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Second-order invariant domain preserving approximation of the Euler equations using convex limiting (1710.00417v1)

Published 1 Oct 2017 in math.NA

Abstract: A new second-order method for approximating the compressible Euler equations is introduced. The method preserves all the known invariant domains of the Euler system: positivity of the density, positivity of the internal energy and the local minimum principle on the specific entropy. The technique combines a first-order, invariant domain preserving, Guaranteed Maximum Speed method using a Graph Viscosity (GMS-GV1) with an invariant domain violating, but entropy consistent, high-order method. Invariant domain preserving auxiliary states, naturally produced by the GMS-GV1 method, are used to define local bounds for the high-order method which is then made invariant domain preserving via a convex limiting process. Numerical tests confirm the second-order accuracy of the new GMS-GV2 method in the maximum norm, where 2 stands for second-order. The proposed convex limiting is generic and can be applied to other approximation techniques and other hyperbolic systems.

Citations (95)

Summary

Numerical Challenges and Innovations in Finite Element Approximations of Euler Equations

The paper introduces a novel second-order approximation method tailored for the compressible Euler equations, leveraging a convex limiting approach that impressively preserves the known invariant domains of these equations. As the research community grapples with the complexities inherent in hyperbolic systems, particularly concerning the Euler equations, the proposed method represents a significant stride forward, focusing not on groundbreaking shifts but essential refinements in computational techniques.

Approach and Methodology

The authors focus on an explicit in-time and second-order space-time accurate method situated within the framework of continuous finite elements. Here, the strategy deviates from traditional high-order methods by integrating a first-order, invariant domain preserving, Guaranteed Maximum Speed method (GMS-GV1) with an entropy-compliant high-order approach that does not inherently preserve the invariant domain.

Convex limiting is introduced as the mechanism to mitigate any violations of invariant domains that arise in the high-order scheme. More precisely, this approach ensures that quantities such as density, internal energy, and specific entropy remain within their respective bounds, crucial for the numerical fidelity and physical realism of simulations involving Euler equations.

Numerical Results and Assertions

Numerical tests confirm the second-order accuracy of the GMS-GV2 method within the maximum norm. This is an achievement that resonates with the difficulties historically associated with maintaining accuracy alongside invariant domain properties in Euler equation approximations. The methodology promises adaptability, positing that convex limiting processes can be extended to alternative approximation techniques and other hyperbolic systems, asserting a bold yet practical path for future exploration.

Implications and Speculation

From a theoretical perspective, the introduction of convex limiting as a generic tool may redefine approaches to hyperbolic systems, offering a robust alternative to traditional methods that may falter in preserving physical constraints. Practically, the implications of this work span the spectrum from improved accuracy in simulations of fluid dynamics to refined computational models in engineering applications. As the frontier of AI-driven simulations expands, the foundational techniques presented in this paper could serve as a cornerstone for developing more sophisticated models tasked with predictive analytics and complex problem solving.

Future Directions

While this research lays down a significant foundation, ample room exists for exploration in fields such as discontinuous Galerkin and finite volume methodologies—each potentially benefiting from the introduction of convex-based limits. The broader applicability to different equations of state and more complex fluid dynamics scenarios, including real-world turbulence models, invites an exciting journey ahead, ripe for breakthroughs as computational limits are continually pushed.

In summary, the authors have artfully balanced theoretical rigor with practical usability in their approach, keeping sight of both the limitations and potential expansiveness of their method. As researchers navigate the nuances of Euler equations in AI-driven models, this work will doubtless be a touchstone, guiding efforts towards even more accurate and realistic simulation environments.

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