arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2003.12165math.NAcs.NA
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动态模态分解法构造带激波双曲问题的降阶模型

Dynamic Mode Decomposition for Construction of Reduced-Order Models of Hyperbolic Problems with Shocks

Hannah Lu, Daniel M. Tartakovsky

摘要:

双曲型守恒律方程的平移性和非线性是其降阶模型的主要问题。虽然用于ROM构造的拉格朗日框架解决了平移问题,但它仅在激波形成之前有效。一旦发生这种情况,特征线彼此交叉,并且从高保真模型空间到ROM空间的投影使移动网格失真,导致数值不稳定性。我们解决这个网格失真的问题,通过开发一个物理感知的动态模式分解(DMD)方法的基础上速端图变换。后者提供了原始非线性系统与其线性对应物之间的映射,这与Koopman算子一致。这种策略与物理感知DMD的精神是一致的,因为它保留了有关冲击动力学的信息。几个数值例子来验证所提出的物理感知DMD方法来构建准确的ROM。

英文摘要:

Construction of reduced-order models (ROMs) for hyperbolic conservation laws is notoriously challenging mainly due to the translational property and nonlinearity of the governing equations. While the Lagrangian framework for ROM construction resolves the translational issue, it is valid only before a shock forms. Once that occurs, characteristic lines cross each other and projection from a high-fidelity model space onto a ROM space distorts a moving grid, resulting in numerical instabilities. We address this grid distortion issue by developing a physics-aware dynamic mode decomposition (DMD) method based on hodograph transformation. The latter provides a map between the original nonlinear system and its linear counterpart, which coincides with the Koopman operator. This strategy is consistent with the spirit of physics-aware DMDs in that it retains information about shock dynamics. Several numerical examples are presented to validate the proposed physics-aware DMD approach to constructing accurate ROMs.

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