Wavelet-based grid adaptation with consistent treatment of high-order sharp immersed geometries

TL;DR

This paper introduces a high-order wavelet-based grid adaptation method that effectively handles complex immersed geometries and moving boundaries, ensuring accurate error control in PDE solutions.

Contribution

It develops a consistent high-order interpolating wavelet transform strategy compatible with immersed boundary discretizations, maintaining accuracy near complex geometries and dynamic boundaries.

Findings

Enables effective grid adaptation in complex, moving boundary problems.

Maintains high-order accuracy near immersed geometries.

Establishes a predictable relationship between refinement threshold and error.

Abstract

Wavelet-based grid adaptation methods use multiresolution analysis for error estimation, offering a mathematically rigorous approach to adaptive grid refinement when solving Partial Differential Equations (PDEs). However, applying these methods to PDE discretizations with immersed geometries is challenging, as standard interpolating wavelet transforms lose consistency near non-grid-aligned boundary intersections. To address this, we propose a high-order interpolating wavelet transform adaptation strategy compatible with sharp immersed boundary and interface discretizations. The approach performs consistent high-order wavelet transforms on narrow intervals using a 1D polynomial extrapolation technique. To maintain high order, the technique incorporates boundary values and derivatives, which are evaluated from multivariate interpolating polynomials similar to those used in high order immersed finite difference discretizations. Consequently, the proposed approach maintains the wavelet order on any arbitrary smooth multidimensional domain, including near concave geometry sections. This approach enables grid adaptation in complex domains while robustly bounding the numerical error via a manually set refinement threshold. The algorithm's performance is validated on both static and dynamic problems, including the Navier-Stokes equations with moving boundaries and temporally adapting grid resolutions. The results demonstrate that the proposed method enables effective grid adaptation, establishing a robust, predictable relationship between a user-defined refinement threshold and the overall solution error, even for problems with complex, moving boundaries.