Shifted boundary polynomial corrections for compressible flows: high order on curved domains using linear meshes

TL;DR

This paper introduces a high order polynomial correction technique for boundary conditions in compressible flow simulations, enhancing accuracy on curved domains without curved meshes, applicable to various boundary types in 2D and 3D.

Contribution

It presents a simplified reformulation of the Shifted Boundary Method that improves boundary condition consistency and accuracy without requiring curved meshes or high order Taylor series evaluations.

Findings

Achieves convergence up to order four in 2D and 3D simulations.

Effective extension to flows with shocks.

Compatible with existing finite element and finite volume codes.

Abstract

In this work we propose a simple but effective high order polynomial correction allowing to enhance the consistency of all kind of boundary conditions for the Euler equations (Dirichlet, characteristic far-field and slip-wall), both in 2D and 3D, preserving a high order of accuracy without the need of curved meshes. The method proposed is a simplified reformulation of the Shifted Boundary Method (SBM) and relies on a correction based on the extrapolated value of the in cell polynomial to the true geometry, thus not requiring the explicit evaluation of high order Taylor series. Moreover, this strategy could be easily implemented into any already existing finite element and finite volume code. Several validation tests are presented to prove the convergence properties up to order four for 2D and 3D simulations with curved boundaries, as well as an effective extension to flows with shocks.