Addressing the Grid-size Sensitivity Issue in Large-eddy Simulations of Stable Boundary Layers

网格各向异性、分辨率和子格尺度模型对低空云伪谱大涡模拟的影响

Effect of grid anisotropy, resolution, and subgrid-scale models in pseudo-spectral Large Eddy Simulations of low-level clouds

本文研究了网格分辨率和子格尺度模型对低空云大涡模拟的影响，采用新型框架结合伪谱对流与各向最小耗散（AMD）子格尺度模型，发现AMD模型与伪谱对流结合可在不同网格分辨率下产生稳健且准确的预测，推荐垂直间距约为水平间距三倍的网格各向异性以平衡精度和计算效率。

Residual cross-grid flow numerical error in large-eddy simulations of cumulus-topped boundary layers

A computational domain translation velocity is often used in LES simulations to improve computational performance by allowing longer time-step intervals. Even though the equations of motion are Galilean invariant, LES results have been observed to depend on the translation velocity. It is found that LES results of shallow convection depend on the domain translation velocity even when a Galilean invariant formulation is used. This type of model error is named residual cross-grid flow error, to emphasize the expectation that it should be negligible or zero. The residual gross-grid flow error is …

稳定层结大气边界层Turbulence的大涡模拟：一种尺度相关的动力学模式方法

Large-Eddy Simulation of Stably Stratified Atmospheric Boundary Layer Turbulence: A Scale-Dependent Dynamic Modeling Approach

发展了一种新的无调谐亚网格模型--局部平均尺度相关动力学（LASDD）模型，并将其应用于稳定边界层的大涡模拟（LES）。新模型动态计算Smagorinsky系数和亚网格尺度普朗特数的基础上解决的速度和温度场的局部动力学。总的来说，LES产生的湍流的统计数据与一些成熟的经验公式和理论预测（例如，Nieuwstadt的局部标度假说）是显著的。结果表明，在表层的大多数传统的亚网格尺度模式的明显改善。此外，与以前的稳定边界层的大涡模拟，有很强的依赖于网格分辨率相比，模拟统计数据与LASDD模型显示相对较小的分辨率依赖于这里考虑的网格尺寸的范围。从本质上讲，我们表明，新的LASDD模型是一个强大的亚网格尺度参数化的可靠，无调谐模拟稳定的边界层，即使相对粗糙的分辨率。

Deep learning for subgrid-scale turbulence modeling in large-eddy simulations of the atmospheric boundary layer

In large-eddy simulations, subgrid-scale (SGS) processes are parameterized as a function of filtered grid-scale variables. First-order, algebraic SGS models are based on the eddy-viscosity assumption, which does not always hold for turbulence. Here we apply supervised deep neural networks (DNNs) to learn SGS stresses from a set of neighboring coarse-grained velocity from direct numerical simulations (DNSs) of the atmospheric boundary layer at friction Reynolds numbers Re_τ up to 1243 without invoking the eddy-viscosity assumption. The DNN model was found to produce higher correlation of SGS st…

Comparison of Sub-Grid Scale Models for Large-Eddy Simulation using a High-Order Spectral Element Approximation of the Compressible Navier-Stokes Equations at Low Mach Number

This study aims to identify the properties, advantages, and drawbacks of some common (and some less common) sub-grid scale (SGS) models for large eddy simulation of low Mach compressible flows using high order spectral elements. The models investigated are the classical constant coefficient Smagorinsky-Lilly, the model by Vreman and two variants of a dynamic SGS (DSGS) model designed to stabilize finite and spectral elements for transport dominated problems. In particular, we compare one variant of DSGS that is based on a time-dependent residual version (R-DSGS) in contrast to a time-independe…

学习原生的涡分辨海洋动力学优于粗分辨率模拟与降尺度

Learning native eddy-resolving ocean dynamics outperforms coarse emulation and downscaling

该研究对比了AI模拟海洋的不同方式，发现直接在0.1°高分辨率网格学习动力学演化，比1°粗分辨率演化后降尺度的效果更好，能更忠实地表征海洋中尺度变率。