从视频数据中提取烟羽动态,用简化模型快速预测污染扩散初期行为。
Coarse graining and reduced order models for plume ejection dynamics
- 基于视频帧提取烟羽中心与边缘点,构建时间序列数据用于建模。
- 通过正弦函数拟合边缘点,捕捉柯氏-赫尔姆霍兹不稳定性主导的涡旋特征。
- 无需先验物理知识,适配多种污染物源,可快速评估泄漏等环境风险。
监测大气污染物扩散对环境影响评估日益重要。高保真计算模型常用于模拟烟羽动力学,但需精细时空分辨率以解析湍流,计算成本高昂。烟羽演化包含两个关键阶段:(i) 初期喷射阶段,由剪切驱动的柯氏-赫尔姆霍兹不稳定性引发湍流混合;(ii) 后续湍流扩散与输运,通常用高斯烟羽模型描述。本文聚焦初期烟羽生成建模,提出一种数据驱动框架,直接从视频数据中推导出简化分析模型。通过提取视频快照中的烟羽中心和边缘点时间序列,评估不同回归方法的外推性能,生成表征烟羽方向与扩展的系数序列。针对边缘点采用受柯氏-赫尔姆霍兹不稳定性启发的正弦模型,识别烟羽扩散与涡量特征。该简化模型为数据驱动、轻量化方法,能捕获初始非线性点源烟羽动态的关键特征,不依赖烟羽类型,仅需视频输入。其结果可作为高斯烟羽模型等标准模型的前驱,有望实现甲烷泄漏、化学品溢出及烟道排放等关键环境危害的快速评估。
原文摘要 · Abstract (English)
Monitoring the atmospheric dispersion of pollutants is increasingly critical for environmental impact assessments. High-fidelity computational models are often employed to simulate plume dynamics, guiding decision-making and prioritizing resource deployment. However, such models can be prohibitively expensive to simulate, as they require resolving turbulent flows at fine spatial and temporal resolutions. Moreover, there are at least two distinct dynamical regimes of interest in the plume: (i) the initial ejection of the plume where turbulent mixing is generated by the shear-driven Kelvin-Helmholtz instability, and (ii) the ensuing turbulent diffusion and advection which is often modeled by the Gaussian plume model. We address the challenge of modeling the initial plume generation. Specifically, we propose a data-driven framework that identifies a reduced-order analytical model for plume dynamics -- directly from video data. We extract a time series of plume center and edge points from video snapshots and evaluate different regressions based to their extrapolation performance to generate a time series of coefficients that characterize the plume's overall direction and spread. We regress to a sinusoidal model inspired by the Kelvin-Helmholtz instability for the edge points in order to identify the plume's dispersion and vorticity. Overall, this reduced-order modeling framework provides a data-driven and lightweight approach to capture the dominant features of the initial nonlinear point-source plume dynamics, agnostic to plume type and starting only from video. The resulting model is a pre-cursor to standard models such as the Gaussian plume model and has the potential to enable rapid assessment and evaluation of critical environmental hazards, such as methane leaks, chemical spills, and pollutant dispersal from smokestacks.
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