DNS and Modelling of Turbulent Heat Transfer for Low to Medium-High Prandtl Number Fluids

随着超级计算机和并行计算机的发展，湍流的直接数值模拟越来越多地应用于各种构型和边界条件。DNS为我们提供了湍流量的详细分布，如平均速度、温度、湍流热通量和输运方程的预算。另一方面，湍流的建模仍然是湍流热和流体流动工程分析的重要工具，因为DNS的应用现在仅限于具有相对简单几何形状的低雷诺数湍流。从DNS中获得的信息对湍流模型的改进有重要的贡献。在本研究中，对具有标量输运的完全发育的通道流动进行了DNS，其中在几种热条件下研究了各种普朗特数流体。建立了一个标量传输模型，并与获得的DNS结果进行了比较。

With an aid of recent development in the super and parallel computers, the deirect numerical simulation (DNS) of turbulence is now performed increasingly for various configulations and boudary conditions. The DNS provides us with the detailed distributions of the turbulent quantities, such as the averaged velocity, temperature, turbulent heat flux and the budgets of transport equations. The modelling of the turbulence, on the other hand, is still an important tool in the engineering analysis of the turbulent heat and fluid flow, because the application of the DNS is now limited only to low Reynolds number turbulence with relatively simple geometries. The information obtained from the DNS contributessignificantly to the refinement of the turbulence modelling.In the present study, DNS of the fully developed channel flow with the scalar transport were performed, where various Prandtl number fluids were examined with several kinds of thermal conditions imposed. A scalar transport model was developed and examined in comparison with the obtained DNS results.