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arXiv 2103.08144physics.flu-dyn
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可压缩流的压力密封和非刚性体积惩罚

Pressure-tight and non-stiff volume penalization for compressible flows

Julius Reiss

摘要:

在结构化网格中嵌入几何体可以在流体模拟中简单处理复杂对象。嵌入几何图形的各种方法都是可用的。常用的Brinkman体积惩罚模型的多孔介质的几何形状,并近似于一个固体物体的极限消失的孔隙度。在其最简单的形式中,动量方程被增加了一个惩罚流体速度的项,在许多应用中产生了良好的结果。然而,它会导致数值刚度,特别是如果高压梯度需要平衡。在这里,我们专注于多孔介质的有效体积(通常称为孔隙率)的减少的效果。推导出一种方法,它允许减少通过对象的通量几乎为零,增加很少的数值刚度。此外,无滑移边界条件和绝热边界条件的构造也很容易。孔隙度项允许保持底层数值格式的斜对称性,从而提高了数值稳定性。此外,在非惩罚域中可以实现非常好的质量和能量守恒,为此边界平滑在其定义中引入了小的模糊性。该计划进行了测试的声学场景,近不可压缩和强可压缩流。

英文摘要:

Embedding geometries in structured grids allows a simple treatment of complex objects in fluid simulations. Various methods for embedding geometries are available. The commonly used Brinkman-volume-penalization models geometries as porous media, and approximates a solid object in the limit of vanishing porosity. In its simplest form, the momentum equations are augmented by a term penalizing the fluid velocity, yielding good results in many applications. However, it induces numerical stiffness, especially if high-pressure gradients need to be balanced. Here, we focus on the effect of the reduced effective volume (commonly called porosity) of the porous medium. An approach is derived, which allows reducing the flux through objects to practically zero with little increase of numerical stiffness. Also, non-slip boundary conditions and adiabatic boundary conditions are easily constructed. The porosity terms allow keeping the skew symmetry of the underlying numerical scheme, by which the numerical stability is improved. Furthermore, very good conservation of mass and energy in the non-penalized domain can be achieved, for which the boundary smoothing introduces a small ambiguity in its definition. The scheme is tested for acoustic scenarios, for near incompressible and strongly compressible flows.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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