arXiv:2411.16417physics.flu-dyncs.CV2024-11

比较三种生成模型在湍流代理中的表现,发现DCGAN效率最高、效果最好。

Comparison of Generative Learning Methods for Turbulence Surrogates

  • 用VAE、DCGAN和DDPM生成湍流数据,以替代高成本模拟。
  • DCGAN和DDPM能准确复现流动的统计与空间结构,但DCGAN速度最快。
  • 适合需要快速生成高质量湍流数据的研究者使用。

湍流数值模拟因复杂性和高计算成本而面临挑战。高分辨率方法如直接数值模拟(DNS)和大涡模拟(LES)通常不具计算可行性,尤其针对工程相关问题。机器学习中生成概率模型的发展为湍流代理提供了新路径。本文研究了三种生成模型——变分自编码器(VAE)、深度卷积生成对抗网络(DCGAN)和去噪扩散概率模型(DDPM)——在二维固定圆柱尾流(冯·卡门涡街)模拟及真实实验数据(圆柱阵列尾流)中的应用。训练数据来自模拟中的LES和实验中的粒子图像测速(PIV)。评估各模型对湍流统计特性与空间结构的捕捉能力。结果表明,DDPM与DCGAN均能有效复现所有流动分布,凸显其作为高效准确湍流代理的潜力。其中,尽管训练较难(存在模式崩溃等问题),但DCGAN具有最快的推理与训练速度,所需训练数据更少,且生成结果最贴近输入流场。相比之下,VAE虽训练与生成快,但结果不佳;而DDPM虽有效,但推理与训练速度显著更慢。

原文摘要 · Abstract (English)

Numerical simulations of turbulent flows present significant challenges in fluid dynamics due to their complexity and high computational cost. High resolution techniques such as Direct Numerical Simulation (DNS) and Large Eddy Simulation (LES) are generally not computationally affordable, particularly for technologically relevant problems. Recent advances in machine learning, specifically in generative probabilistic models, offer promising alternatives as surrogates for turbulence. This paper investigates the application of three generative models - Variational Autoencoders (VAE), Deep Convolutional Generative Adversarial Networks (DCGAN), and Denoising Diffusion Probabilistic Models (DDPM) - in simulating a von Kármán vortex street around a fixed cylinder projected into 2D, as well as a real-world experimental dataset of the wake flow of a cylinder array. Training data was obtained by means of LES in the simulated case and Particle Image Velocimetry (PIV) in the experimental case. We evaluate each model's ability to capture the statistical properties and spatial structures of the turbulent flow. Our results demonstrate that DDPM and DCGAN effectively replicate all flow distributions, highlighting their potential as efficient and accurate tools for turbulence surrogacy. We find a strong argument for DCGAN, as although they are more difficult to train (due to problems such as mode collapse), they show the fastest inference and training time, require less data to train compared to VAE and DDPM, and provide the results most closely aligned with the input stream. In contrast, VAE train quickly (and can generate samples quickly) but do not produce adequate results, and DDPM, whilst effective, are significantly slower at both, inference and training time.

湍流模拟生成模型机器学习数据代理

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