A Methodology for Simulations of Complex Turbulent Flows
A Methodology for Simulations of Complex Turbulent Flows
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DOI：
10.1115/1.1517569
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发表时间：
2002-12
影响因子：
2
通讯作者：
H. Fasel;J. Seidel;S. Wernz
中科院分区：
文献类型：
--
作者：
H. Fasel;J. Seidel;S. Wernz
提出了一种计算复杂可压缩湍流时变特性的流动模拟方法。FSM的开发是在与C. Speziale（当时在波士顿大学）。有限状态机的目标是提供适当数量的湍流模拟的未解决的规模，而直接计算的最大规模。该策略通过使用最先进的湍流模型（如针对雷诺平均Navier-Stokes（RANS）开发的）和具有“贡献函数”的模型项的缩放来实现。贡献函数取决于计算中的局部和瞬时“物理”分辨率。该物理分辨率在实际模拟期间通过将最小相关尺度的大小与计算中使用的局部网格大小进行比较来确定。贡献函数的设计使得如果计算局部解析良好，则不提供建模，以便在细网格限制中接近直接数值模拟（DNS），并在粗网格限制中提供所有尺度的建模，从而接近RANS计算。在这些分辨率限制之间，贡献函数调整未解决的尺度的必要建模，而较大的（解决）尺度计算大涡模拟（LES）。然而，FSM是明显不同于LES，因为它允许在同一模拟中的RANS，LES和DNS之间的一致过渡取决于本地流的行为和“物理”分辨率。因此，对于给定的计算，FSM应该比LES所需的网格点少得多。用有限状态机计算了低马赫数下后台阶和海崖体后平面尾流以及超音速轴对称尾流，证实了这一猜想。选择这些例子，使他们暴露，一方面，模拟（物理）复杂的流动的固有困难，另一方面，证明了潜力的有限状态机方法模拟复杂的几何形状的湍流可压缩流。
A flow simulation Methodology (FSM) is presented for computing the time-dependent behavior of complex compressible turbulent flows. The development of FSM was initiated in close collaboration with C. Speziale (then at Boston University). The objective of FSM is to provide the proper amount of turbulence modeling for the unresolved scales while directly computing the largest scales. The strategy is implemented by using state-of-the-art turbulence models (as developed for Reynolds averaged Navier-Stokes (RANS)) and scaling of the model terms with a "contribution function." The contribution function is dependent on the local and instantaneous "physical" resolution in the computation. This physical resolution is determined during the actual simulation by comparing the size of the smallest relevant scales to the local grid size used in the computation. The contribution function is designed such that it provides no modeling if the computation is locally well resolved so that it approaches direct numerical simulations (DNS) in the fine-grid limit and such that it provides modeling of all scales in the coarse-grid limit and thus approaches a RANS calculation. In between these resolution limits, the contribution function adjusts the necessary modeling for the unresolved scales while the larger (resolved) scales are computed as in large eddy simulation (LES). However, FSM is distinctly different from LES in that it allows for a consistent transition between RANS, LES, and DNS within the same simulation depending on the local flow behavior and "physical" resolution. As a consequence, FSM should require considerably fewer grid points for a given calculation than would be necessary for a LES. This conjecture is substantiated by employing FSM to calculate the flow over a backward-facing step and a plane wake behind a bluff body, both at low Mach number, and supersonic axisymmetric wakes. These examples were chosen such that they expose, on the one hand, the inherent difficulties of simulating (physically) complex flows, and, on the other hand, demonstrate the potential of the FSM approach for simulations of turbulent compressible flows for complex geometries.