用等变神经网络提升湍流模型精度,验证了结构张量描述更全面的假设。
Structure tensor Reynolds-averaged Navier-Stokes turbulence models with equivariant neural networks
- 用等变神经网络构建基于结构张量的湍流闭合模型,保持对称性约束。
- 在快速畸变理论数据上,模型精度比现有方法高一个数量级。
- 适合流体力学建模、物理信息机器学习研究者参考。
准确且泛化能力强的雷诺平均纳维-斯托克斯(RANS)湍流模型依赖于有效的闭合项,但现有闭合项普遍不可靠。Kassinos 等人(J. Fluid Mechanics, 428, pp. 213–248, 2001)假设这种不可靠性源于湍流统计状态描述不足,提出结构张量作为更丰富的描述候选。为验证该假设针对快速压力应变项,本文引入基于结构张量的等变神经网络(ENNs)闭合模型,并提出一种算法以强制张量分量间的代数收缩关系。利用快速畸变理论数据进行实验表明,此类 ENNs 能有效学习涉及高阶张量的关系。结果表明,所提出的 ENN 结构张量模型在快速压力应变相关项上的精度比现有模型高出一个数量级,有效验证了 Kassinos 等人的假设。此外,ENNs 提供了与经典张量基模型相容的物理解释,支持 RANS 及其他张量建模领域中未闭合项的端到端学习,以及模型依赖关系的快速探索。
原文摘要 · Abstract (English)
Accurate and generalizable Reynolds-averaged Navier-Stokes (RANS) models for turbulent flows rely on effective closures, but currently available closures are notoriously unreliable. Kassinos et al. (J. Fluid Mechanics, 428, pp. 213-248, 2001) hypothesized that this unreliability of RANS models was due to an insufficient description of the statistical state of the turbulence and proposed a set of structure tensors as a candidate for a sufficiently rich description. To test this hypothesis for the rapid pressure-strain term, we introduce tensor-based, symmetry aware closures in terms of the structure tensors using equivariant neural networks (ENNs), and present an algorithm for enforcing algebraic contraction relations among tensor components. Using data from rapid distortion theory, experiments show that such ENNs can effectively learn relationships involving high-order tensors. The resulting ENN structure tensor models are orders of magnitude more accurate than existing models for the rapid pressure-strain correlation, effectively validating the Kassinos et al. hypothesis for this term. Results show that ENNs provide a physically consistent alternative to classical tensor basis models, enabling end-to-end learning of unclosed terms in RANS and other tensor modeling domains, and rapid exploration of model dependencies.
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