Communications on Applied Mathematics and Computation ›› 2024, Vol. 6 ›› Issue (4): 2239-2264.doi: 10.1007/s42967-023-00345-y

• ORIGINAL PAPERS • Previous Articles     Next Articles

Accuracy Analysis for Explicit-Implicit Finite Volume Schemes on Cut Cell Meshes

Sandra May1, Fabian Laakmann2   

  1. 1 Department of Information Technology, Uppsala University, Box 337, Uppsala 751 05, Sweden;
    2 Mathematical Institute, University of Oxford, Oxford OX2 6GG, UK
  • Received:2023-09-10 Revised:2023-09-10 Accepted:2023-09-14 Published:2024-12-20
  • Contact: Sandra May,E-mail:sandra.may@it.uu.se;Fabian Laakmann,E-mail:fabian.laakmann@maths.ox.ac.uk E-mail:sandra.may@it.uu.se;fabian.laakmann@maths.ox.ac.uk

Abstract: The solution of time-dependent hyperbolic conservation laws on cut cell meshes causes the small cell problem:standard schemes are not stable on the arbitrarily small cut cells if an explicit time stepping scheme is used and the time step size is chosen based on the size of the background cells. In May and Berger (J Sci Comput 71:919-943, 2017), the mixed explicit-implicit approach in general and MUSCL-Trap (monotonic upwind scheme for conservation laws and trapezoidal scheme) in particular have been introduced to solve this problem by using implicit time stepping on the cut cells. Theoretical and numerical results have indicated that this might lead to a loss in accuracy when switching between the explicit and implicit time stepping. In this contribution, we examine this in more detail and will prove in one dimension that the specific combination MUSCL-Trap of an explicit second-order and an implicit second-order scheme results in a fully second-order mixed scheme. As this result is unlikely to hold in two dimensions, we also introduce two new versions of mixed explicitimplicit schemes based on exchanging the explicit scheme. We present numerical tests in two dimensions where we compare the new versions with the original MUSCL-Trap scheme.

Key words: Cartesian cut cell method, Finite volume scheme, Embedded boundary grid, Mixed explicit-implicit, Truncation error, Error accumulation