其他摘要：The direct numerical simulation of a fully developed turbulent flow with heat transfer and the direct numerical simulation of a perturbed turbulent channel flow with heat transfer, has been performed. Buoyancy effects were neglected, thus the temperature was considered as a passive scalar. For the first calculation, for non-perturbed flow, the isoflux, constant temperature, and uniform energy source boundary conditions has been used for the thermal field. Mean and turbulence values of velocity and temperature fields are compared with data from the literature for the isoflux case. The second calculation for the perturbed channel flow simulation with heat transfer, has been performed to investigate velocity and temperature fields dissimilarity. For this second calculation the uniform energy source case for the thermal field was used. Perturbations were applied into the flow locally by blowing from a span-wise slot at the lower wall, and suction from a similar slot at the upper wall. In this first work on perturbed turbulent channel flow, no developing calculation was used, rather than very small values of the transpiration velocity and slot width has been used in conjunction with a long periodic computational domain. The main results from this study show that the skin-friction and the Stanton number suffer clear changes owing to local blowing or suction. While local blowing yields a decreases of the skin-friction and the Stanton number, local suction increases these coefficients. Qualitatively the effects on both coefficients are similar for every perturbation. The local extremes, however, for the skin-friction are smaller than those for St. And also the region of velocity field affected by the perturbation is larger than for the temperature field. The budgets for the axial mean velocity and for the mean temperature show that the main source of dissimilarity for blowing is the mean pressure gradient and the convection terms. Mean pressure gradient make mean velocity to change in the wall region in a slight smoother way than mean temperature. This small differences in the variation of mean velocity and temperature yields dissimilarities in the turbulence production in the budget of the second moment of the fluctuations of axial velocity and temperature. The perturbed mean flow transfers energy to turbulence spreading out its effect into a larger region than those affected in the thermal field. The responsible for these differences in the mean flow and mean thermal field is the non-local effect of the mean pressure gradient on convection terms of the mean momentum equation. For the fluctuations of axial velocity and temperature fields the main causes of dissimilarity are the small differences in the behavior of the gradient of the mean values, which yields dissimilarity mainly in the turbulence production term.
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