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基于level set的Eulerian-Lagrangian耦合方法及其应用

A coupled Eulerian-Lagrangian method based on level set and its applications

  • 摘要: 提出了一种基于水平集的Eulerian-Lagrangian耦合方法,其中Lagrangian方法采用相容显式有限元拉氏方法,Eulerian方法采用基于近似Riemann解的有限体积Eulerian方法,多介质界面处理采用新的水平集和Ghost方法计算. 给出了若干数值算例,包括激波管问题以及金属和气体的运动界面及其大变形问题,并分别与精确解和相容显式有限元拉氏方法的计算结果进行了对比. 数值结果表明,该方法计算结果正确,精度较高,能够准确捕捉物质界面,适用于处理大变形问题.

     

    Abstract: In this paper a coupled Eulerian-Lagrangian method based on level set formulti-material compressible fluid flow involving large deformation ispresented. In the scheme, a Lagrangian method is used in the domain withsmall deformation while an Euler method is used in the domain with largedeformation. The interface is treated by a new level set method and theGhost Fluid method. Furthermore, an explicit compatible finite elementmethod is employed as the Lagrangian method. In this Lagrangian method, thefinite element method is used to discretize the fluid equations in terms ofthe framework of compatibility, an edge-centered artificial viscosity isused to capture shocks, and the subzonal perturbed pressure is used toresist spurious and unresolved grid motions. A vertex-centered finite volumemethod based on approximate Riemann solver is used as the Eulerian method.In this Eulerian method, an HLLC numerical flux adapted to various equationsof state are employed, a second order accuracy in space is achieved by usinga reconstruction of primitive variables based on WENO approach. An explicittwo-stage Runge-Kutta time-stepping scheme is used in discretization oftime. A new method to determine the signs of the level set function and anew technique to compute the velocities of the projection points of theGhost points on the interface are proposed. Numerical examples show theaccuracy as well as the robustness of the method.

     

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