论文标题
关于LES数据驱动的减少订单方法进行氢声分析的比较
On the comparison of LES data-driven reduced order approaches for hydroacoustic analysis
论文作者
论文摘要
在这项工作中,将动态模式分解(DMD)和正确的正交分解(POD)方法应用于使用大型涡流模拟(LES)与FFOWCS Williams and Hawkings(FWH)相似的大声声数据集(LES)计算。首先,通过模态分解分析给出了流场的低维描述。讨论了对DMD和POD底部截断等级的敏感性,并提供了广泛的数据集,以证明两种算法都使用所有空间和时间频率重建流场的能力,以支持准确的噪声评估。结果表明,尽管DMD能够以相同数量的使用模式捕获尾流区域中更细的相干结构,但与DMD对应物相比,使用POD的重建流场显示出较小的全局时空误差的幅度。其次,使用一半快照生成的一组单独的DMD和POD模式分别使用了两个数据驱动的还原模型,该模型基于DMD Mid Cast and Pod和interpolation(PODI)。在这方面,结果证实,流场上两种降低方法的预测特征都足够准确,并且PODI结果的相对优越性比DMD的相对优势。对于目前的设置而言,由于PODI中插值误差引起的差异相比,由于PODI插值误差引起的差异相对较低,因此目前的设置相对较低。最后,对使用减少流体动态场的FWH声信号评估的处理后处理分析表明,DMD和PODI数据驱动的降低模型均具有有效且在预测声音噪声方面非常准确。
In this work, Dynamic Mode Decomposition (DMD) and Proper Orthogonal Decomposition (POD) methodologies are applied to hydroacoustic dataset computed using Large Eddy Simulation (LES) coupled with Ffowcs Williams and Hawkings (FWH) analogy. First, a low-dimensional description of the flow fields is presented with modal decomposition analysis. Sensitivity towards the DMD and POD bases truncation rank is discussed, and extensive dataset is provided to demonstrate the ability of both algorithms to reconstruct the flow fields with all the spatial and temporal frequencies necessary to support accurate noise evaluation. Results show that while DMD is capable to capture finer coherent structures in the wake region for the same amount of employed modes, reconstructed flow fields using POD exhibit smaller magnitudes of global spatiotemporal errors compared with DMD counterparts. Second, a separate set of DMD and POD modes generated using half the snapshots is employed into two data-driven reduced models respectively, based on DMD mid cast and POD with Interpolation (PODI). In that regard, results confirm that the predictive character of both reduced approaches on the flow fields is sufficiently accurate, with a relative superiority of PODI results over DMD ones. This infers that, discrepancies induced due to interpolation errors in PODI is relatively low compared with errors induced by integration and linear regression operations in DMD, for the present setup. Finally, a post processing analysis on the evaluation of FWH acoustic signals utilizing reduced fluid dynamic fields as input demonstrates that both DMD and PODI data-driven reduced models are efficient and sufficiently accurate in predicting acoustic noises.