论文标题
湍流动量与热传输之间的异小差分析平面couette湍流
Spectral analysis on dissimilarity between turbulent momentum and heat transfers in plane Couette turbulence
论文作者
论文摘要
湍流中不同尺度之间的非线性相互作用会导致湍流能量的间尺度和空间传输，以及从工程学的角度来看，这种比例相互作用在湍流传热机制中的作用也至关重要。在本研究中，我们调查了一个湍流平面库特流动，并在prandtl数字为0.71的被动量表热传递，以解决速度和温度场中的比例相互作用之间的相似性/差异。使用恒定差异边界条件，以使平均速度和温度曲线相似，然后比较湍流能量的光谱传输预算以及与温度相关的统计量的光谱传输预算。我们表明，与动量转移相比，湍流传热是在相对较小的流长度尺度上发生的，尽管由于PRANDTL数量小于1。分子扩散在温度场中更为重要。对温度相关光谱的传输预算的详细分析表明，与速度场相比，温度场中的尺度相互作用在温度场中的量表相互作用提供了更多的能量。如此明显的温度级联反应会导致小尺度上的更耗能的温度波动，最终导致湍流热和动量转移光谱之间的相似性。
Nonlinear interaction between different scales in turbulence results in both interscale and spatial transport of turbulent energy, and the role of such scale interactions in turbulent heat transfer mechanism is also of practical importance from the engineering viewpoint. In the present study, we investigate a turbulent plane Couette flow with passive-scalar heat transfer at the Prandtl number 0.71, in order to address the similarity/difference between the scale interactions in the velocity and temperature fields. The constant-temperature-difference boundary condition is used so that the mean velocity and temperature profiles are similar, and then the roles of interscale and spatial transports are compared for the spectral transport budgets of the turbulent energies and temperature-related statistics. We show that turbulent heat transfer occurs at relatively small streamwise length scales compared to momentum transfer, although molecular diffusion is more significant in the temperature field as the Prandtl number is less than 1. Detailed analysis on the transport budgets of the temperature-related spectra shows that scale interactions in temperature field supply more energy to small scales than those in velocity field. Such significant temperature cascade leads to more energetic temperature fluctuation at small scales, which eventually results in the dissimilarity between the spectra of turbulent heat and momentum transfers.
