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首页> 外文期刊>Computers & Fluids >Assessment of artificial fluid properties for high-order accurate large-eddy simulations of shock-free compressible turbulent flows with strong temperature gradients
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Assessment of artificial fluid properties for high-order accurate large-eddy simulations of shock-free compressible turbulent flows with strong temperature gradients

机译：评估具有强大温度梯度的无减震可压缩湍流流动的高阶精确大型大型大涡流模拟的人工液性能

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摘要

The capability of artificial fluid properties (AFP) to serve as a sub-grid scale (SGS) model and to provide stability in high-order accurate large-eddy simulations (LES) of shock-free compressible turbulent flows with strong temperature gradients is assessed. Predictive LES of such flows, which are directly relevant to applications such as engines, require an accurate description of turbulence, which typically makes them susceptible to issues of accuracy and numerical instabilities. In the present implementation, AFP schemes along with a high-order compact filter ensure robustness of otherwise non-dissipative high-order central difference spatial discretisation schemes. It is shown that a judicious choice of both filter and AFP parameters is required in order for AFP to be used as an accurate SGS model. Optimal parameter values for the AFP and the corresponding filter parameter are identified and validated in the framework of the current LES solver. First, an inviscid Taylor-Green vortex configuration is examined to evaluate the ideal combination of the filter parameter and the coefficients in the AFP framework. It is verified that AFP works as an alternative model for the unclosed subgrid-scale (SGS) dissipation terms. The AFP results are also compared to those from the dynamic Smagorinsky model (DSM), with good agreement. Second, the optimal parameter values of AFP obtained from the inviscid Taylor-Green vortex tests are validated on a series of test configurations with increasing complexity, that include an inviscid 1D advection problem involving a thermal contact discontinuity, an inviscid 2D Kelvin-Helmholtz instability test and 3D experimental unheated and heated spatially developing turbulent round jets. Robust and accurate predictions are shown with the LES solver employing the optimal model parameters in each of these tests. In particular, good agreement between the LES predictions and experimental measurements for both the flow and temperature statistics is achieved for the laboratory jets, demonstrating the accuracy of the LES/AFP simulations applied to practical turbulent configurations. The robustness of the solver in the presence of strong temperature gradients is also demonstrated by simulating a round jet case having very high temperature gradients similar to those occurring in reacting flows. In contrast, the LES/DSM simulation of this case is noted to be unstable, and failed to provide converged results. (C) 2019 Elsevier Ltd. All rights reserved.
机译：通过作为子网格刻度（SGS）模型的人造流体性质（AFP）的能力以及以具有强大的温度梯度的无减震可压缩湍流流动的高阶精确大涡流模拟（LES）的稳定性进行了评估。预测的这种流动的流量与发动机等应用直接相关，需要准确地描述湍流，这通常使它们易于对准确度和数值不稳定性的问题影响。在本实施方案中，AFP方案以及高阶紧凑型过滤器确保不耗散高阶中心差空间离散模式的鲁棒性。结果表明，需要使用滤波器和AFP参数的明智选择，以便使用AFP作为精确的SGS模型。在当前LES求解器的框架中识别AFP和相应滤波器参数的最佳参数值。首先，检查托盘泰勒 - 绿色涡流配置，以评估滤波器参数和AFP框架中系数的理想组合。验证了AFP作为未临扫的划分规律（SGS）耗散条款的替代模型。 AFP结果也将与动态Smagorinsky模型（DSM）的结果进行比较，符合良好的协议。其次，从Inciscid Taylor-Green Vortex测试获得的AFP的最佳参数值在一系列测试配置中验证了随着复杂性的一系列测试配置，包括涉及热接触不连续性的INCISCID 1D平流问题，一种INCISCID 2D Kelvin-Helmholtz不稳定测试和3D实验未加热和加热的空间上发育湍流圆形喷射。利用在这些测试中的每个测试中采用最佳模型参数的LES解决算器显示了鲁棒和准确的预测。特别是，对实验室喷气机实现了对流量和温度统计数据的LES预测和实验测量之间的良好一致性，展示了应用于实用湍流配置的LES / AFP模拟的准确性。还通过模拟与在反应流动中发生的非常高的温度梯度相似的圆形射流壳体存在强烈的温度梯度存在下的鲁棒性。相反，这种情况的LES / DSM仿真被认为是不稳定的，并且无法提供融合结果。 （c）2019年elestvier有限公司保留所有权利。

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