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arXiv 2308.02426physics.flu-dynphysics.comp-ph
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可压缩多组分流的保正性间断谱元法

Positivity-preserving discontinuous spectral element methods for compressible multi-species flows

Will Trojak, Tarik Dzanic

AI总结:

本文提出一种用于可压缩多组分流高阶间断谱元逼近的保正性、无参数自适应熵滤波数值稳定化方法,通过基于压力场收敛特性的自适应熵界开关改善了多组分界面的计算表现,并在多种数值实验中验证了其保持高阶精度、确保密度与压力正定性及低耗散捕捉小尺度特征的能力。

摘要:

我们提出了一种新颖的保正性、无参数数值稳定化方法,用于可压缩多组分流的高阶间断谱元逼近。其底层稳定化方法是自适应熵滤波方法(Dzanic 和 Witherden, J. Comput. Phys., 468, 2022),该方法被扩展至多组分流方程的守恒形式。我们证明了在滤波器中直接施加熵约束会在物质界面附近产生较差的结果,并提出了一种基于压力场收敛特性的自适应、无参数熵界开关,这极大地改善了其在多组分流中的表现。所提方法在应用于非结构网格上计算的多组分 Euler 和 Navier--Stokes 方程的多种数值实验中得到了验证,范围涵盖激波-流体相互作用问题至三维粘性流不稳定性。我们证明,该方法即使在平滑极值处也能保持底层数值格式的高阶精度,确保在激波和接触间断附近物质密度和压力的正定性,并以最小的数值耗散准确预测小尺度流动特征。

英文摘要:

We introduce a novel positivity-preserving, parameter-free numerical stabilisation approach for high-order discontinuous spectral element approximations of compressible multi-species flows. The underlying stabilisation method is the adaptive entropy filtering approach (Dzanic and Witherden, J. Comput. Phys., 468, 2022), which is extended to the conservative formulation of the multi-species flow equations. We show that the straightforward enforcement of entropy constraints in the filter yields poor results around species interfaces and propose an adaptive, parameter-free switch for the entropy bounds based on the convergence properties of the pressure field which drastically improves its performance for multi-species flows. The proposed approach is shown in a variety of numerical experiments applied to the multi-species Euler and Navier--Stokes equations computed on unstructured grids, ranging from shock-fluid interaction problems to three-dimensional viscous flow instabilities. We demonstrate that the approach can retain the high-order accuracy of the underlying numerical scheme even at smooth extrema, ensure the positivity of the species density and pressure in the vicinity of shocks and contact discontinuities, and accurately predict small-scale flow features with minimal numerical dissipation.

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