Development and validation of a novel structure based method for artificial generation of inlet condition for LES

本课题的目的是开发一种新的基于结构的湍流速度场和标量场的人工合成方法，并对该方法进行验证。本项目是基于申请人之前的工作，在入口用紧凑元件产生湍流速度场，紧凑元件是速度（紊流点法）或涡度（紊流涡法）的载体。考虑到实际的各向异性结构，特别是在壁区，将对该方法进行改进。改进的重点是在考虑结构信息的情况下，合成具有规定统计性质直至二阶矩（自相关、谱、积分长度）的波动场的过程。该方法不仅适用于速度场，而且考虑了标量耗散率的多重分形性质，适用于标量场。进一步的目标是将该方法扩展到可压缩流。验证计算将对流体力学和传热传质的典型流动（通道、边界层、自由剪切流和射流混合器）进行。这项工作的结果将是对考虑各向异性结构的紊流模拟的入口条件生成方法的实质性改进。在项目结束时，生成入口条件的特殊程序程序将提供给所有LES研究小组。

Aim of the research project is the development of a novel structure based method for artificial synthesis of turbulent velocity and scalar fields as well as the validation of this method. The project is based on previous works of the applicant, in which the turbulent velocity field at the inlet is generated with compact element which are carrier of either velocity (Turbulent spot method) or vorticity (Turbulent vortons method). An improvement of the method will be achieved by consideration of realistic anisotropic structures which appears especially in the wall region. The main point of the improvement is the procedure of synthesis of fluctuating fields with prescribed statistical properties up to moments of the second order (autocorrelations, spectra, integral lengths) with consideration of structure informations. The method is applied not only on velocity but also on scalar fields with consideration of multifractal properties of the scalar dissipation rate. The further aim is the extension of the method to compressible flows. The validation calculations will be performed for canonical flows of fluid mechanics and heat and mass transfer (channel, boundary layer, free shear flow and jet mixer). The result of this work will be a substantial improvement of methods for generation of inlet conditions for simulation of turbulent flows with consideration of anisotropic structures. At the end of the project, the special program routine for generation of inlet conditions will be available for all LES research groups.