A spectral‐element method for modelling cavitation in transient fluid–structure interaction
A spectral‐element method for modelling cavitation in transient fluid–structure interaction
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DOI：
10.1002/nme.1054
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发表时间：
2004-08
影响因子：
2.9
通讯作者：
Michael A. Sprague;T. L. Geers
中科院分区：
文献类型：
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作者：
Michael A. Sprague;T. L. Geers
在水下冲击环境中，由于冲击波从自由表面和/或润湿结构反射，导致水中压力下降到低于其蒸汽压，从而发生空化（沸腾）。如果爆炸距离结构足够远，则可以假设结构周围的流体运动很小，这允许控制流体方程的线性化。1984年，Felippa和DeRuntz开发了空化声学有限元（CAFE）方法来模拟这种现象。虽然他们的方法很强大，但对于真实的3D模拟来说太昂贵了。在这里报告的工作中，CAFE方法的效率和灵活性通过以下方式得到了极大的提高：（i）将总场分离成平衡分量、入射分量和散射分量，（ii）用高阶勒让德多项式基函数代替双线性CAFE基函数，这产生空化声学谱元（CASE）公式，（iii）采用简单的，结构和流体有限元模型的非共形耦合方法，以及（iv）引入结构-流体时间步长子循环。场分离提供了灵活性，因为它允许传播而没有数值色散的非声学入射场。CASE的使用提供了达到给定精度水平所需的流体自由度的数量的显着减少。子循环和非共形耦合的组合使用提供了计算工作量的数量级节省。这些好处说明了与1D和3D典型的水下冲击问题。版权所有© 2004年约翰威利父子有限公司。
In an underwater‐shock environment, cavitation (boiling) occurs as a result of reflection of the shock wave from the free surface and/or wetted structure causing the pressure in the water to fall below its vapour pressure. If the explosion is sufficiently distant from the structure, the motion of the fluid surrounding the structure may be assumed small, which allows linearization of the governing fluid equations. In 1984, Felippa and DeRuntz developed the cavitating acoustic finite‐element (CAFE) method for modelling this phenomenon. While their approach is robust, it is too expensive for realistic 3D simulations. In the work reported here, the efficiency and flexibility of the CAFE approach has been substantially improved by: (i) separating the total field into equilibrium, incident, and scattered components, (ii) replacing the bilinear CAFE basis functions with high‐order Legendre‐polynomial basis functions, which produces a cavitating acoustic spectral element (CASE) formulation, (iii) employing a simple, non‐conformal coupling method for the structure and fluid finite‐element models, and (iv) introducing structure–fluid time‐step subcycling. Field separation provides flexibility, as it admits non‐acoustic incident fields that propagate without numerical dispersion. The use of CASE affords a significant reduction in the number of fluid degrees of freedom required to reach a given level of accuracy. The combined use of subcycling and non‐conformal coupling affords order‐of‐magnitude savings in computational effort. These benefits are illustrated with 1D and 3D canonical underwatershock problems. Copyright © 2004 John Wiley & Sons, Ltd.