Kinetic Theory Method for Large Eddy Simulation of Turbulence

9974289在这项工作中，我们计划探索和应用一种全新的方法来进行湍流的大涡模拟。使用玻尔兹曼动态级表示流。大涡模拟的传统方法是在连续介质水平上求解一组修正的N-S方程。虽然这种方法已经取得了许多有趣的结果，但它也遇到了内在的困难(例如，在边界处提供忠实的湍流行为)。由于最近格子Boltzmann方法的成功，我们相信从一个新的角度来处理这个问题有很大的潜力。也就是说，我们建议使用流体力学的Boltzmann方程表示。这种表示法不仅适用于描述粒子的运动，而且一旦构造了适当的平均过程，也可能成为研究大尺度流体湍流性质的有用方法。在这项工作中，我们计划通过建立这样的玻尔兹曼描述来开展一系列广泛的湍流动力学的理论和计算研究。具体的任务包括模型的建立、模拟结果、记忆和历史效应、壁面模型和边界条件的重新描述以及多相湍流的初始应用。这里要做的工作可能对我们模拟真实世界系统中的流体流动的能力产生长期的影响。湍流中旋涡的大小范围排除了直接求解全尺度系统所有尺度上的流动方程的可能性。格子Boltzmann方法的新颖之处在于，它绕过了传统计算机的一些内在限制，以实现逼真的流动模拟。通过将这种方法与大涡模拟的先进思想相结合，我们希望在这些困难的流动问题上取得不可能的进展。特别是，用于大涡模拟的格子Boltzmann方法允许有效地表达到目前为止逃脱分析的近壁边界条件。这里将要建立的新公式也有可能提出新的计算机体系结构，从而实现全面的流动模拟。

9974289In this work, we plan to explore and apply a fundamentally new approach to large-eddy simulation (LES) of turbulence, viz. the use of a Boltzmann kinetic level representation of the flow. Conventional approaches to LES are based on solving a system of modified Navier-Stokes equations at the continuum level. While such an approach has achieved many interesting results, it also encounters intrinsic difficulties (e.g. in providing faithful turbulent behavior at boundaries). Owing to recent successes with the lattice Boltzmann method, we believe there is significant potential in approaching the problem from a new angle. That is, we propose the use of the Boltzmann equation representation of fluid dynamics. Such a representation is not only suitable for describing particle motions, but may also be a useful way of studying large-scale fluid turbulence properties once some appropriate averaging procedure is constructed. In this work, we plan to carry out an extensive series of theoretical and computational studies of turbulence dynamics by formulating such a Boltzmann description. The specific tasks include model formulation, simulation results, memory and history effects, reformulation of wall models and boundary conditions, and initial applications to multiphase turbulent flows.The work to be done here may have long-lasting impact on our ability to simulate fluid flows in real-world systems. The huge range of eddy sizes in turbulence precludes direct solution of the flow equations at all scales for full-scale systems. The novelty of the lattice Boltzmann method is that it circumvents some of the intrinsic limitations of conventional computers in order to achieve realistic flow simulations. By coupling of this method to advanced ideas on large-eddy simulation, we expect to achieve progress that would not otherwise be possible on these difficult flow problems. In particular, the lattice Boltzmann method for large-eddy simulation allows the efficient formulation of near-wall boundary conditions that have so far escaped analysis. It is also possible that the new formulations to be established here will suggest new computer architectures that will enable full-scale flow simulations.