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arXiv 2312.03136math.NAcs.NA
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非结构化多边形网格上连续介质力学的一种几何与热力学相容有限体积格式

A geometrically and thermodynamically compatible finite volume scheme for continuum mechanics on unstructured polygonal meshes

Walter Boscheri, Raphael Loubére, Jean-Philippe Braeunig, Pierre-Henri Maire

AI总结:

提出非结构化多边形网格上的新型有限体积格式,通过嵌入两个正交守恒修正同时满足GCL与热力学第二定律,并在SHTC模型和测试中验证其结构保持性质。

摘要:

我们提出了一种在非结构化多边形网格上的新型有限体积(FV)格式,该格式可被证明同时满足热力学第二定律和几何守恒律(GCL)。控制方程由对称且双曲的热力学相容(SHTC)模型类的一个子集给出。我们的数值方法离散动量、总能量、畸变张量和热冲量矢量的守恒方程,从而在一个统一的数学形式体系中解释连续介质力学中的广泛物理现象。借助直接嵌入数值通量定义中的两个守恒修正,新格式被证明满足另外两条守恒律,即熵平衡律以及将畸变张量与密度演化联系起来的几何方程。因此,经典的质量守恒方程可以被舍弃。首先,在连续层面推导GCL,随后通过引入广义势和广义Gibbs关系的新概念使其得到满足。一旦确保了GCL的相容性,便以同样方式处理热力学相容性,从而实现局部单元熵不等式的满足。这两个修正是正交的,意味着它们可以同时共存而互不干扰。新FV格式的相容性在半离散层面成立,控制PDE的时间积分依赖Runge-Kutta格式完成。大量测试案例也证明了该格式在离散层面的结构保持性质。

英文摘要:

We present a novel Finite Volume (FV) scheme on unstructured polygonal meshes that is provably compliant with the Second Law of Thermodynamics and the Geometric Conservation Law (GCL) at the same time. The governing equations are provided by a subset of the class of symmetric and hyperbolic thermodynamically compatible (SHTC) models. Our numerical method discretizes the equations for the conservation of momentum, total energy, distortion tensor and thermal impulse vector, hence accounting in one single unified mathematical formalism for a wide range of physical phenomena in continuum mechanics. By means of two conservative corrections directly embedded in the definition of the numerical fluxes, the new schemes are proven to satisfy two extra conservation laws, namely an entropy balance law and a geometric equation that links the distortion tensor to the density evolution. As such, the classical mass conservation equation can be discarded. Firstly, the GCL is derived at the continuous level, and subsequently it is satisfied by introducing the new concepts of general potential and generalized Gibbs relation. Once compatibility of the GCL is ensured, thermodynamic compatibility is tackled in the same manner, thus achieving the satisfaction of a local cell entropy inequality. The two corrections are orthogonal, meaning that they can coexist simultaneously without interfering with each other. The compatibility of the new FV schemes holds true at the semi-discrete level, and time integration of the governing PDE is carried out relying on Runge-Kutta schemes. A large suite of test cases demonstrates the structure preserving properties of the schemes at the discrete level as well.

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